A laboratory scale algal column reactor packed with 75 ml alginate algal beads was used to treat 30 mg/L Cu and Ni with a HRT of 30 minutes. At the end of loading 4L metal solution, over 97% of Cu and 91% of Ni were r...A laboratory scale algal column reactor packed with 75 ml alginate algal beads was used to treat 30 mg/L Cu and Ni with a HRT of 30 minutes. At the end of loading 4L metal solution, over 97% of Cu and 91% of Ni were removed from the wastewater with a final residual of 1.76 mg/L Cu and 8.8 mg/L Ni. Up flow was preferred to down flow in maintaining a constant flow rate and hence HRT. Amount of metal recovered during regeneration depended on concentration and nature of regenerant used. Dilute acid was a better regenerant than calcium in terms of metal recovered (90%) and volume needed for regeneration. The consistency in the metal removal performance by the algal column over 10 metal treatment and regeneration cycles suggested that the algal beads can treat Cu or Ni bearing wastewater over 400 times its own volume.展开更多
To investigate the impact of dietary supplementation of different omega-3 polyunsaturated fatty acids (n-3 PUFAs) resources on PUFAs enrichment in hen eggs, two supplemental materials, flaxseed and oil-extracted micro...To investigate the impact of dietary supplementation of different omega-3 polyunsaturated fatty acids (n-3 PUFAs) resources on PUFAs enrichment in hen eggs, two supplemental materials, flaxseed and oil-extracted microalgal residue of heterotrophic Schizochytrium, were added to the diet of laying hens in 3 groups. Results showed that supplementation with flaxseed and Schizochytrium residue gave rise to the increased, but different n-3 PUFAs levels in egg yolk, mainly α-linolenic acid (ALA) and docosahexaenoic acid (DHA). The ratio of n-6/n-3 PUFAs was reduced in all groups. After 14 days feeding of supplied PUFAs resources, n-3 PUFAs contents reached a plateau, and then remained constant during further supplementation in 3 experimental groups. Both the highest ALA level and DHA level were achieved in flaxseed group and microalgae group, reaching up to 353.69 (±68.15) mg/egg and 301.41 (± 26.76) mg/egg respectively. Moreover, the n-3 PUFAs enrichment efficiency was relatively low in flaxseed group when compared to other 2 groups. Laying rates of hens before entering peak production period could be improved by adding flaxseed but was not obviously affected by Schizochytrium residue. The egg weight, on the other hand, had no relationship with dietary supplementation. Thus, supplementation of flaxseed or Schizochytrium residue into standard feed offers an alternative choice for the production of n-3 PUFAs enriched eggs.展开更多
The goal of this study was to develop a self-settling microalgal consortium in raceway pond reactor (RPR). Experiments were carried out with cultures that developed without additional seeding, but naturally promoted b...The goal of this study was to develop a self-settling microalgal consortium in raceway pond reactor (RPR). Experiments were carried out with cultures that developed without additional seeding, but naturally promoted by process conditions in a raceway pond reactor. The changes in microalgal communities and total biomass under nitrogen and phosphorous limitations were studied in both batch and continuous systems. At the steady state batch had the population of 46% Euglena sp., 16% Closterium sp., 14% Chlorella sp., 14% Scenedesmus sp. and 10% Ankistrodesmus sp. with a maximum biomass of 900 mg/L. In order to get self-settling microalgal consortium, the operation was changed to continuous continuous mode with the aid of a specially designed settler for daily harvest and recycling of the biomass. Grazing fauna could be controlled by managing reduced liquid and solid retention time. At steady-state condition, an autofloculating and self-settling consortium was developed which had mainly Fragilaria sp., Scenedesmus sp., and filamentous Ulothrix sp. The maximum biomass concentration obtained was 140 mg/L. The presence of neutral lipid droplets in the consortium was identified by staining with Nile Red. Development of the lipid rich consortium could be a suitable method for producing biofuel.展开更多
Successful commercialization of microalgal bio-industry requires the design of an integrated microalgal biorefinery system that facilitates the co-production of biofuels, high-value products and industrial chemicals f...Successful commercialization of microalgal bio-industry requires the design of an integrated microalgal biorefinery system that facilitates the co-production of biofuels, high-value products and industrial chemicals from the biomass. In this study, we investigated the use of sugar hydrolysate obtained from enzymatic saccharification of microalgal biomass (Chlorella sp. and T. suecica) as fermentation feedstock to produce industrially important chemicals, in particular acetic acid and butyric acid. By using hydrolysate with low sugar content as substrate for the anaerobic fermentation (1.5 - 2.4 g/L), we were able to prevent the bacterium C. saccharoperbutylacetonicum from activating its solventogenesis pathway. As a result, the fermentation process generated a product stream that was dominated by organic acids (acetic acid and butyric acid) rather than solvents (butanol, ethanol and acetone). Acetic acid constituted up to 92 wt% of Chlorella’s fermentation products and 80 wt% of T. suecica’s fermentation products. For T. suecica, the fermentation consumed almost all of the sugar available in the hydrolysate (up to 92% of initial sugar) and produced a reasonable yield of fermentation products (0.08 g fermentation products/g sugar). The Gompertz equation was successfully used to predict the formation kinetics of acetic acid and other fermentation products across both species. The results in the study demonstrate the production of industrially important chemicals, such as acetic acid and butyric acid, from the fermentation of microalgal sugar. The process described in the study can potentially be used as a value-adding step to generate biochemicals from cell debris in an integrated microalgal biorefinery system.展开更多
The microalgal epibiontic communities of the brachyuran crabs Dorippe quadridens, Schizophrys aspera and Hyastenus hilgendorfi were studied during spring and summer of 2011. A total of 68 microalgal species of four ph...The microalgal epibiontic communities of the brachyuran crabs Dorippe quadridens, Schizophrys aspera and Hyastenus hilgendorfi were studied during spring and summer of 2011. A total of 68 microalgal species of four phyla （Chlorophyta, Bascillariophyta, Cyanophyta and Pyrrhophyta） was recorded in the epibiosis of the investigated brachyuran crabs males and females Generally, Bascillariophyta predominate in number of species over the other microalgal groups, followed by Cyanophyta and Pyrrhophyta, while Chlorophyta was represented by the lowest number of species. Highly percentage of occurrence of microalgal epibionts was observed on the dorsal part of the investigated crabs followed by chela and ventral parts.展开更多
