Despite their biodegradability and economic advantage, plant leaves used as packaging can constitute a public health problem. The aim of this study was to characterize the microbial diversity contaminating plant leave...Despite their biodegradability and economic advantage, plant leaves used as packaging can constitute a public health problem. The aim of this study was to characterize the microbial diversity contaminating plant leaves used as food packaging. In total, two hundred and forty (240) samples composed of Thaumatococcus daniellii and Musa paradisiaca leaves were collected and analyzed. Microbial diversity was assessed using specific medium and biochemical tests. The resistance profile was determined by the Müeller-Hinton agar diffusion method. The resistance (blaSHV, blaIMP, blaTEM) and biofilm formation (pslA, pelA) genes were searched by PCR method. Plant leaves were contaminated by bacterial (68.7%) and fungal (100%) strains. Extreme bacterial (7.1 log10 cfu/cm2) and fungal (3.5 log10 cfu/cm2) loads were obtained on Thaumatococcus daniellii leaves. Bacterial prevalence was 45.1% (S. aureus), 38.8% (E. coli) and 16.1 (P. aeruginosa). In order of decreasing importance, the prevalence of fungal species was 41.1% (A. flavus), 33.1% (A. fumigattus), 13.7% (A. niger) and 12.1% Candida sp. Resistance of E. coli to penicillins ranges from 31.6% to 87.3% and to cephalosporins from 13.3% to 28%. The P. aeruginosa strains were mainly resistant to aztreonam (87.6%). Those of S. aureus showed resistance to tetracycline (67.6), vancomycin (53), erythromycin (44.6) and levofloxacin (32.7). The blaSHV (14.28% to 18.60%) and blaIMP (9.52% to 16.28%) genes were detected in the bacterial strains. P. aeruginosa strains (19.05%) harbored the pslA and pelA genes. The health safety of these biodegradable plant-based packaging contributes to their valorization.展开更多
Expanded polystyrene (EPS) is a common type of microplastics (MPs) often found in coastal areas especially aquaculture areas.It is considered as an important site for microbial colonization and biofilm formation,as we...Expanded polystyrene (EPS) is a common type of microplastics (MPs) often found in coastal areas especially aquaculture areas.It is considered as an important site for microbial colonization and biofilm formation,as well as a carrier of pollutants like heavy metals.However,the dynamic changes of bacterial communities attached to EPS and their interaction with heavy metals are still poorly unknown.In this study,a one-year field exposure experiment was conducted at an aquaculture farm near Donghai Island,in Leizhou Bay,Zhanjiang,Guangdong,in South China Sea.The bacterial communities attached to EPS MPs were examined by 16S r DNA high-throughput sequencing,and the relationships between bacterial biofilms and heavy metals were explored.The results show that there were notable seasonal variations in the bacterial diversity of EPS MPs.Species biodiversity was the highest in summer and the lowest in winter.The greatest number of bacterial species and lowest level of uniformity were observed in the spring.The bacterial community structure changed with exposure time,and the most significant difference in the 12-month group (P<0.05) was found.The dominant bacterial species attached to EPS MPs were mainly Proteobackteria and Firmicutes at the phylum level,and Pseudomonas and Exiguobacterium were dominant at the genus level.Furthermore,EPS MPs acted as transport carriers for potential pathogenic bacteria.High correlations were found between bacterial species and the total concentration of heavy metals on EPS MPs,as well as their speciation fractions.Different chemical speciation of heavy metals migrated and altered over seasons within biofilms,which would further exacerbate the ecological risks.展开更多
The exopolysaccharide matrix of diazotrophic cyanobacteria was used to integrate phosphorus(P)and potassium(K)solubilizing bacteria,enhancing the survival of plant growth-promoting rhizobacteria,and ultimately the sur...The exopolysaccharide matrix of diazotrophic cyanobacteria was used to integrate phosphorus(P)and potassium(K)solubilizing bacteria,enhancing the survival of plant growth-promoting rhizobacteria,and ultimately the survival of bacteria in the rhizosphere for better plant growth.A new biofilm-based formulation comprising the diazotrophic cyanobacteria Anabaena AMP2,P-solubilizing Bacillus megaterium var.phosphaticum PB1,and K-solubilizing Rhizobium pusense KRBKKM1 was tested for efficacy in rice.The growth medium with half-strength BG-11 medium supplemented with 3%glucose showed best for biofilm formation under in vitro conditions.Analysis of the methanolic extract of the cyanobacterial-bacterial biofilm(CBB)showed the activity of antioxidants,such as 2-methoxy phenol and pentadecane,which are proven to improve plant-microbe interactions and plant growth,respectively.Treatment of rice seeds with CBB extract at 100 mL/kg or 200 mL/kg showed significant enhancement in germination rate and seedling length.Therefore,a pot culture experiment with the CBB formulations was carried out,and different growth and yield parameters were recorded.Principal component analysis showed that plant growth,yield,soil dehydrogenase activity,and soil chlorophyll content were positively correlated with rice plants amended with vermiculite-based CBB at 2 kg/hm^(2) followed by a spray with aqueous CBB formulation at 5 mL/L at 15 and 30 d after rice transplanting grown with a 25%reduced level of nitrogen/phosphorus/potassium chemical fertilizers than the recommended dose.Further,Pearson correlation analysis showed that yield was positively correlated with soil dehydrogenase(r=0.92**)and soil chlorophyll content(r=0.96**).We concluded that CBB could be used as a novel biofilm-based bio-inoculant to increase rice productivity and crop fitness as a component in integrated nutrient management and sustainable organic farming strategies with reduced chemical fertilizers.展开更多
In order to promote ＂green plant protection＂, reduce the administration dosage and residue of pesticides and control cost of environment pollution, and improve maize production, quality and agricultural ecological e...In order to promote ＂green plant protection＂, reduce the administration dosage and residue of pesticides and control cost of environment pollution, and improve maize production, quality and agricultural ecological environment safety. In this study, the control effect and benefit of bio-guide wasp virus missile（BGWVM） on Ostrinia furnacalis in Nanchong City was investigated by using insect light traps and combined method of field investigation and experimental demonstration. According to the results, applying 30-37 pairs of BGWVM per hectare exhibited an average control efficiency of 78.0%, and the control cost was 139.50-172.50 CNY/hm2, which was reduced by 142.50-168.00 CNY/hm^2 compared with conventional chemical control. Average maize yield in BGWVM demonstration plot was 817.8 kg/hm2 higher and improved by 11.0% compared with blank control plot. The output value was improved by 1 799.16 CNY/hm^2 and the revenue increased by 1 941.66-1 967.16CNY/hm2. During 2003-2014, the cumulative demonstration and popularization area of BGWVM technique in Nanchong City had reached 24 507.33 hm^2, and the cumulative yield increment reached 20.042 1 million kg. BGWVM application improved total output value by 44.092 6 million CNY and saved control cost by 3.492 3-4.117 2 million CNY, thus increasing the revenue by 47.584 9-48.209 8 million CNY. BGWVM application reduced 551.41 t of 5% dimehypo GG or 12.87 t of 90%monosultap WP. In addition, BGWVM technique is simple to use, labor-saving and safe for human, animals, environment and crops, with significant economic, ecological and social benefits and without any side effect, which has become an ideal substitute for controlling O. furnacalis and reducing chemical pesticides in organic agriculture industry, modern agriculture industry, production of green and pollution-free agricultural products and IBM prevention and control demonstration gardens.展开更多
