The feasibility of using fluorescence excitation-emission matrix(EEM) along with parallel factor analysis(PARAFAC) and nonnegative least squares(NNLS) method for the differentiation of phytoplankton taxonomic groups w...The feasibility of using fluorescence excitation-emission matrix(EEM) along with parallel factor analysis(PARAFAC) and nonnegative least squares(NNLS) method for the differentiation of phytoplankton taxonomic groups was investigated. Forty-one phytoplankton species belonging to 28 genera of five divisions were studied. First, the PARAFAC model was applied to EEMs, and 15 fluorescence components were generated. Second, 15 fluorescence components were found to have a strong discriminating capability based on Bayesian discriminant analysis(BDA). Third, all spectra of the fluorescence component compositions for the 41 phytoplankton species were spectrographically sorted into 61 reference spectra using hierarchical cluster analysis(HCA), and then, the reference spectra were used to establish a database. Finally, the phytoplankton taxonomic groups was differentiated by the reference spectra database using the NNLS method. The five phytoplankton groups were differentiated with the correct discrimination ratios(CDRs) of 100% for single-species samples at the division level. The CDRs for the mixtures were above 91% for the dominant phytoplankton species and above 73% for the subdominant phytoplankton species. Sixteen of the 85 field samples collected from the Changjiang River estuary were analyzed by both HPLC-CHEMTAX and the fluorometric technique developed. The results of both methods reveal that Bacillariophyta was the dominant algal group in these 16 samples and that the subdominant algal groups comprised Dinophyta, Chlorophyta and Cryptophyta. The differentiation results by the fluorometric technique were in good agreement with those from HPLC-CHEMTAX. The results indicate that the fluorometric technique could differentiate algal taxonomic groups accurately at the division level.展开更多
Thraustochytrids are a group of unicellular marine heterotrophic protists,and have long been known for their biotechnological potentials in producing squalene,polyunsaturated fatty acids(PUFAs)and other bioactive prod...Thraustochytrids are a group of unicellular marine heterotrophic protists,and have long been known for their biotechnological potentials in producing squalene,polyunsaturated fatty acids(PUFAs)and other bioactive products.There are less than a hundred known strains from diverse marine habitats.Therefore,the discovery of new strains from natural environments is still one of the major limitations for fully exploring this interesting group of marine protists.At present,numerous attempts have been made to study thraustochytrids,mainly focusing on isolating new strains,analyzing the diversity in specific marine habitats,and increasing the yield of bioactive substances.There is a lack of a systematic study of the culturable diversity,and cultivation strategies.This paper reviews the distribution and diversity of culturable thraustochytrids from a range of marine environments,and describes in detail the most commonly used isolation methods and the control of culture parameters.Furthermore,the perspective approaches of isolation and cultivation for the discovery of new strains are discussed.Finally,the future directions of novel marine thraustochytrid research are proposed.The ultimate goal is to promote the awareness of biotechnological potentials of culturable thraustochytrid strains in industrial and biomedical applications.展开更多
Thraustochytrids,rich in docosahexaenoic acid(DHA,C22:6u3),represent a potential source of dietary fatty acids.Yet,the effect of culture conditions on growth and fatty acid composition vary widely among different thra...Thraustochytrids,rich in docosahexaenoic acid(DHA,C22:6u3),represent a potential source of dietary fatty acids.Yet,the effect of culture conditions on growth and fatty acid composition vary widely among different thraustochytrid strains.Two different thraustochytrid strains,Schizochytrium sp.PKU#Mn4 and Thraustochytriidae sp.PKU#Mn16 were studied for their growth and DHA production characteristics under various culture conditions.Although they exhibited similar fatty acid profiles,PKU#Mn4 seemed a good candidate for industrial DHA fermentation while PKU#Mn16 displayed growth tolerance to a wide range of process conditions.Relative DHA content of 48.5%and 49.2%(relative to total fatty acids),respectively,were achieved on glycerol under their optimal flask culture conditions.Maximum DHA yield(Yp/x)of 21.0%and 18.9%and productivity of 27.6 mg/L-h and 31.9 mg/L-h were obtained,respectively,in 5-L bioreactor fermentation operated with optimal conditions and dual oxygen control strategy.A 3.4-and 2.8-fold improvement of DHA production(g/L),respectively,was achieved in this study.Overall,our study provides the potential of two thraustochytrid strains and their culture conditions for efficient production of DHA-rich oil.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.41376106,41176063)the Shandong Provincial Natural Science Foundation of China(No.ZR2013DM017)