Polar microalgae are microscopic organisms adapted to survive in cold and extreme habitats such as sea-ice,glaciers,lakes and snow.These microorganisms provide an essential basis as primary food sources in polar ecosy...Polar microalgae are microscopic organisms adapted to survive in cold and extreme habitats such as sea-ice,glaciers,lakes and snow.These microorganisms provide an essential basis as primary food sources in polar ecosystems.Despite their ecological importance,polar microalgae remain relatively unexplored compared to their tropical and temperate counterparts,largely due to the practical challenges of obtaining and maintaining material from the harsh polar environments.However,interest has recently surged due to their specific adaptations and potential for utilization in various fields.This review explores the survival strategies of polar microalgae and their commercial applications in healthcare and other fields.We also consider the processes involved in processing polar microalgae,from cultivation to extraction of bioactive compounds.Our findings highlight a growing need for research in this rapidly evolving field to unlock the potential of polar microalgae in multiple fields.展开更多
Efficient wastewater treatment accompanied by sustainable“nutrients/pollutants waste-wastewaterresources/energy nexus”management is acting as a prominent and urgent global issue since severe pollution has occurred i...Efficient wastewater treatment accompanied by sustainable“nutrients/pollutants waste-wastewaterresources/energy nexus”management is acting as a prominent and urgent global issue since severe pollution has occurred increasingly.Diverting wastes from wastewater into the value-added microalgalbiomass stream is a promising goal using biological wastewater treatment technologies.This review proposed an idea of upgrading the current microalgal wastewater treatment by using immobilized microalgal system.Firstly,a systematic analysis of microalgal immobilization technology is displayed through an in-depth discussion on why using immobilized microalgae for wastewater treatment.Subsequently,the main technical approaches employed for microalgal immobilization and pollutant removal mechanisms by immobilized microalgae are summarized.Furthermore,from high-tech technologies to promote large-scale production and application potentials in diverse wastewater and bioreactors to downstream applications lead upgradation closer,the feasibility of upgrading existing microalgal wastewater treatment into immobilized microalgal systems is thoroughly discussed.Eventually,several research directions are proposed toward the future immobilized microalgal system for microalgal wastewater treatment upgrading.Together,it appears that using immobilization for further upgrading the microalgae-based wastewater treatment can be recognized as an achievable alternative to make microalgal wastewater treatment more realistic.The information and perspectives provided in this review also offer a feasible reference for upgrading conventional microalgae-based wastewater treatment.展开更多
Vegetative oils are closely associated with our daily life. They are widely used in food, both in cooking and as nutritional supplements, as well as in cosmetics and as fuels. Contrary to animal fats, vegetative oils ...Vegetative oils are closely associated with our daily life. They are widely used in food, both in cooking and as nutritional supplements, as well as in cosmetics and as fuels. Contrary to animal fats, vegetative oils are mixtures of liquid triacylglycerols (TAGs) with a high proportion of unsaturated fatty acids (UFAs). However, in many higher plants, only their fruits and/ or seeds contain a significant amount of oils that are valuable for industrial utilization. Microalgae are single-cell photosynthetic organisms. They contain all the oil-producing machinery present in higher plants and are original oil producers on Earth. Importantly, they can be cultivated on a large scale for production of microalgal oils with rare long-chain polyunsaturated FAs (LC-PUFAs) such as omega-3 FAs and eicosapentaenoic acid (EPA), which have health ben efits. The geno mes of human and vertebrate animals do not encode enzymes for synthesizing LC-PUFAs, and thus they have to acquire these so-called "essential FAs" via diet.展开更多
Electrochemical oxygen reduced reaction(ORR)is a critical element in clean energy development.Despite efforts to enhance gas transfer to the reaction interface,the low solubility of O_(2)molecules and slow diffusion r...Electrochemical oxygen reduced reaction(ORR)is a critical element in clean energy development.Despite efforts to enhance gas transfer to the reaction interface,the low solubility of O_(2)molecules and slow diffusion rate in liquid electrolyte is still a significant challenge.Herein,we design an artificial outer membrane on microalgal cells,which consists of a carbon dots/bilirubin oxidase(CDs/BOD)ORR catalyst layer and a L-cystine/Au nanoporous O_(2)supply layer.O_(2)generated by photosynthesis from microalgal cells then can be directly transported to the CDs/BOD catalytic interfaces,overcoming the sluggish gas transfer in the electrolyte.Thus,the cathode constructed by the fabricated microalgal cells realizes an ORR current density of 655.2μA/cm^(2) with fast ORR kinetics,which is 2.68 times higher than that of a BOD cathode fed with pure O_(2).A membrane-less glucose/O_(2)biofuel cell is further developed using the hybrid artificial cells as the cathode,and the power density is 2.39 times higher than that of a BOD cathode biofuel cell in O_(2)saturated solution.This biomimetic design supplies O_(2)directly to the carbon dots/BOD catalyst layer from the microalgae membrane through a nanoporous L-cys/Au layer,providing an alternative solution for the transfer barrier of O_(2)in the electrolyte.展开更多
Stress state of microalgal cells is caused under unfavorable conditions such as disordered light regime and depleted nitrogen. The stress state can impair photosynthetic efficiency, inhibit cell growth and result in t...Stress state of microalgal cells is caused under unfavorable conditions such as disordered light regime and depleted nitrogen. The stress state can impair photosynthetic efficiency, inhibit cell growth and result in the accumulation of triacylglycerol(TAG) from protective mechanisms. Continuous light or nitrogen starvation was applied on microalgae and performed effectively on inducing TAG production. To evaluate the light regime effect on inducing TAG production, the effect of different light regimes on nitrogen-starved Isochrysis zhangjiangensis was investigated in this work. The continuous light and nitrogen starvation elevated TAG content of biomass by 73% and 193%, respectively. Furthermore, the TAG accumulation of I. zhangjiangensis cell under nitrogen starvation decreased under aggravated stress from continuous illumination. Our results demonstrated that culturing the cells with 14 L: 10 D light regime under nitrogen starvation is the optimal mode to achieve maximal accumulation of TAG. A recovery in light regime was necessary for I. zhangjiangensis cultivation.展开更多
Microalgae cultivation has gained tremendous attention in recent years due to its great potential in green biofuel production and wastewater treatment application. Membrane technology is a great solution in separating...Microalgae cultivation has gained tremendous attention in recent years due to its great potential in green biofuel production and wastewater treatment application. Membrane technology is a great solution in separating the microalgae biomass while producing high quality of permeate for recycling. The main objective of this study was to investigate the filtration performance of Ag/GO-PVDF(silver/graphene oxide-polyvinylidene fluoride) membrane in an algalmembrane photoreactor(A-MPR) by benchmarking with a commercial PVDF(com-PVDF) membrane. In this study, Chlorella vulgaris microalgae was cultivated in synthetic wastewater in an A-MPR for ammoniacal-nitrogen and phosphorus recovery and the wastewater was further filtered using Ag/GO-PVDF and com-PVDF membranes to obtain high quality water. Spectrophotometer was used to analyze the chemical oxidation demand(COD), ammoniacal nitrogen(NH3-N) and phosphate(PO43-). The concentration of proteins and carbohydrates was measured using Bradford method and phenol-sulfuric acid method, respectively. The COD of the synthetic wastewater was reduced from(180.5 ± 5.6) ppm to(82 ± 2.6) ppm due to nutrient uptake by microalgae. Then, the Ag/GO-PVDF membrane was used to further purify the microalgae cultivated wastewater, resulting in a low COD permeate of(31 ± 4.6) ppm. The high removal rate of proteins(100%) and carbohydrates(86.6%) as the major foulant in microalgae filtration, with low membrane fouling propensity of Ag/GO-PVDF membrane is advantageous for the sustainable development of the microalgae production. Hence, the integrated A-MPR system is highly recommended as a promising approach for microalgae cultivation and wastewater polishing treatment.展开更多