Staphylococcus aureus(S. aureus) is a common pathogenic bacterium in animal husbandry that can cause diseases such as mastitis, skin infections, arthritis, and other ailments. The formation of biofilms threatens and e...Staphylococcus aureus(S. aureus) is a common pathogenic bacterium in animal husbandry that can cause diseases such as mastitis, skin infections, arthritis, and other ailments. The formation of biofilms threatens and exacerbates S. aureus infection by allowing the bacteria to adhere to pathological areas and livestock product surfaces, thus triggering animal health crises and safety issues with livestock products. To solve this problem, in this review, we provide a brief overview of the harm caused by S. aureus and its biofilms on livestock and animal byproducts(meat and dairy products). We also describe the ways in which S. aureus spreads in animals and the threats it poses to the livestock industry. The processes and molecular mechanisms involved in biofilm formation are then explained. Finally, we discuss strategies for the removal and eradication of S. aureus and biofilms in animal husbandry, including the use of antimicrobial peptides, plant extracts, nanoparticles, phages, and antibodies. These strategies to reduce the spread of S. aureus in animal husbandry help maintain livestock health and improve productivity to ensure the ecologically sustainable development of animal husbandry and the safety of livestock products.展开更多
The world will benefit from more effective antimicrobial agents against oral conditions arising from the actions of biofilm forming bacteria. Also, information is lacking on the oral biofilm-forming bacterial diversit...The world will benefit from more effective antimicrobial agents against oral conditions arising from the actions of biofilm forming bacteria. Also, information is lacking on the oral biofilm-forming bacterial diversity in Southwestern Nigeria. In this study, we isolate and characterize oral biofilm producing bacteria in the oral cavities of schoolchildren in Southwestern Nigeria. We also investigate the antimicrobial properties of Macrosphyra longistyla extracts against the biofilm-formers and the toxicity of potent extracts. Samples were obtained from 109 schoolchildren aged 4 - 14 years from Lagos, Oyo and Osun States. Agar well diffusion technique was used in the antimicrobial susceptibility testing. Toxicity testing was done using brine shrimps (Artemia salina). Biofilm-formers in this study are Klebsiella sp., Streptococcus sp., Staphylococcus sp., and Micrococcus sp. Ethanol leaf extracts had the highest activity against all biofilm-producing bacteria. Ethanol stem bark extract, which elicited activity against Klebsiella only, was found to be less toxic than the ethanol leaf extract. Staphylococcus showed >10 mm susceptibility to the ethanol and aqueous extracts of Macrosphyra longistyla. Streptococcus and Micrococcus were susceptible to the antimicrobial actions of the ethanolic leaf extracts. Although the ethanol extracts of the leaves had lower minimum inhibitory concentrations than the ethanol extracts of the stem bark, toxicity studies showed ethanol extracts of the stem-bark to be more toxic than the ethanol extracts of the leaves. In conclusion, ethanolic extracts of Macrosphyra longistyla show potential as sources of antimicrobials against gram-positive, oral biofilm-forming bacteria.展开更多
Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellula...Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellular matrix substance (EPS). Microcolonies within biofilm are held together by interactions and bonding of the substances present in the EPS with their separation from the water channels. Similar to insoluble EPS, bacterial microcolonies release soluble exofactors that have direct impacts on the survivability, growth and antibacterial resistivity of other microcolonies made of single- or multi-species bacteria in the same biofilm. How the exofactors of microcolonies of one-type bacteria impact on microcolonies of other-type bacteria is still unclear. We studied about the role of exofactors released from Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, which are common biofilm-forming pathogenic bacteria. Exofactors facilitate to transform the microenvironment where bacteria can acquire alternative lifestyle with a long survival period and resistivity to certain antimicrobial drugs.展开更多
To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstru...To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstructure of mortar surfaces. The results show that the evolution of biofilm on mortar surfaces in simulated seawater is closely related to the corrosion suffered by the mortar, and the process of biofilm attachment and shedding is continuous and cyclical. It is found that the specimens in the absence of biofilm attachment are more severely eroded internally by the corrosive medium in simulated seawater than those in the presence of biofilm attachment. For the specimens without biofilm attachment, after 60 days, gypsum forms,and after 120 days, the number of pores in the mortar is reduced. In contrast, for the specimens in the presence of biofilm attachment, gypsum could only be detected after 90 days, and fewer pores are filled. Therefore, the formation of biofilm could delay the invasion of the corrosive medium into the interior of mortar during the evolution of biofilm on mortar surfaces, mitigating the corrosion of mortars in seawater.展开更多
The intrinsic resistance of MRSA coupled with biofilm antibiotic tolerance challenges the antibiotic treatment of MRSA biofilm infections.Phytochemical-based nanoplatform is a promising emerging approach for treatment...The intrinsic resistance of MRSA coupled with biofilm antibiotic tolerance challenges the antibiotic treatment of MRSA biofilm infections.Phytochemical-based nanoplatform is a promising emerging approach for treatment of biofilm infection.However,their therapeutic efficacy was restricted by the low drug loading capacity and lack of selectivity.Herein,we constructed a surface charge adaptive phytochemical-based nanoparticle with high isoliquiritigenin(ISL)loading content for effective treatment of MRSA biofilm.A dimeric ISL prodrug(ISL-G2)bearing a lipase responsive ester bond was synthesized,and then encapsulated into the amphiphilic quaternized oligochitosan.The obtained ISL-G2loaded NPs possessed positively charged surface,which allowed cis-aconityl-D-tyrosine(CA-Tyr)binding via electrostatic interaction to obtain ISL-G2@TMDCOS-Tyr NPs.The NPs maintained their negatively charged surface,thus prolonging the blood circulation time.In response to low pH in the biofilms,the fast removal of CA-Tyr led to a shift in their surface charge from negative to positive,which enhanced the accumulation and penetration of NPs in the biofilms.Sequentially,the pH-triggered release of D-tyrosine dispersed the biofilm and lipase-triggered released of ISL effectively kill biofilm MRSA.An in vivo study was performed on a MRSA biofilm infected wound model.This phytochemical-based system led to~2log CFU(>99%)reduction of biofilm MRSA as compared to untreated wound(P<0.001)with negligible biotoxicity in mice.This phytochemical dimer nanoplatform shows great potential for long-term treatment of resistant bacterial infections.展开更多