文摘The feasibility of using fluorescence excitation-emission matrix(EEM) along with parallel factor analysis(PARAFAC) and nonnegative least squares(NNLS) method for the differentiation of phytoplankton taxonomic groups was investigated. Forty-one phytoplankton species belonging to 28 genera of five divisions were studied. First, the PARAFAC model was applied to EEMs, and 15 fluorescence components were generated. Second, 15 fluorescence components were found to have a strong discriminating capability based on Bayesian discriminant analysis(BDA). Third, all spectra of the fluorescence component compositions for the 41 phytoplankton species were spectrographically sorted into 61 reference spectra using hierarchical cluster analysis(HCA), and then, the reference spectra were used to establish a database. Finally, the phytoplankton taxonomic groups was differentiated by the reference spectra database using the NNLS method. The five phytoplankton groups were differentiated with the correct discrimination ratios(CDRs) of 100% for single-species samples at the division level. The CDRs for the mixtures were above 91% for the dominant phytoplankton species and above 73% for the subdominant phytoplankton species. Sixteen of the 85 field samples collected from the Changjiang River estuary were analyzed by both HPLC-CHEMTAX and the fluorometric technique developed. The results of both methods reveal that Bacillariophyta was the dominant algal group in these 16 samples and that the subdominant algal groups comprised Dinophyta, Chlorophyta and Cryptophyta. The differentiation results by the fluorometric technique were in good agreement with those from HPLC-CHEMTAX. The results indicate that the fluorometric technique could differentiate algal taxonomic groups accurately at the division level.
基金This work was partially supported by National Science Foundation of China[91751115(GW)and 31670044(GW)]Natural Science Foundation of Hebei Province[D2019204215(QW)].The views expressed herein are those of the authors,and do not represent the views of the funding agencies or any of its subagencies.
文摘Thraustochytrids are a group of unicellular marine heterotrophic protists,and have long been known for their biotechnological potentials in producing squalene,polyunsaturated fatty acids(PUFAs)and other bioactive products.There are less than a hundred known strains from diverse marine habitats.Therefore,the discovery of new strains from natural environments is still one of the major limitations for fully exploring this interesting group of marine protists.At present,numerous attempts have been made to study thraustochytrids,mainly focusing on isolating new strains,analyzing the diversity in specific marine habitats,and increasing the yield of bioactive substances.There is a lack of a systematic study of the culturable diversity,and cultivation strategies.This paper reviews the distribution and diversity of culturable thraustochytrids from a range of marine environments,and describes in detail the most commonly used isolation methods and the control of culture parameters.Furthermore,the perspective approaches of isolation and cultivation for the discovery of new strains are discussed.Finally,the future directions of novel marine thraustochytrid research are proposed.The ultimate goal is to promote the awareness of biotechnological potentials of culturable thraustochytrid strains in industrial and biomedical applications.
基金This work was partially supported by National Key R&D Program of China(2016YFA0601400)National Science Foundation of China(31670044,91751115,and 31602185).
文摘Thraustochytrids,rich in docosahexaenoic acid(DHA,C22:6u3),represent a potential source of dietary fatty acids.Yet,the effect of culture conditions on growth and fatty acid composition vary widely among different thraustochytrid strains.Two different thraustochytrid strains,Schizochytrium sp.PKU#Mn4 and Thraustochytriidae sp.PKU#Mn16 were studied for their growth and DHA production characteristics under various culture conditions.Although they exhibited similar fatty acid profiles,PKU#Mn4 seemed a good candidate for industrial DHA fermentation while PKU#Mn16 displayed growth tolerance to a wide range of process conditions.Relative DHA content of 48.5%and 49.2%(relative to total fatty acids),respectively,were achieved on glycerol under their optimal flask culture conditions.Maximum DHA yield(Yp/x)of 21.0%and 18.9%and productivity of 27.6 mg/L-h and 31.9 mg/L-h were obtained,respectively,in 5-L bioreactor fermentation operated with optimal conditions and dual oxygen control strategy.A 3.4-and 2.8-fold improvement of DHA production(g/L),respectively,was achieved in this study.Overall,our study provides the potential of two thraustochytrid strains and their culture conditions for efficient production of DHA-rich oil.