During a survey for marine microalgal resources, we isolated a rare marine euglenoid from the coastal waters of Qingdao, China in 2009, and established a pure culture. Electron microscopic and molecular phylogenetic ...During a survey for marine microalgal resources, we isolated a rare marine euglenoid from the coastal waters of Qingdao, China in 2009, and established a pure culture. Electron microscopic and molecular phylogenetic （18S rDNA and 16S rDNA sequences） analyses revealed a close affinity with Eutreptiella gymnastica, a bloom-forming species. Different culture conditions were monitored to understand optimal E. gymnastica growth characteristics. The optimal growth conditions in a batch culture of this isolate were 20C, 160 gmol photons/（mE.s） of white light, and a salinity of 10-31. Nutrient experiments demonstrated that growth increased dramatically with a phosphorus concentration greater than 72 gmol/L. Understanding the effect of culture conditions on E. gymnastica may help understanding the blooming mechanism of this alga in its natural environment.展开更多
The economic development of the world is highly dependent on fossil fuel supplies which are constrained not only by limited availability but also generate high levels of pollution. Looking at the limited fossil fuel a...The economic development of the world is highly dependent on fossil fuel supplies which are constrained not only by limited availability but also generate high levels of pollution. Looking at the limited fossil fuel associated with problems, concerted efforts have been started to search for alternative bio fuels like bio ethanol and biodiesel. Since the diesel is being used massively in industrial commercial, agriculture and other sectors. Therefore, the production and utilization of biodiesel from oil seeds crops has been getting renewed interest in recent years in the India to overcome the demerits of oil from oil seed crops. The production of biodiesel from micro-algae has several advantages over the above re- sources due to higher algal biomass and oil productivities and the need of non-arable land for its growth. Industrial and municipal wastewaters can be potentially utilized for cultivation of micro algal oil that can be used for the production of biodiesel to completely displace petro diesel. The micro algal biomass has been reported to yield high oil contents and have the diesel production. Accordingly, lot of R & D work has been initiated for the growth, harvesting, oil extraction and conversion to biodiesel.展开更多
Species in genus Nannochloropsis,especially N.oceanica and N.gaditana,have been evolving as the model microalgae for both application and theory studies.The position effect of genome integration,the carrying capabilit...Species in genus Nannochloropsis,especially N.oceanica and N.gaditana,have been evolving as the model microalgae for both application and theory studies.The position effect of genome integration,the carrying capability limitation of integrative vectors and the instability of non-integrative vectors have hindered Nannochloropsis genetic modification with concatenate genes and extremely long DNA fragments.The molecular tools including genetic transformation,homologous recombination,gene edition,gene stacking and episome vectors for transient gene expression and diverse reporters and selection markers have been rapidly developing in Nannochloropsis species.The construction of animal and plant artificial chromosomes with“top down”strategy has set fine examples for the construction of Nannochloropsis artificial chromosomes(NannoACs).It seems that the methods and materials to set the foundation for constructing NannoACs are at hands.In this review,we outlined the current status of transgenes in Nannochloropsis species,summarized the limitations of both integrative and non-integrative vectors,and proposed a tentative approach to construct NannoACs by doubling and stabilizing the genome first,and then truncating the natural chromosomes.NannoACs once constructed will facilitate transferring the desired traits and concatenate genes into Nannochloropsis genetic backgrounds,thus contributing towards its genetic improvement and synthetic biological studies.展开更多
Three heterotrophic microalgae identified as Scenedesmus sp. Y5, Scenedesmus sp. Y7 and Chorellasp. Y9 were isolated and screened from natural water based on biomass yield and lipid productivity. Fatty acids’ composi...Three heterotrophic microalgae identified as Scenedesmus sp. Y5, Scenedesmus sp. Y7 and Chorellasp. Y9 were isolated and screened from natural water based on biomass yield and lipid productivity. Fatty acids’ composition analysis showed that both Y5 and Y7 mainly contained C16:0, C18:1 (n - 9), C18:2 (n - 6) and C18:3 (n - 3) and Y9 mainly contained C16:0, C18:0 and C18:2 (n - 6), suggesting that these microalgae can be ideal feedstock for biodiesel. Considering the specific growth rate and lipid productivity, the culture conditions were optimized for Scenedesmus sp. Y5, Scenedesmus sp. Y7 and Chorellasp. Y9. Based on the optimization of cultural conditions, all of these three microalgae were tested in fed-batch fermentation, and their biomass productivities were 4.960 g·L-1·d-1, 5.907 g·L-1·d-1 and 4.038 g·L-1·d-1;lipid productivities reached 1.5120 g·L-1·d-1, 1.233 g·L-1·d-1 and 0.8112 g·L-1·d-1, respectively.展开更多
Microalgae with high oil productivities are most desired in biodiesel production. Chlorella lewinii SUB3545914, was isolated and assessed for its growth rates, lipid productivities and fatty acid profiles under hetero...Microalgae with high oil productivities are most desired in biodiesel production. Chlorella lewinii SUB3545914, was isolated and assessed for its growth rates, lipid productivities and fatty acid profiles under heterotrophic cultivation. The alga was isolated after enrichment in BG-11 medium (pH = 7.3) under a light intensity of approximately 17.5 μE·m-2·s-1 at 30°C ± 2°C. In addition to morphology, polymerase chain reaction (PCR) and metagenomics were used for isolate identification. The DNA was sequenced and multiple sequence alignment of the BLASTED results revealed 95% similarity to Chlorella lewinii. Maximum growth (3.15 ± 0.06 g·L-1), lipid content (44.0%) and lipid volumetric productivities (118.80 ± 3.02 mg·L-1·day-1) in glucose supplemented media were more appreciable in comparison with the glycerol counterparts. Similarly, the highest growth (2.03 ± 0.68 g·L-1), lipid content (31.47%) and lipid productivities (47.21 ± 2.08 mg·L-1·day-1) in glycerol supplemented media were more than those got under autotrophic cultivation. Chlorophyll contents did not vary remarkably in heterotrophic cultures. The major fatty acids obtained by Gas Chromatography Mass Spectrometry (GC-MS) were oleic and Octadecanoic acids for all the culture conditions. Chlorella lewinii is appropriate for accumulating lipids for biodiesel under heterotrophic cultivation on glucose because of high lipid volumetric productivities.展开更多