Akkermansia muciniphila is one of the commensals residing within the mammalian gut and co-evolving with the host.Numerous studies have demonstrated the benefits of A.muciniphila in ameliorating metabolic disorders,whi...Akkermansia muciniphila is one of the commensals residing within the mammalian gut and co-evolving with the host.Numerous studies have demonstrated the benefits of A.muciniphila in ameliorating metabolic disorders,while little is known about the antimicrobial potential of A.muciniphila against pathogens.Here,we examined the antimicrobial and anti-virulence properties of cell free supernatant(CFS)of A.muciniphila against Salmonella Typhimurium.CFS retarded bacterial growth and inhibited the motility of S.Typhimurium SL1344 and S.Typhimurium 14028.CFS dose-dependently reduced cell hydrophobicity and auto-aggregation of both strains.Also,CFS from A.muciniphila significantly attenuated biofilm formation.Compared with untreated bacteria,CFS-treated bacteria significantly decreased adhesion and invasion to Caco-2 cells,and reduced intracellular survival in macrophages.CFS maintained antimicrobial properties after treatment with high temperatures and various proteases,while it lost its antimicrobial activity after pH neutralization.Gas chromatography-mass spectrometry(GC-MS)confirmed that A.muciniphila produced a certain amount of acetate and propionate,and ultra-high-performance liquid chromatography-mass spectrometry(UHPLCMS)identified other organic acids and metabolites in CFS.In summary,CFS from A.muciniphila exhibited anti-biofilm and anti-virulence properties against Salmonella and could be potentially utilized in the food industry for controlling Salmonella contamination and reducing infection.展开更多
Slightly acidic electrolyzed water(SAEW)has proven to be an efficient and novel sanitizer in food and agriculture field.This study assessed the efficacy of SAEW(30 mg/L)at 40℃on the inactivation of foodbome pathogens...Slightly acidic electrolyzed water(SAEW)has proven to be an efficient and novel sanitizer in food and agriculture field.This study assessed the efficacy of SAEW(30 mg/L)at 40℃on the inactivation of foodbome pathogens and detachment of multi-resistant Staphylococcus aureus(MRSA)biofilm.Furthermore.the underlying mechanism of MRS A biofilm under heated SAEW at 40℃treatment on metabolic profiles was investigated.The results showed that the heated SAEW at 40℃significantly effectively against foodbome pathogens of 1.96-7.56(lg(CFU/g))reduction in pork,chicken,spinach,and lettuce.The heated SAEW at 40℃treatment significantly reduced MRS A biofilm cells by 2.41(lg(CFU/cm^(2))).The synergistic effect of SAEW treatment showed intense anti-biofilm activity in decreasing cell density and impairing biofilm cell membranes.Global metabolic response of MRSA biofilms,treated by SAEW at 40℃,revealed the alterations of intracellular metabolites,including amino acids,organic acid,fatty acid,and lipid.Moreover,signaling pathways involved in amino acid metabolism,energy metabolism,nucleotide synthesis,carbohydrate metabolites,and lipid biosynthesis were functionally disrupted by the SAEW at 40℃treatment.As per our knowledge,this is the first research to uncover the potential mechanism of heated SAEW treatment against MRSA biofilm on food contact surface.展开更多
Microbial fuel cells have already been used as biosensors to monitor assimilable organic carbon(AOC).However,their signal production from AOC is known to be completely suppressed by dissoved oxygen(DO).In this study,t...Microbial fuel cells have already been used as biosensors to monitor assimilable organic carbon(AOC).However,their signal production from AOC is known to be completely suppressed by dissoved oxygen(DO).In this study,two identical microbial electrolysis cell(MEC)based biosensors were inoculated with marine sediment and operated at two different anodic potentials,namely-300 mV and+250 mV relative to Ag/AgCl.The MEC biosensor operated under positive anodic potential conditions had electrochemically active microbial communities on the anode,including members of the Shewanellaceae,Pseudoalteromonadaceae,and Clostridiaceae families.However,the strictly anaerobic members of the Desulfuromonadaceae,Desulfobulbaceae and Desulfobacteraceae families were found only in the negative anodic potential MEC biosensor.The positive anodic potential MEC biosensor showed several other advantages as well,such as faster start-up,significantly higher maximum current production,fivefold improvement in the AOC detection limit,and tolerance of low dissolved oxygen,compared to those obtained from the negative anodic potential MEC biosensor.The developed positive anodic potential MEC biosensor can thus be used as a real-time and inexpensive detector of AOC concentrations in high saline and low DO seawater.展开更多
Extracellular polymeric substances(EPS)constitutes crucial elements within bacterial biofilms,facili-tating accelerated antimicrobial resistance and conferring defense against the host's immune cells.Developing pr...Extracellular polymeric substances(EPS)constitutes crucial elements within bacterial biofilms,facili-tating accelerated antimicrobial resistance and conferring defense against the host's immune cells.Developing precise and effective antibiofilm approaches and strategies,tailored to the specific charac-teristics of EPS composition,can offer valuable insights for the creation of novel antimicrobial drugs.This,in turn,holds the potential to mitigate the alarming issue of bacterial drug resistance.Current analysis of EPS compositions relies heavily on colorimetric approaches with a significant bias,which is likely due to the selection of a standard compound and the cross-interference of various EPS compounds.Considering the pivotal role of EPS in biofilm functionality,it is imperative for EPS research to delve deeper into the analysis of intricate compositions,moving beyond the current focus on polymeric materials.This ne-cessitates a shift from heavy reliance on colorimetric analytic methods to more comprehensive and nuanced analytical approaches.In this study,we have provided a comprehensive summary of existing analytical methods utilized in the characterization of EPS compositions.Additionally,novel strategies aimed at targeting EPS to enhance biofilm penetration were explored,with a specific focus on high-lighting the limitations associated with colorimetric methods.Furthermore,we have outlined the challenges faced in identifying additional components of EPS and propose a prospective research plan to address these challenges.This review has the potential to guide future researchers in the search for novel compounds capable of suppressing EPS,thereby inhibiting biofilm formation.This insight opens up a new avenue for exploration within this research domain.展开更多
