Gamma-aminobutyric acid(GABA),widely existing in different organisms,is rapidly accumulated in plants in response to environmental stresses.The main biosynthesis and degradation pathways of GABA constitute the GABA sh...Gamma-aminobutyric acid(GABA),widely existing in different organisms,is rapidly accumulated in plants in response to environmental stresses.The main biosynthesis and degradation pathways of GABA constitute the GABA shunt,which is tied to the tricarboxylic acid(TCA)cycle.GABA transaminase(GABA-T)and succinate semialdehyde dehydrogenase(SSADH)are two essential enzymes for the GABA degradation pathway.While there are abundant studies on GABA shunt in higher plants at the physiological and genetic levels,research on its role in microalgae remains limited.This study aimed at exploring the function of GABA-T and SSADH genes in Isochrysis zhanjiangensis,an important diet microalga,under different stresses.We cloned two GABA-T genes,IzGABA-T1 and IzGABA-T2,and one SSADH gene IzSSADH from Isochrysis zhanjiangensis and conducted heterologous expression experiments.The results showed that the overexpression of IzGABA-T1 or IzGABA-T2 enhanced the survival rates of yeast transformants under heat or NaCl stress,while the overexpression of IzSSADH improved yeast tolerance to NaCl stress but had no obvious effect on heat stress.Additionally,the results of quantitative real-time polymerase chain reaction(qPCR)showed that IzGABA-T1 transcription increased in the HT(salinity 25,35℃)and LS(salinity 15,25℃)groups.At 24 h,the IzGABA-T2 transcriptions increased in the HT,LS,and HS(salinity 35,25℃)groups,but their transcription levels decreased in all groups at 48 h.IzSSADH transcription increased in the LS group.These results suggest that IzGABA-T1,IzGABA-T2,and IzSSADH are associated with temperature and salinity stresses and possess a certain preference for different stresses.展开更多
The cDNA of the delta-12 fatty acid desaturase gene, IgFAD2, was cloned from the marine microalgae Isochrysis galbana, a species capable of producing docosahexaenoic acid. Sequence analysis indicated that the open rea...The cDNA of the delta-12 fatty acid desaturase gene, IgFAD2, was cloned from the marine microalgae Isochrysis galbana, a species capable of producing docosahexaenoic acid. Sequence analysis indicated that the open reading frame measured a length of 1 158 bp and encoded 386 amino acids with a predicted molecular weight of 42.8 kDa and an isoelectric point of 9.2. Computational analysis of the protein sequence of IgFAD2 showed typical features of membrane-bound desaturase such as three conserved histidine boxes along with four membranespanning regions that were universally present among plant desaturases. Quantitative real-time PCR results showed that the abundance of IgFAD2 transcript was significantly upregulated under different environmental stresses including low temperature(15℃), high salinity(salinity of 62 and 93), and nitrogen starvation(220 μmol/L). Heterologous expression indicated that yeast cells transformed with a plasmid construct containing IgFAD2 could convert endogenous oleic acid(18:1^(?9), OA) into linoleic acid(18:2^(?9, 12), LA). These findings confirm that I. galbana IgFAD2 plays important roles in the biosynthetic pathways of unsaturated fatty acids.展开更多
Phenol is a common industrial chemical produced and transported worldwide largely.Therefore,accidental spillage of phenol in the ocean causes an increasing concern.Microalgae are promising to remove phenol from marine...Phenol is a common industrial chemical produced and transported worldwide largely.Therefore,accidental spillage of phenol in the ocean causes an increasing concern.Microalgae are promising to remove phenol from marine waters.However,temperature and light intensity are two main factors that markedly influence biodegradation in marine environments.In this study,a marine golden alga Isochrysis galbana is selected to research the