Enhanced phosphorus treatment and recovery has been continuously pursued due to the stringent wastewater discharge regulations and a phosphate supply shortage. Here, a new adsorption-membrane separation strategy was d...Enhanced phosphorus treatment and recovery has been continuously pursued due to the stringent wastewater discharge regulations and a phosphate supply shortage. Here, a new adsorption-membrane separation strategy was developed for rational reutilization of phosphate from sea cucumber aquaculture wastewater using a Zr-modified-bentonite filled polyvinyl chloride membrane. The as-obtained polyvinyl chloride/Zr-modified-bentonite membrane was highly permeability (940 L/(m2·h)), 1–2 times higher than those reported in other studies, and its adsorption capacity was high (20.6 mg/g) when the phosphate concentration in water was low (5 mg/L). It remained stable under various conditions, such as different pH, initial phosphate concentrations, and the presence of different ions after 24 h of adsorption in a cross-flow filtration system. The total phosphorus and phosphate removal rate reached 91.5% and 95.9%, respectively, after the membrane was used to treat sea cucumber aquaculture wastewater for 24 h and no other water quality parameters had been changed. After the purification process, the utilization of the membrane as a new source of phosphorus in the phosphorus-free f/2 medium experiments indicated the high cultivability of economic microalgae Phaeodactylum tricornutum FACHB-863 and 1.2 times more chlorophyll a was present than in f/2 medium. The biomass and lipid content of the microalgae in the two different media were similar. The innovative polyvinyl chloride/Zr-modified-bentonite membrane used for phosphorus removal and recovery is an important instrument to establish the groundwork for both the treatment of low concentration phosphate from wastewater as well as the reuse of enriched phosphorus in required fields.展开更多
Polyaluminum chloride modified clay(PAC-MC)is a safe and efficient red tide control agent that has been studied and applied worldwide.Although it is well known that the distribution of hydrolytic aluminum species in P...Polyaluminum chloride modified clay(PAC-MC)is a safe and efficient red tide control agent that has been studied and applied worldwide.Although it is well known that the distribution of hydrolytic aluminum species in PAC affects its flocculation,little is known about the influence of particulars aluminum species on the microalgae removal efficiency of PAC-MC;this lack of knowledge creates a bottleneck in the development of more efficient MCs based on aluminum salts.The ferron method was used in this study to quantitatively analyze the distributions of and variations in different hydrolytic aluminum species during the process of microalgae removal by PAC-MC.The results showed that Ala,which made up 5%–20%of the total aluminum,and Alp,which made up 15%–55%of the total aluminum,significantly affected microalgae removal,with Pearson’s correlation coefficients of 0.83 and 0.89,respectively.Most of the aluminum in the PAC-MC sank rapidly into the sediments,but the rate and velocity of settlement were affected by the dose of modified clay.The optimal dose of PAC-MC for precipitating microalgae was determined based on its aluminum profile.These results provide guidance for the precise application of PAC-MC in the control of harmful algal blooms.展开更多
Schizochytrium sp.,a marine microalga,is a potential source of edible oil due to its short growth cycle and rapid lipid accumulation,especially of docosahexaenoic acid.An approach to isolate edible microalgal oil from...Schizochytrium sp.,a marine microalga,is a potential source of edible oil due to its short growth cycle and rapid lipid accumulation,especially of docosahexaenoic acid.An approach to isolate edible microalgal oil from Schizochytrium sp.using aqueous enzymatic extraction(AEE)was developed.Parameters were optimized by single-factor experiments followed by Box-Behnken design.Proteases were effective in extracting oil.The maximum free oil recovery(49.7%±0.58%)and total oil recovery(68.1%±0.94%)were obtained under optimum conditions of liquid-to-solid ratio of 4.8:1,a 2.5%enzyme concentration of papain and an extraction time of 2.2 h.There was a significant difference(P<0.05)in polyunsaturated fatty acid composition between microalgal oil obtained by AEE and by Soxhlet extraction,with the former having superior physiochemical properties and higher concentrations of bioactive components including total phenolic compounds and total tocopherols.These findings indicate a potential application of AEE for extraction of oil from Schizochytrium sp.展开更多
The goals of national energy security and sustainable development necessitate the role of renewable energy,of which biomass energy is an essential choice for realizing the strategic energy diversification and building...The goals of national energy security and sustainable development necessitate the role of renewable energy,of which biomass energy is an essential choice for realizing the strategic energy diversification and building a lowcarbon energy system.Microbial conversion of flue-gas-derived CO_(2) for producing biodiesel and biogas has been considered a significant technology in new energy development.Microalgae carbon sequestration is a hot research direction for researchers.However,three fundamental problems relating to energy/mass transfer and conversion remain as follows:(1)contradictory relationship between high resistance of cell membrane micropores and high flux of flue-gas-derived CO_(2) limits mass transfer rate of CO_(2) molecules across cell membrane;(2)low biocatalytic activity of intracellular enzymes with high-concentration CO_(2) results in difficulties in directional carbon/hydrogen conversion;(3)competition between multiple intracellular reaction pathways and high energy barriers of target products hinder the desirable cascade energy transfer.Therefore,key scientific issues of microbial energy conversion lie in the understanding on directional carbon/hydrogen conversion and desirable cascade energy transfer.Multiple researches have established a theoretical foundation of microbial energy conversion which strengthens energy/mass transfer in microbial cells.The innovative results in previous studies have been obtained as follows:(1)Reveal mass transfer mechanism of vortex flow across cell membrane micropores.(2)Propose a strategy that directionally regulates enzyme activity.(3)Establish chain reaction pathways coupled with step changes.展开更多
文摘A laboratory scale algal column reactor packed with 75 ml alginate algal beads was used to treat 30 mg/L Cu and Ni with a HRT of 30 minutes. At the end of loading 4L metal solution, over 97% of Cu and 91% of Ni were removed from the wastewater with a final residual of 1.76 mg/L Cu and 8.8 mg/L Ni. Up flow was preferred to down flow in maintaining a constant flow rate and hence HRT. Amount of metal recovered during regeneration depended on concentration and nature of regenerant used. Dilute acid was a better regenerant than calcium in terms of metal recovered (90%) and volume needed for regeneration. The consistency in the metal removal performance by the algal column over 10 metal treatment and regeneration cycles suggested that the algal beads can treat Cu or Ni bearing wastewater over 400 times its own volume.