Pseudomonas aeruginosa is an opportunistic Gram-negative bacterium, responsible for nosocomial infections, with a complex arsenal of pathogenicity. The aim of this study was to simultaneously characterize the potentia...Pseudomonas aeruginosa is an opportunistic Gram-negative bacterium, responsible for nosocomial infections, with a complex arsenal of pathogenicity. The aim of this study was to simultaneously characterize the potential for resistance, virulence and biofilm formation in clinical strains. A total of 104 clinical P. aeruginosa strains (blood (26), stools (26), pus (26) and urine (26) were the subject of this study. The Mueller-Hinton diffusion method, agglutination test and combined disk diffusion test respectively made it possible to phenotypically determine the resistance profile, serogroups and metallo-β-lactamase production. Virulence, resistance and biofilm formation supports were detected by PCR. P. aeruginosa strains were resistant to aztreonam (76.4%), ticarcillin (62.4%), piperacillin (32.4%), imipenem (17.1%), cefepime (14%) and Ceftazidime (8.3%). The serogroups O11 (22.1%), O7 (18.3%), O16 (16.3%), and O9 (14.4%) were mainly determined in clinical strains. The total prevalence of metallo-β lactamase genes was 12.5% (blaIMP) and 11.5% (blaVIM). In descending order, the virulence genes exoS (55.8%), plcH (48.1%), LasB (47.1%), pilB (42.3%) and algD (41.3%) were detected (p pelA (28.8%) and pslA (23.1%). In conclusion, this study highlights the significant resistance, virulence, and biofilm-forming capabilities of clinical Pseudomonas aeruginosa strains. By profiling 104 strains, we found high resistance rates to multiple antibiotics, with notable serogroups and a considerable prevalence of metallo-β-lactamase genes, which pose a challenge for treatment. Additionally, key virulence genes and biofilm-associated genes were prevalent, underscoring the pathogenic potential of these strains. These findings underscore the importance of characterizing pathogenicity factors as a valuable strategy for monitoring and managing P. aeruginosa infections, especially in healthcare settings where such infections are common and difficult to treat.展开更多
Background:Azadirachta indica(A.indica),commonly known as neem,is a widely distributed medicinal plant in Asia and Africa and is well known to have a wide spectrum of biological activity.A.indica is considered a skin ...Background:Azadirachta indica(A.indica),commonly known as neem,is a widely distributed medicinal plant in Asia and Africa and is well known to have a wide spectrum of biological activity.A.indica is considered a skin food that was traditionally used in different cultures to treat a wide range of skin disorders.A.indica was reported to possess antibacterial activity against Pseudomonas aeruginosa(P.aeruginosa)which is considered the most common biofilm model organism.This study aims to investigate the ability of A.indica cultivated in Egypt to inhibit/reduce the biofilm formation by P.aeruginosa.Methods:The microtiter plate assay was used to evaluate the anti-biofilm activity of neem,cultivated in Egypt,leaves against P.aeruginosa as well as the ability to reduce the activity of P.aeruginosa.To investigate the phytocompounds responsible for their bioactivity and to explore potential interactions between their bioactive components and one of the quorum-sensing regulatory proteins of P.aeruginosa involved in biofilm formation,liquid chromatography-mass spectrometric and molecular docking studies were done.Results:Results showed that methanol extract of leaves can reduce the formation of P.aeruginosa biofilm at lower concentrations than those reported in other regions with 1.25 mg/mL as the optimum concentration.The two-way analysis of variance revealed the significance of the extract effect and its concentration on the reduction of biofilm formation(P<0.05).Liquid chromatography-mass spectrometric study revealed the presence of fourteen compounds that belong to limonoids and flavonoids.Molecular docking analysis against LasR,the quorum-sensing regulatory protein,of P.aeruginosa supported these findings.Nimbolinin,a limonoid,has achieved the highest Libdock score of 138.769.Conclusion:It was concluded that A.indica,cultivated in Egypt,leaves can target LasR as a new mechanism of action for biofilm control by A.indica and therefore could be a good source of leads for anti-biofilm medicine.展开更多
In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various resul...In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (S<sub>c</sub><sub></sub>=0.1, S<sub>c</sub></sub>=1, and S<sub>c</sub></sub>=10) and a single roughness Reynolds number (Re<sub>*</sub>=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers S<sub>c</sub></sub>≥0.1, but nearly balances the turbulent flux for S<sub>c</sub></sub>=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers.展开更多
Cell immobilization plays an important role in biocatalysis for high-value products.It is necessary to maintain the viability of immobilized cells for bioconversion using viable cells as biocatalysts.In this study,a n...Cell immobilization plays an important role in biocatalysis for high-value products.It is necessary to maintain the viability of immobilized cells for bioconversion using viable cells as biocatalysts.In this study,a novel polyester nonwoven chemostat was designed for cell immobilization to investigate biofilm formation and the dynamic balance between adsorption and desorption of cells on polyester nonwoven.The polyester nonwoven was suitable for cell immobilization,and the cell numbers on the polyester nonwoven can reach 6.5±0.38 log CFU/mL.After adding the polyester nonwoven to the chemostat,the fluctuation phenomenon of free bacterial cells occurred.The reason for this phenomenon was the balance between adsorption and desorption of bacterial cells on the polyester nonwoven.Bacterial cells could adhere to the surface of polyester nonwoven via secreting extracellular polymeric substances(EPS)to form biofilms.As the maturation of biofilms,some dead cells inside the biofilms can cause the detachment of biofilms.This process of continuous adsorption and desorption of cells can ensure that the polyester nonwoven chemostat has lasting biological activity.展开更多
文摘Despite their biodegradability and economic advantage, plant leaves used as packaging can constitute a public health problem. The aim of this study was to characterize the microbial diversity contaminating plant leaves used as food packaging. In total, two hundred and forty (240) samples composed of Thaumatococcus daniellii and Musa paradisiaca leaves were collected and analyzed. Microbial diversity was assessed using specific medium and biochemical tests. The resistance profile was determined by the Müeller-Hinton agar diffusion method. The resistance (blaSHV, blaIMP, blaTEM) and biofilm formation (pslA, pelA) genes were searched by PCR method. Plant leaves were contaminated by bacterial (68.7%) and fungal (100%) strains. Extreme bacterial (7.1 log10 cfu/cm2) and fungal (3.5 log10 cfu/cm2) loads were obtained on Thaumatococcus daniellii leaves. Bacterial prevalence was 45.1% (S. aureus), 38.8% (E. coli) and 16.1 (P. aeruginosa). In order of decreasing importance, the prevalence of fungal species was 41.1% (A. flavus), 33.1% (A. fumigattus), 13.7% (A. niger) and 12.1% Candida sp. Resistance of E. coli to penicillins ranges from 31.6% to 87.3% and to cephalosporins from 13.3% to 28%. The P. aeruginosa strains were mainly resistant to aztreonam (87.6%). Those of S. aureus showed resistance to tetracycline (67.6), vancomycin (53), erythromycin (44.6) and levofloxacin (32.7). The blaSHV (14.28% to 18.60%) and blaIMP (9.52% to 16.28%) genes were detected in the bacterial strains. P. aeruginosa strains (19.05%) harbored the pslA and pelA genes. The health safety of these biodegradable plant-based packaging contributes to their valorization.