文摘To investigate the impact of dietary supplementation of different omega-3 polyunsaturated fatty acids (n-3 PUFAs) resources on PUFAs enrichment in hen eggs, two supplemental materials, flaxseed and oil-extracted microalgal residue of heterotrophic Schizochytrium, were added to the diet of laying hens in 3 groups. Results showed that supplementation with flaxseed and Schizochytrium residue gave rise to the increased, but different n-3 PUFAs levels in egg yolk, mainly α-linolenic acid (ALA) and docosahexaenoic acid (DHA). The ratio of n-6/n-3 PUFAs was reduced in all groups. After 14 days feeding of supplied PUFAs resources, n-3 PUFAs contents reached a plateau, and then remained constant during further supplementation in 3 experimental groups. Both the highest ALA level and DHA level were achieved in flaxseed group and microalgae group, reaching up to 353.69 (±68.15) mg/egg and 301.41 (± 26.76) mg/egg respectively. Moreover, the n-3 PUFAs enrichment efficiency was relatively low in flaxseed group when compared to other 2 groups. Laying rates of hens before entering peak production period could be improved by adding flaxseed but was not obviously affected by Schizochytrium residue. The egg weight, on the other hand, had no relationship with dietary supplementation. Thus, supplementation of flaxseed or Schizochytrium residue into standard feed offers an alternative choice for the production of n-3 PUFAs enriched eggs.
文摘The goal of this study was to develop a self-settling microalgal consortium in raceway pond reactor (RPR). Experiments were carried out with cultures that developed without additional seeding, but naturally promoted by process conditions in a raceway pond reactor. The changes in microalgal communities and total biomass under nitrogen and phosphorous limitations were studied in both batch and continuous systems. At the steady state batch had the population of 46% Euglena sp., 16% Closterium sp., 14% Chlorella sp., 14% Scenedesmus sp. and 10% Ankistrodesmus sp. with a maximum biomass of 900 mg/L. In order to get self-settling microalgal consortium, the operation was changed to continuous continuous mode with the aid of a specially designed settler for daily harvest and recycling of the biomass. Grazing fauna could be controlled by managing reduced liquid and solid retention time. At steady-state condition, an autofloculating and self-settling consortium was developed which had mainly Fragilaria sp., Scenedesmus sp., and filamentous Ulothrix sp. The maximum biomass concentration obtained was 140 mg/L. The presence of neutral lipid droplets in the consortium was identified by staining with Nile Red. Development of the lipid rich consortium could be a suitable method for producing biofuel.
文摘Successful commercialization of microalgal bio-industry requires the design of an integrated microalgal biorefinery system that facilitates the co-production of biofuels, high-value products and industrial chemicals from the biomass. In this study, we investigated the use of sugar hydrolysate obtained from enzymatic saccharification of microalgal biomass (Chlorella sp. and T. suecica) as fermentation feedstock to produce industrially important chemicals, in particular acetic acid and butyric acid. By using hydrolysate with low sugar content as substrate for the anaerobic fermentation (1.5 - 2.4 g/L), we were able to prevent the bacterium C. saccharoperbutylacetonicum from activating its solventogenesis pathway. As a result, the fermentation process generated a product stream that was dominated by organic acids (acetic acid and butyric acid) rather than solvents (butanol, ethanol and acetone). Acetic acid constituted up to 92 wt% of Chlorella’s fermentation products and 80 wt% of T. suecica’s fermentation products. For T. suecica, the fermentation consumed almost all of the sugar available in the hydrolysate (up to 92% of initial sugar) and produced a reasonable yield of fermentation products (0.08 g fermentation products/g sugar). The Gompertz equation was successfully used to predict the formation kinetics of acetic acid and other fermentation products across both species. The results in the study demonstrate the production of industrially important chemicals, such as acetic acid and butyric acid, from the fermentation of microalgal sugar. The process described in the study can potentially be used as a value-adding step to generate biochemicals from cell debris in an integrated microalgal biorefinery system.
文摘The microalgal epibiontic communities of the brachyuran crabs Dorippe quadridens, Schizophrys aspera and Hyastenus hilgendorfi were studied during spring and summer of 2011. A total of 68 microalgal species of four phyla （Chlorophyta, Bascillariophyta, Cyanophyta and Pyrrhophyta） was recorded in the epibiosis of the investigated brachyuran crabs males and females Generally, Bascillariophyta predominate in number of species over the other microalgal groups, followed by Cyanophyta and Pyrrhophyta, while Chlorophyta was represented by the lowest number of species. Highly percentage of occurrence of microalgal epibionts was observed on the dorsal part of the investigated crabs followed by chela and ventral parts.