基金Supported by the Hainan Province Science and Technology Special Fund (No.ZDYF2022SHFZ317)the Guangdong Province Key Laboratory of Applied Marine Biology (No.2023B1212060047)the Program for Scientific Research Start-up Funds of Guangdong Ocean University (No.060302332301)。
文摘Expanded polystyrene (EPS) is a common type of microplastics (MPs) often found in coastal areas especially aquaculture areas.It is considered as an important site for microbial colonization and biofilm formation,as well as a carrier of pollutants like heavy metals.However,the dynamic changes of bacterial communities attached to EPS and their interaction with heavy metals are still poorly unknown.In this study,a one-year field exposure experiment was conducted at an aquaculture farm near Donghai Island,in Leizhou Bay,Zhanjiang,Guangdong,in South China Sea.The bacterial communities attached to EPS MPs were examined by 16S r DNA high-throughput sequencing,and the relationships between bacterial biofilms and heavy metals were explored.The results show that there were notable seasonal variations in the bacterial diversity of EPS MPs.Species biodiversity was the highest in summer and the lowest in winter.The greatest number of bacterial species and lowest level of uniformity were observed in the spring.The bacterial community structure changed with exposure time,and the most significant difference in the 12-month group (P<0.05) was found.The dominant bacterial species attached to EPS MPs were mainly Proteobackteria and Firmicutes at the phylum level,and Pseudomonas and Exiguobacterium were dominant at the genus level.Furthermore,EPS MPs acted as transport carriers for potential pathogenic bacteria.High correlations were found between bacterial species and the total concentration of heavy metals on EPS MPs,as well as their speciation fractions.Different chemical speciation of heavy metals migrated and altered over seasons within biofilms,which would further exacerbate the ecological risks.
基金supported by the Researchers Supporting Project of King Saud University,Riyadh,Saudi Arabia(Grant No.RSP2025R358)Tamil Nadu Agricultural University,Coimbatore,India(Grant No.NRM-MDU-AGM-14-006).
文摘The exopolysaccharide matrix of diazotrophic cyanobacteria was used to integrate phosphorus(P)and potassium(K)solubilizing bacteria,enhancing the survival of plant growth-promoting rhizobacteria,and ultimately the survival of bacteria in the rhizosphere for better plant growth.A new biofilm-based formulation comprising the diazotrophic cyanobacteria Anabaena AMP2,P-solubilizing Bacillus megaterium var.phosphaticum PB1,and K-solubilizing Rhizobium pusense KRBKKM1 was tested for efficacy in rice.The growth medium with half-strength BG-11 medium supplemented with 3%glucose showed best for biofilm formation under in vitro conditions.Analysis of the methanolic extract of the cyanobacterial-bacterial biofilm(CBB)showed the activity of antioxidants,such as 2-methoxy phenol and pentadecane,which are proven to improve plant-microbe interactions and plant growth,respectively.Treatment of rice seeds with CBB extract at 100 mL/kg or 200 mL/kg showed significant enhancement in germination rate and seedling length.Therefore,a pot culture experiment with the CBB formulations was carried out,and different growth and yield parameters were recorded.Principal component analysis showed that plant growth,yield,soil dehydrogenase activity,and soil chlorophyll content were positively correlated with rice plants amended with vermiculite-based CBB at 2 kg/hm^(2) followed by a spray with aqueous CBB formulation at 5 mL/L at 15 and 30 d after rice transplanting grown with a 25%reduced level of nitrogen/phosphorus/potassium chemical fertilizers than the recommended dose.Further,Pearson correlation analysis showed that yield was positively correlated with soil dehydrogenase(r=0.92**)and soil chlorophyll content(r=0.96**).We concluded that CBB could be used as a novel biofilm-based bio-inoculant to increase rice productivity and crop fitness as a component in integrated nutrient management and sustainable organic farming strategies with reduced chemical fertilizers.
基金Supported by Notice on the First Batch of National Modern Agricultural Demonstration Zone by the Ministry of Agriculture(NJF[2010]No.22)Program for Research and Application of Warning and Comprehensive Control Measures of Pests and Diseases of Major Grain and Oil Crops(N1997-ZC002)~~
文摘In order to promote ＂green plant protection＂, reduce the administration dosage and residue of pesticides and control cost of environment pollution, and improve maize production, quality and agricultural ecological environment safety. In this study, the control effect and benefit of bio-guide wasp virus missile（BGWVM） on Ostrinia furnacalis in Nanchong City was investigated by using insect light traps and combined method of field investigation and experimental demonstration. According to the results, applying 30-37 pairs of BGWVM per hectare exhibited an average control efficiency of 78.0%, and the control cost was 139.50-172.50 CNY/hm2, which was reduced by 142.50-168.00 CNY/hm^2 compared with conventional chemical control. Average maize yield in BGWVM demonstration plot was 817.8 kg/hm2 higher and improved by 11.0% compared with blank control plot. The output value was improved by 1 799.16 CNY/hm^2 and the revenue increased by 1 941.66-1 967.16CNY/hm2. During 2003-2014, the cumulative demonstration and popularization area of BGWVM technique in Nanchong City had reached 24 507.33 hm^2, and the cumulative yield increment reached 20.042 1 million kg. BGWVM application improved total output value by 44.092 6 million CNY and saved control cost by 3.492 3-4.117 2 million CNY, thus increasing the revenue by 47.584 9-48.209 8 million CNY. BGWVM application reduced 551.41 t of 5% dimehypo GG or 12.87 t of 90%monosultap WP. In addition, BGWVM technique is simple to use, labor-saving and safe for human, animals, environment and crops, with significant economic, ecological and social benefits and without any side effect, which has become an ideal substitute for controlling O. furnacalis and reducing chemical pesticides in organic agriculture industry, modern agriculture industry, production of green and pollution-free agricultural products and IBM prevention and control demonstration gardens.
基金supported by the National Natural Science Foundation of China (31930106 and U22A20514, U23A20232)the National Key R&D Program of China (2022YFD1300404)+2 种基金the 2115 Talent Development Program of China Agricultural University (1041-00109019)the Pinduoduo-China Agricultural University Research Fund (PC2023A01001)the Special Fund for Henan Agriculture Research System (HARS-2213-Z1)。
文摘Staphylococcus aureus(S. aureus) is a common pathogenic bacterium in animal husbandry that can cause diseases such as mastitis, skin infections, arthritis, and other ailments. The formation of biofilms threatens and exacerbates S. aureus infection by allowing the bacteria to adhere to pathological areas and livestock product surfaces, thus triggering animal health crises and safety issues with livestock products. To solve this problem, in this review, we provide a brief overview of the harm caused by S. aureus and its biofilms on livestock and animal byproducts(meat and dairy products). We also describe the ways in which S. aureus spreads in animals and the threats it poses to the livestock industry. The processes and molecular mechanisms involved in biofilm formation are then explained. Finally, we discuss strategies for the removal and eradication of S. aureus and biofilms in animal husbandry, including the use of antimicrobial peptides, plant extracts, nanoparticles, phages, and antibodies. These strategies to reduce the spread of S. aureus in animal husbandry help maintain livestock health and improve productivity to ensure the ecologically sustainable development of animal husbandry and the safety of livestock products.
文摘The world will benefit from more effective antimicrobial agents against oral conditions arising from the actions of biofilm forming bacteria. Also, information is lacking on the oral biofilm-forming bacterial diversity in Southwestern Nigeria. In this study, we isolate and characterize oral biofilm producing bacteria in the oral cavities of schoolchildren in Southwestern Nigeria. We also investigate the antimicrobial properties of Macrosphyra longistyla extracts against the biofilm-formers and the toxicity of potent extracts. Samples were obtained from 109 schoolchildren aged 4 - 14 years from Lagos, Oyo and Osun States. Agar well diffusion technique was used in the antimicrobial susceptibility testing. Toxicity testing was done using brine shrimps (Artemia salina). Biofilm-formers in this study are Klebsiella sp., Streptococcus sp., Staphylococcus sp., and Micrococcus sp. Ethanol leaf extracts had the highest activity against all biofilm-producing bacteria. Ethanol stem bark extract, which elicited activity against Klebsiella only, was found to be less toxic than the ethanol leaf extract. Staphylococcus showed >10 mm susceptibility to the ethanol and aqueous extracts of Macrosphyra longistyla. Streptococcus and Micrococcus were susceptible to the antimicrobial actions of the ethanolic leaf extracts. Although the ethanol extracts of the leaves had lower minimum inhibitory concentrations than the ethanol extracts of the stem bark, toxicity studies showed ethanol extracts of the stem-bark to be more toxic than the ethanol extracts of the leaves. In conclusion, ethanolic extracts of Macrosphyra longistyla show potential as sources of antimicrobials against gram-positive, oral biofilm-forming bacteria.
文摘Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellular matrix substance (EPS). Microcolonies within biofilm are held together by interactions and bonding of the substances present in the EPS with their separation from the water channels. Similar to insoluble EPS, bacterial microcolonies release soluble exofactors that have direct impacts on the survivability, growth and antibacterial resistivity of other microcolonies made of single- or multi-species bacteria in the same biofilm. How the exofactors of microcolonies of one-type bacteria impact on microcolonies of other-type bacteria is still unclear. We studied about the role of exofactors released from Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, which are common biofilm-forming pathogenic bacteria. Exofactors facilitate to transform the microenvironment where bacteria can acquire alternative lifestyle with a long survival period and resistivity to certain antimicrobial drugs.
基金Funded by the National Natural Science Foundation of China (Nos. 52278269, 52278268, 52178264, 52108238)Tianjin Outstanding Young Scholars Science Fund Project (No. 22JCJQJC00020)State Key Laboratory of Green Building Materials Open Foundation (No. 2021GBM08)。
文摘To explore the role of biofilm formation on the corrosion of marine concrete structures, we investigated the attachment of biofilm on mortar surfaces in simulated seawater and the influence of biofilm on the microstructure of mortar surfaces. The results show that the evolution of biofilm on mortar surfaces in simulated seawater is closely related to the corrosion suffered by the mortar, and the process of biofilm attachment and shedding is continuous and cyclical. It is found that the specimens in the absence of biofilm attachment are more severely eroded internally by the corrosive medium in simulated seawater than those in the presence of biofilm attachment. For the specimens without biofilm attachment, after 60 days, gypsum forms,and after 120 days, the number of pores in the mortar is reduced. In contrast, for the specimens in the presence of biofilm attachment, gypsum could only be detected after 90 days, and fewer pores are filled. Therefore, the formation of biofilm could delay the invasion of the corrosive medium into the interior of mortar during the evolution of biofilm on mortar surfaces, mitigating the corrosion of mortars in seawater.
基金supported by the National Natural Science Foundation of China(No.3210190403)the Natural Science Foundation of Heilongjiang Province(No.YQ2022C016)+2 种基金the China Postdoctoral Science Foundation(2022T150104and 2020M670877)the Postdoctoral Science Foundation of Heilongjiang Province(LBH-TZ2104 and LBH-Z20039)the China Agriculture Research System of MOF and MARA(No.CARS-35)。
文摘The intrinsic resistance of MRSA coupled with biofilm antibiotic tolerance challenges the antibiotic treatment of MRSA biofilm infections.Phytochemical-based nanoplatform is a promising emerging approach for treatment of biofilm infection.However,their therapeutic efficacy was restricted by the low drug loading capacity and lack of selectivity.Herein,we constructed a surface charge adaptive phytochemical-based nanoparticle with high isoliquiritigenin(ISL)loading content for effective treatment of MRSA biofilm.A dimeric ISL prodrug(ISL-G2)bearing a lipase responsive ester bond was synthesized,and then encapsulated into the amphiphilic quaternized oligochitosan.The obtained ISL-G2loaded NPs possessed positively charged surface,which allowed cis-aconityl-D-tyrosine(CA-Tyr)binding via electrostatic interaction to obtain ISL-G2@TMDCOS-Tyr NPs.The NPs maintained their negatively charged surface,thus prolonging the blood circulation time.In response to low pH in the biofilms,the fast removal of CA-Tyr led to a shift in their surface charge from negative to positive,which enhanced the accumulation and penetration of NPs in the biofilms.Sequentially,the pH-triggered release of D-tyrosine dispersed the biofilm and lipase-triggered released of ISL effectively kill biofilm MRSA.An in vivo study was performed on a MRSA biofilm infected wound model.This phytochemical-based system led to~2log CFU(>99%)reduction of biofilm MRSA as compared to untreated wound(P<0.001)with negligible biotoxicity in mice.This phytochemical dimer nanoplatform shows great potential for long-term treatment of resistant bacterial infections.