基金supported by the Sultan Mizan Antarctic Research Foundation Smart Partnership(YPASM)Initiative“Photoprotective Potential of Mycosporine-Like Amino Acids(MAAs)and Bioactive Compounds from Antarctic Microalgae on Human Keratinocytes”(Grant number:IMU R 289/2023)。
文摘Polar microalgae are microscopic organisms adapted to survive in cold and extreme habitats such as sea-ice,glaciers,lakes and snow.These microorganisms provide an essential basis as primary food sources in polar ecosystems.Despite their ecological importance,polar microalgae remain relatively unexplored compared to their tropical and temperate counterparts,largely due to the practical challenges of obtaining and maintaining material from the harsh polar environments.However,interest has recently surged due to their specific adaptations and potential for utilization in various fields.This review explores the survival strategies of polar microalgae and their commercial applications in healthcare and other fields.We also consider the processes involved in processing polar microalgae,from cultivation to extraction of bioactive compounds.Our findings highlight a growing need for research in this rapidly evolving field to unlock the potential of polar microalgae in multiple fields.
基金supported by the National Key Research and Development Program(No.2019YFC0408503)the Project of Thousand Youth Talents.
文摘Efficient wastewater treatment accompanied by sustainable“nutrients/pollutants waste-wastewaterresources/energy nexus”management is acting as a prominent and urgent global issue since severe pollution has occurred increasingly.Diverting wastes from wastewater into the value-added microalgalbiomass stream is a promising goal using biological wastewater treatment technologies.This review proposed an idea of upgrading the current microalgal wastewater treatment by using immobilized microalgal system.Firstly,a systematic analysis of microalgal immobilization technology is displayed through an in-depth discussion on why using immobilized microalgae for wastewater treatment.Subsequently,the main technical approaches employed for microalgal immobilization and pollutant removal mechanisms by immobilized microalgae are summarized.Furthermore,from high-tech technologies to promote large-scale production and application potentials in diverse wastewater and bioreactors to downstream applications lead upgradation closer,the feasibility of upgrading existing microalgal wastewater treatment into immobilized microalgal systems is thoroughly discussed.Eventually,several research directions are proposed toward the future immobilized microalgal system for microalgal wastewater treatment upgrading.Together,it appears that using immobilization for further upgrading the microalgae-based wastewater treatment can be recognized as an achievable alternative to make microalgal wastewater treatment more realistic.The information and perspectives provided in this review also offer a feasible reference for upgrading conventional microalgae-based wastewater treatment.
文摘Vegetative oils are closely associated with our daily life. They are widely used in food, both in cooking and as nutritional supplements, as well as in cosmetics and as fuels. Contrary to animal fats, vegetative oils are mixtures of liquid triacylglycerols (TAGs) with a high proportion of unsaturated fatty acids (UFAs). However, in many higher plants, only their fruits and/ or seeds contain a significant amount of oils that are valuable for industrial utilization. Microalgae are single-cell photosynthetic organisms. They contain all the oil-producing machinery present in higher plants and are original oil producers on Earth. Importantly, they can be cultivated on a large scale for production of microalgal oils with rare long-chain polyunsaturated FAs (LC-PUFAs) such as omega-3 FAs and eicosapentaenoic acid (EPA), which have health ben efits. The geno mes of human and vertebrate animals do not encode enzymes for synthesizing LC-PUFAs, and thus they have to acquire these so-called "essential FAs" via diet.
基金the National Natural Science Foundation of China(Nos.21834004,52100014).
文摘Electrochemical oxygen reduced reaction(ORR)is a critical element in clean energy development.Despite efforts to enhance gas transfer to the reaction interface,the low solubility of O_(2)molecules and slow diffusion rate in liquid electrolyte is still a significant challenge.Herein,we design an artificial outer membrane on microalgal cells,which consists of a carbon dots/bilirubin oxidase(CDs/BOD)ORR catalyst layer and a L-cystine/Au nanoporous O_(2)supply layer.O_(2)generated by photosynthesis from microalgal cells then can be directly transported to the CDs/BOD catalytic interfaces,overcoming the sluggish gas transfer in the electrolyte.Thus,the cathode constructed by the fabricated microalgal cells realizes an ORR current density of 655.2μA/cm^(2) with fast ORR kinetics,which is 2.68 times higher than that of a BOD cathode fed with pure O_(2).A membrane-less glucose/O_(2)biofuel cell is further developed using the hybrid artificial cells as the cathode,and the power density is 2.39 times higher than that of a BOD cathode biofuel cell in O_(2)saturated solution.This biomimetic design supplies O_(2)directly to the carbon dots/BOD catalyst layer from the microalgae membrane through a nanoporous L-cys/Au layer,providing an alternative solution for the transfer barrier of O_(2)in the electrolyte.
基金supported by the National High Technology Research and Development Program ‘863’ (No. 2012 AA052101)the Hundred Talent Program of the Chinese Academy of Sciences (No. A1097)
文摘Stress state of microalgal cells is caused under unfavorable conditions such as disordered light regime and depleted nitrogen. The stress state can impair photosynthetic efficiency, inhibit cell growth and result in the accumulation of triacylglycerol(TAG) from protective mechanisms. Continuous light or nitrogen starvation was applied on microalgae and performed effectively on inducing TAG production. To evaluate the light regime effect on inducing TAG production, the effect of different light regimes on nitrogen-starved Isochrysis zhangjiangensis was investigated in this work. The continuous light and nitrogen starvation elevated TAG content of biomass by 73% and 193%, respectively. Furthermore, the TAG accumulation of I. zhangjiangensis cell under nitrogen starvation decreased under aggravated stress from continuous illumination. Our results demonstrated that culturing the cells with 14 L: 10 D light regime under nitrogen starvation is the optimal mode to achieve maximal accumulation of TAG. A recovery in light regime was necessary for I. zhangjiangensis cultivation.
基金supported by Universiti Kebangsaan Malaysia [Grant No.DIP-2016-031]CRIM(Center for Research and Instrumentation Management,UKM)for sponsoring the postgraduate study of W.C.Chong via Research University Zamalah Scheme and the technical supports in this work.
文摘Microalgae cultivation has gained tremendous attention in recent years due to its great potential in green biofuel production and wastewater treatment application. Membrane technology is a great solution in separating the microalgae biomass while producing high quality of permeate for recycling. The main objective of this study was to investigate the filtration performance of Ag/GO-PVDF(silver/graphene oxide-polyvinylidene fluoride) membrane in an algalmembrane photoreactor(A-MPR) by benchmarking with a commercial PVDF(com-PVDF) membrane. In this study, Chlorella vulgaris microalgae was cultivated in synthetic wastewater in an A-MPR for ammoniacal-nitrogen and phosphorus recovery and the wastewater was further filtered using Ag/GO-PVDF and com-PVDF membranes to obtain high quality water. Spectrophotometer was used to analyze the chemical oxidation demand(COD), ammoniacal nitrogen(NH3-N) and phosphate(PO43-). The concentration of proteins and carbohydrates was measured using Bradford method and phenol-sulfuric acid method, respectively. The COD of the synthetic wastewater was reduced from(180.5 ± 5.6) ppm to(82 ± 2.6) ppm due to nutrient uptake by microalgae. Then, the Ag/GO-PVDF membrane was used to further purify the microalgae cultivated wastewater, resulting in a low COD permeate of(31 ± 4.6) ppm. The high removal rate of proteins(100%) and carbohydrates(86.6%) as the major foulant in microalgae filtration, with low membrane fouling propensity of Ag/GO-PVDF membrane is advantageous for the sustainable development of the microalgae production. Hence, the integrated A-MPR system is highly recommended as a promising approach for microalgae cultivation and wastewater polishing treatment.
基金Supported by the National Special Research Fund for Non-Profit Sector(Agriculture) (No. 200903030)the National Key Basic Program of Science & Technology-Platforms of Aquaculture Stock Resourcesa Project from Chinese Academy of Sciences
文摘During a survey for marine microalgal resources, we isolated a rare marine euglenoid from the coastal waters of Qingdao, China in 2009, and established a pure culture. Electron microscopic and molecular phylogenetic （18S rDNA and 16S rDNA sequences） analyses revealed a close affinity with Eutreptiella gymnastica, a bloom-forming species. Different culture conditions were monitored to understand optimal E. gymnastica growth characteristics. The optimal growth conditions in a batch culture of this isolate were 20C, 160 gmol photons/（mE.s） of white light, and a salinity of 10-31. Nutrient experiments demonstrated that growth increased dramatically with a phosphorus concentration greater than 72 gmol/L. Understanding the effect of culture conditions on E. gymnastica may help understanding the blooming mechanism of this alga in its natural environment.
文摘The economic development of the world is highly dependent on fossil fuel supplies which are constrained not only by limited availability but also generate high levels of pollution. Looking at the limited fossil fuel associated with problems, concerted efforts have been started to search for alternative bio fuels like bio ethanol and biodiesel. Since the diesel is being used massively in industrial commercial, agriculture and other sectors. Therefore, the production and utilization of biodiesel from oil seeds crops has been getting renewed interest in recent years in the India to overcome the demerits of oil from oil seed crops. The production of biodiesel from micro-algae has several advantages over the above re- sources due to higher algal biomass and oil productivities and the need of non-arable land for its growth. Industrial and municipal wastewaters can be potentially utilized for cultivation of micro algal oil that can be used for the production of biodiesel to completely displace petro diesel. The micro algal biomass has been reported to yield high oil contents and have the diesel production. Accordingly, lot of R & D work has been initiated for the growth, harvesting, oil extraction and conversion to biodiesel.
基金Supported by the National Key R&D Program of China(Nos.2018YFD0901506,2018YFD0900305)the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2018 SDKJ0406-3)。
文摘Species in genus Nannochloropsis,especially N.oceanica and N.gaditana,have been evolving as the model microalgae for both application and theory studies.The position effect of genome integration,the carrying capability limitation of integrative vectors and the instability of non-integrative vectors have hindered Nannochloropsis genetic modification with concatenate genes and extremely long DNA fragments.The molecular tools including genetic transformation,homologous recombination,gene edition,gene stacking and episome vectors for transient gene expression and diverse reporters and selection markers have been rapidly developing in Nannochloropsis species.The construction of animal and plant artificial chromosomes with“top down”strategy has set fine examples for the construction of Nannochloropsis artificial chromosomes(NannoACs).It seems that the methods and materials to set the foundation for constructing NannoACs are at hands.In this review,we outlined the current status of transgenes in Nannochloropsis species,summarized the limitations of both integrative and non-integrative vectors,and proposed a tentative approach to construct NannoACs by doubling and stabilizing the genome first,and then truncating the natural chromosomes.NannoACs once constructed will facilitate transferring the desired traits and concatenate genes into Nannochloropsis genetic backgrounds,thus contributing towards its genetic improvement and synthetic biological studies.
文摘Three heterotrophic microalgae identified as Scenedesmus sp. Y5, Scenedesmus sp. Y7 and Chorellasp. Y9 were isolated and screened from natural water based on biomass yield and lipid productivity. Fatty acids’ composition analysis showed that both Y5 and Y7 mainly contained C16:0, C18:1 (n - 9), C18:2 (n - 6) and C18:3 (n - 3) and Y9 mainly contained C16:0, C18:0 and C18:2 (n - 6), suggesting that these microalgae can be ideal feedstock for biodiesel. Considering the specific growth rate and lipid productivity, the culture conditions were optimized for Scenedesmus sp. Y5, Scenedesmus sp. Y7 and Chorellasp. Y9. Based on the optimization of cultural conditions, all of these three microalgae were tested in fed-batch fermentation, and their biomass productivities were 4.960 g·L-1·d-1, 5.907 g·L-1·d-1 and 4.038 g·L-1·d-1;lipid productivities reached 1.5120 g·L-1·d-1, 1.233 g·L-1·d-1 and 0.8112 g·L-1·d-1, respectively.
文摘Microalgae with high oil productivities are most desired in biodiesel production. Chlorella lewinii SUB3545914, was isolated and assessed for its growth rates, lipid productivities and fatty acid profiles under heterotrophic cultivation. The alga was isolated after enrichment in BG-11 medium (pH = 7.3) under a light intensity of approximately 17.5 μE·m-2·s-1 at 30°C ± 2°C. In addition to morphology, polymerase chain reaction (PCR) and metagenomics were used for isolate identification. The DNA was sequenced and multiple sequence alignment of the BLASTED results revealed 95% similarity to Chlorella lewinii. Maximum growth (3.15 ± 0.06 g·L-1), lipid content (44.0%) and lipid volumetric productivities (118.80 ± 3.02 mg·L-1·day-1) in glucose supplemented media were more appreciable in comparison with the glycerol counterparts. Similarly, the highest growth (2.03 ± 0.68 g·L-1), lipid content (31.47%) and lipid productivities (47.21 ± 2.08 mg·L-1·day-1) in glycerol supplemented media were more than those got under autotrophic cultivation. Chlorophyll contents did not vary remarkably in heterotrophic cultures. The major fatty acids obtained by Gas Chromatography Mass Spectrometry (GC-MS) were oleic and Octadecanoic acids for all the culture conditions. Chlorella lewinii is appropriate for accumulating lipids for biodiesel under heterotrophic cultivation on glucose because of high lipid volumetric productivities.