基金funded by National Key Research and Development Program of China(2022YFD2100104)Science and Technology Research Program of the Liaoning Department of Education(J2020044)+1 种基金Shaanxi Key Research and Development project(2019SF-259)LiaoNing Revitalization Talents Program(XLYC1807220).
文摘Akkermansia muciniphila is one of the commensals residing within the mammalian gut and co-evolving with the host.Numerous studies have demonstrated the benefits of A.muciniphila in ameliorating metabolic disorders,while little is known about the antimicrobial potential of A.muciniphila against pathogens.Here,we examined the antimicrobial and anti-virulence properties of cell free supernatant(CFS)of A.muciniphila against Salmonella Typhimurium.CFS retarded bacterial growth and inhibited the motility of S.Typhimurium SL1344 and S.Typhimurium 14028.CFS dose-dependently reduced cell hydrophobicity and auto-aggregation of both strains.Also,CFS from A.muciniphila significantly attenuated biofilm formation.Compared with untreated bacteria,CFS-treated bacteria significantly decreased adhesion and invasion to Caco-2 cells,and reduced intracellular survival in macrophages.CFS maintained antimicrobial properties after treatment with high temperatures and various proteases,while it lost its antimicrobial activity after pH neutralization.Gas chromatography-mass spectrometry(GC-MS)confirmed that A.muciniphila produced a certain amount of acetate and propionate,and ultra-high-performance liquid chromatography-mass spectrometry(UHPLCMS)identified other organic acids and metabolites in CFS.In summary,CFS from A.muciniphila exhibited anti-biofilm and anti-virulence properties against Salmonella and could be potentially utilized in the food industry for controlling Salmonella contamination and reducing infection.
基金supported by Brain Korea (BK)21 Plus Project (4299990913942)funded by the Korean Government,Koreathe Collabo Project funded by the Ministry of SMEs and Startups (C1016120-01-02)the National Research Foundation of Korea (NRF) (2018007551)。
文摘Slightly acidic electrolyzed water(SAEW)has proven to be an efficient and novel sanitizer in food and agriculture field.This study assessed the efficacy of SAEW(30 mg/L)at 40℃on the inactivation of foodbome pathogens and detachment of multi-resistant Staphylococcus aureus(MRSA)biofilm.Furthermore.the underlying mechanism of MRS A biofilm under heated SAEW at 40℃treatment on metabolic profiles was investigated.The results showed that the heated SAEW at 40℃significantly effectively against foodbome pathogens of 1.96-7.56(lg(CFU/g))reduction in pork,chicken,spinach,and lettuce.The heated SAEW at 40℃treatment significantly reduced MRS A biofilm cells by 2.41(lg(CFU/cm^(2))).The synergistic effect of SAEW treatment showed intense anti-biofilm activity in decreasing cell density and impairing biofilm cell membranes.Global metabolic response of MRSA biofilms,treated by SAEW at 40℃,revealed the alterations of intracellular metabolites,including amino acids,organic acid,fatty acid,and lipid.Moreover,signaling pathways involved in amino acid metabolism,energy metabolism,nucleotide synthesis,carbohydrate metabolites,and lipid biosynthesis were functionally disrupted by the SAEW at 40℃treatment.As per our knowledge,this is the first research to uncover the potential mechanism of heated SAEW treatment against MRSA biofilm on food contact surface.
基金Zhenjiang City Key R&D Plan Modern Agriculture Project(No.SH2021017)Zhenjiang“Jinshan Talents”Project 2021Jiangsu Province“Six Talent Peak”Program(No.XCL-111)。
文摘Microbial fuel cells have already been used as biosensors to monitor assimilable organic carbon(AOC).However,their signal production from AOC is known to be completely suppressed by dissoved oxygen(DO).In this study,two identical microbial electrolysis cell(MEC)based biosensors were inoculated with marine sediment and operated at two different anodic potentials,namely-300 mV and+250 mV relative to Ag/AgCl.The MEC biosensor operated under positive anodic potential conditions had electrochemically active microbial communities on the anode,including members of the Shewanellaceae,Pseudoalteromonadaceae,and Clostridiaceae families.However,the strictly anaerobic members of the Desulfuromonadaceae,Desulfobulbaceae and Desulfobacteraceae families were found only in the negative anodic potential MEC biosensor.The positive anodic potential MEC biosensor showed several other advantages as well,such as faster start-up,significantly higher maximum current production,fivefold improvement in the AOC detection limit,and tolerance of low dissolved oxygen,compared to those obtained from the negative anodic potential MEC biosensor.The developed positive anodic potential MEC biosensor can thus be used as a real-time and inexpensive detector of AOC concentrations in high saline and low DO seawater.
基金funded by the National Natural Science Foundation of China(Grant Nos.:81803812,81803237).
文摘Extracellular polymeric substances(EPS)constitutes crucial elements within bacterial biofilms,facili-tating accelerated antimicrobial resistance and conferring defense against the host's immune cells.Developing precise and effective antibiofilm approaches and strategies,tailored to the specific charac-teristics of EPS composition,can offer valuable insights for the creation of novel antimicrobial drugs.This,in turn,holds the potential to mitigate the alarming issue of bacterial drug resistance.Current analysis of EPS compositions relies heavily on colorimetric approaches with a significant bias,which is likely due to the selection of a standard compound and the cross-interference of various EPS compounds.Considering the pivotal role of EPS in biofilm functionality,it is imperative for EPS research to delve deeper into the analysis of intricate compositions,moving beyond the current focus on polymeric materials.This ne-cessitates a shift from heavy reliance on colorimetric analytic methods to more comprehensive and nuanced analytical approaches.In this study,we have provided a comprehensive summary of existing analytical methods utilized in the characterization of EPS compositions.Additionally,novel strategies aimed at targeting EPS to enhance biofilm penetration were explored,with a specific focus on high-lighting the limitations associated with colorimetric methods.Furthermore,we have outlined the challenges faced in identifying additional components of EPS and propose a prospective research plan to address these challenges.This review has the potential to guide future researchers in the search for novel compounds capable of suppressing EPS,thereby inhibiting biofilm formation.This insight opens up a new avenue for exploration within this research domain.