基金This work was successively financed by the Jiangsu Innovation Center of Marine Bioresources(China)(No.822153216).
文摘Enhanced phosphorus treatment and recovery has been continuously pursued due to the stringent wastewater discharge regulations and a phosphate supply shortage. Here, a new adsorption-membrane separation strategy was developed for rational reutilization of phosphate from sea cucumber aquaculture wastewater using a Zr-modified-bentonite filled polyvinyl chloride membrane. The as-obtained polyvinyl chloride/Zr-modified-bentonite membrane was highly permeability (940 L/(m2·h)), 1–2 times higher than those reported in other studies, and its adsorption capacity was high (20.6 mg/g) when the phosphate concentration in water was low (5 mg/L). It remained stable under various conditions, such as different pH, initial phosphate concentrations, and the presence of different ions after 24 h of adsorption in a cross-flow filtration system. The total phosphorus and phosphate removal rate reached 91.5% and 95.9%, respectively, after the membrane was used to treat sea cucumber aquaculture wastewater for 24 h and no other water quality parameters had been changed. After the purification process, the utilization of the membrane as a new source of phosphorus in the phosphorus-free f/2 medium experiments indicated the high cultivability of economic microalgae Phaeodactylum tricornutum FACHB-863 and 1.2 times more chlorophyll a was present than in f/2 medium. The biomass and lipid content of the microalgae in the two different media were similar. The innovative polyvinyl chloride/Zr-modified-bentonite membrane used for phosphorus removal and recovery is an important instrument to establish the groundwork for both the treatment of low concentration phosphate from wastewater as well as the reuse of enriched phosphorus in required fields.
基金supported by the National Natural Science Foundation of China(No.41976145)the Taishan Scholars Climbing Program of Shandong Province of 2019+1 种基金the Science and Technology Major Project of Guangxi(No.AA17202020-4)。
文摘Polyaluminum chloride modified clay(PAC-MC)is a safe and efficient red tide control agent that has been studied and applied worldwide.Although it is well known that the distribution of hydrolytic aluminum species in PAC affects its flocculation,little is known about the influence of particulars aluminum species on the microalgae removal efficiency of PAC-MC;this lack of knowledge creates a bottleneck in the development of more efficient MCs based on aluminum salts.The ferron method was used in this study to quantitatively analyze the distributions of and variations in different hydrolytic aluminum species during the process of microalgae removal by PAC-MC.The results showed that Ala,which made up 5%–20%of the total aluminum,and Alp,which made up 15%–55%of the total aluminum,significantly affected microalgae removal,with Pearson’s correlation coefficients of 0.83 and 0.89,respectively.Most of the aluminum in the PAC-MC sank rapidly into the sediments,but the rate and velocity of settlement were affected by the dose of modified clay.The optimal dose of PAC-MC for precipitating microalgae was determined based on its aluminum profile.These results provide guidance for the precise application of PAC-MC in the control of harmful algal blooms.
基金supported by grants from the National Natural Science Foundation of China(31571825,31271979)the Natural Science Foundation of Tianjin(15JCYBJC30100)+1 种基金the Innovation Foundation of Tianjin University(2017XZC-0017)the Dean Foundation of Tianjin Academy of Agricultural Sciences(14006)。
文摘Schizochytrium sp.,a marine microalga,is a potential source of edible oil due to its short growth cycle and rapid lipid accumulation,especially of docosahexaenoic acid.An approach to isolate edible microalgal oil from Schizochytrium sp.using aqueous enzymatic extraction(AEE)was developed.Parameters were optimized by single-factor experiments followed by Box-Behnken design.Proteases were effective in extracting oil.The maximum free oil recovery(49.7%±0.58%)and total oil recovery(68.1%±0.94%)were obtained under optimum conditions of liquid-to-solid ratio of 4.8:1,a 2.5%enzyme concentration of papain and an extraction time of 2.2 h.There was a significant difference(P<0.05)in polyunsaturated fatty acid composition between microalgal oil obtained by AEE and by Soxhlet extraction,with the former having superior physiochemical properties and higher concentrations of bioactive components including total phenolic compounds and total tocopherols.These findings indicate a potential application of AEE for extraction of oil from Schizochytrium sp.
基金supported by National key research and development program-China(2016YFB0601000)National Key Research and Development Program-China(2017YFE0122800).
文摘The goals of national energy security and sustainable development necessitate the role of renewable energy,of which biomass energy is an essential choice for realizing the strategic energy diversification and building a lowcarbon energy system.Microbial conversion of flue-gas-derived CO_(2) for producing biodiesel and biogas has been considered a significant technology in new energy development.Microalgae carbon sequestration is a hot research direction for researchers.However,three fundamental problems relating to energy/mass transfer and conversion remain as follows:(1)contradictory relationship between high resistance of cell membrane micropores and high flux of flue-gas-derived CO_(2) limits mass transfer rate of CO_(2) molecules across cell membrane;(2)low biocatalytic activity of intracellular enzymes with high-concentration CO_(2) results in difficulties in directional carbon/hydrogen conversion;(3)competition between multiple intracellular reaction pathways and high energy barriers of target products hinder the desirable cascade energy transfer.Therefore,key scientific issues of microbial energy conversion lie in the understanding on directional carbon/hydrogen conversion and desirable cascade energy transfer.Multiple researches have established a theoretical foundation of microbial energy conversion which strengthens energy/mass transfer in microbial cells.The innovative results in previous studies have been obtained as follows:(1)Reveal mass transfer mechanism of vortex flow across cell membrane micropores.(2)Propose a strategy that directionally regulates enzyme activity.(3)Establish chain reaction pathways coupled with step changes.