文摘Pseudomonas aeruginosa is an opportunistic Gram-negative bacterium, responsible for nosocomial infections, with a complex arsenal of pathogenicity. The aim of this study was to simultaneously characterize the potential for resistance, virulence and biofilm formation in clinical strains. A total of 104 clinical P. aeruginosa strains (blood (26), stools (26), pus (26) and urine (26) were the subject of this study. The Mueller-Hinton diffusion method, agglutination test and combined disk diffusion test respectively made it possible to phenotypically determine the resistance profile, serogroups and metallo-β-lactamase production. Virulence, resistance and biofilm formation supports were detected by PCR. P. aeruginosa strains were resistant to aztreonam (76.4%), ticarcillin (62.4%), piperacillin (32.4%), imipenem (17.1%), cefepime (14%) and Ceftazidime (8.3%). The serogroups O11 (22.1%), O7 (18.3%), O16 (16.3%), and O9 (14.4%) were mainly determined in clinical strains. The total prevalence of metallo-β lactamase genes was 12.5% (blaIMP) and 11.5% (blaVIM). In descending order, the virulence genes exoS (55.8%), plcH (48.1%), LasB (47.1%), pilB (42.3%) and algD (41.3%) were detected (p pelA (28.8%) and pslA (23.1%). In conclusion, this study highlights the significant resistance, virulence, and biofilm-forming capabilities of clinical Pseudomonas aeruginosa strains. By profiling 104 strains, we found high resistance rates to multiple antibiotics, with notable serogroups and a considerable prevalence of metallo-β-lactamase genes, which pose a challenge for treatment. Additionally, key virulence genes and biofilm-associated genes were prevalent, underscoring the pathogenic potential of these strains. These findings underscore the importance of characterizing pathogenicity factors as a valuable strategy for monitoring and managing P. aeruginosa infections, especially in healthcare settings where such infections are common and difficult to treat.
文摘Background:Azadirachta indica(A.indica),commonly known as neem,is a widely distributed medicinal plant in Asia and Africa and is well known to have a wide spectrum of biological activity.A.indica is considered a skin food that was traditionally used in different cultures to treat a wide range of skin disorders.A.indica was reported to possess antibacterial activity against Pseudomonas aeruginosa(P.aeruginosa)which is considered the most common biofilm model organism.This study aims to investigate the ability of A.indica cultivated in Egypt to inhibit/reduce the biofilm formation by P.aeruginosa.Methods:The microtiter plate assay was used to evaluate the anti-biofilm activity of neem,cultivated in Egypt,leaves against P.aeruginosa as well as the ability to reduce the activity of P.aeruginosa.To investigate the phytocompounds responsible for their bioactivity and to explore potential interactions between their bioactive components and one of the quorum-sensing regulatory proteins of P.aeruginosa involved in biofilm formation,liquid chromatography-mass spectrometric and molecular docking studies were done.Results:Results showed that methanol extract of leaves can reduce the formation of P.aeruginosa biofilm at lower concentrations than those reported in other regions with 1.25 mg/mL as the optimum concentration.The two-way analysis of variance revealed the significance of the extract effect and its concentration on the reduction of biofilm formation(P<0.05).Liquid chromatography-mass spectrometric study revealed the presence of fourteen compounds that belong to limonoids and flavonoids.Molecular docking analysis against LasR,the quorum-sensing regulatory protein,of P.aeruginosa supported these findings.Nimbolinin,a limonoid,has achieved the highest Libdock score of 138.769.Conclusion:It was concluded that A.indica,cultivated in Egypt,leaves can target LasR as a new mechanism of action for biofilm control by A.indica and therefore could be a good source of leads for anti-biofilm medicine.
文摘In this article dedicated to the modeling of vertical mass transfers between the biofilm and the bulk flow, we have, in the first instance, presented the methodology used, followed by the presentation of various results obtained through analyses conducted on velocity fields, different fluxes, and overall transfer coefficients. Due to numerical constraints (resolution of relevant spatial scales), we have restricted the analysis to low Schmidt numbers (S<sub>c</sub><sub></sub>=0.1, S<sub>c</sub></sub>=1, and S<sub>c</sub></sub>=10) and a single roughness Reynolds number (Re<sub>*</sub>=150). The analysis of instantaneous concentration fields from various simulations revealed logarithmic concentration profiles above the canopy. In this zone, the concentration is relatively homogeneous for longer times. The analysis of results also showed that the contribution of molecular diffusion to the total flux depends on the Schmidt number. This contribution is negligible for Schmidt numbers S<sub>c</sub></sub>≥0.1, but nearly balances the turbulent flux for S<sub>c</sub></sub>=0.1. In the canopy, the local Sherwood number, given by the ratio of the total flux (within or above the canopy) to the molecular diffusion flux at the wall, also depends on the Schmidt number and varies significantly between the canopy and the region above. The exchange velocity, a purely hydrodynamic parameter, is independent of the Schmidt number and is on the order of 10% of in the present case. This study also reveals that nutrient absorption by organisms near the wall depends on the Schmidt number. Such absorption is facilitated by lower Schmidt numbers.
基金National Key R&D Program of China,No.2022YFA0911802,Zhi-Long Xiu,2022YFA0911804,Zhi-Long Xiu。
文摘Cell immobilization plays an important role in biocatalysis for high-value products.It is necessary to maintain the viability of immobilized cells for bioconversion using viable cells as biocatalysts.In this study,a novel polyester nonwoven chemostat was designed for cell immobilization to investigate biofilm formation and the dynamic balance between adsorption and desorption of cells on polyester nonwoven.The polyester nonwoven was suitable for cell immobilization,and the cell numbers on the polyester nonwoven can reach 6.5±0.38 log CFU/mL.After adding the polyester nonwoven to the chemostat,the fluctuation phenomenon of free bacterial cells occurred.The reason for this phenomenon was the balance between adsorption and desorption of bacterial cells on the polyester nonwoven.Bacterial cells could adhere to the surface of polyester nonwoven via secreting extracellular polymeric substances(EPS)to form biofilms.As the maturation of biofilms,some dead cells inside the biofilms can cause the detachment of biofilms.This process of continuous adsorption and desorption of cells can ensure that the polyester nonwoven chemostat has lasting biological activity.