removal of phenol under different temperatures(10-30℃)and light intensities(0-240μmol/(m^2·s)).The results show that the most suitable temperature and light intensity for phenol removal are 20℃and 180μmol/(m2·s),respectively,and 100 mg/L of phenol can be completely removed by microalga in 24 h at these conditions.I.galbana can also remove phenol under dark and low-temperature conditions.The removal of phenol by I.galbana at diverse temperatures and light intensities conform to first-order kinetics,and the process under dark conditions conform to zero-order kinetics.Thus,I.galbana can be used in the in-situ bioremediation of polluted seawater by phenol.展开更多
Marine microalga Isochrysis galbana is an important feed species with a high nutritional value.Different from other uni-cellular algae,its cell contains two chloroplasts which are the major sites for lipid synthesis.H...Marine microalga Isochrysis galbana is an important feed species with a high nutritional value.Different from other uni-cellular algae,its cell contains two chloroplasts which are the major sites for lipid synthesis.Here,we optimized a chloroplast isola-tion approach suitable for the isolation of I.galbana chloroplasts and determined the purity and integrity of the isolated chloroplasts through microscopic observations and enzyme activity assay.The chloroplast lipids were analyzed with a ultrahigh-performance li-quid chromatography-Q Exactive Orbitrap-mass spectrometry.This newly developed isolation approach is simple and reliable to isolate chloroplasts with high integrity and purity.The average yield of intact chloroplasts was 15.3%±0.1%.Glycolipids and acyl-glycerols were the main chloroplast lipids.Glycolipids accounted for 56.6%of chloroplast lipid.Digalactosyldiacylglycerol(DGDG),monogalactosyldiacylglycerol(MGDG)and sulfoquinovosyldiacylglycerol(SQDG)were the main glyceroglycolipids.The fatty acyl R1/R2 were mostly 18:4/16:1,18:3/16:1 and 18:4/18:5 in DGDGs,14:0/18:4,18:4/18:5,18:4/18:4 and 18:3/18:4 in MGDGs and 16:0/14:0,16:0/18:3,and 18:4/18:3 in SQDGs.In addition,diacylglycerol(DAG)was the most abundant acylglycerols;the content of 22:6/18:4-DAG was the highest.There was a little amount of glycosphingolipid(GSL)in chloroplast.Digalactosylmonoglyceride(DGMG),monogalactosylmonoglyceride(MGMG),sulfoquinovosylmonoacylglycerol(SQMG),monoglyceride(MAG),phospholi-pids(PLs),ceramide(Cer)and betaine lipids were nearly undetectable in chloroplast.The fatty acid proportions of DGDGs,MGDGs,SQDGs,DAGs,triglycerides(TAGs)and GSLs were either higher or lower than or similar to those of whole-cell.Collectively,our isolation approach is applicable to many aspects of chloroplast biology,and may offer a reference for the isolation of chloroplasts from other marine microalgae.展开更多
Isochrysis galbana is considered an ideal bait for functional foods and nutraceuticals of humans because of its high fucoxanthin(Fx)content.However,multi-omics analysis of the regulatory networks for Fx biosynthesis i...Isochrysis galbana is considered an ideal bait for functional foods and nutraceuticals of humans because of its high fucoxanthin(Fx)content.However,multi-omics analysis of the regulatory networks for Fx biosynthesis in I.galbana has not been reported.In this study,we report a high-quality genome assembly of I.galbana LG007,which has a genome size of 92.73 Mb,with a contig N50 of 6.99 Mb and 14,900 protein-coding genes.Phylogenetic analysis confirmed the monophyly of Haptophyta,with I.galbana sister to Emiliania huxleyi and Chrysochromulina tobinii.Evolutionary analysis revealed an estimated divergence time between I.galbana and E.huxleyi of~133 million years ago.Gene family analysis indicated that lipid metabolism-related genes exhibited significant expansion,including IgPLMT,IgOAR1,and IgDEGS1.Metabolome analysis showed that the content of carotenoids in I.galbana cultured under green light for 7 days was higher than that under white light,andβ-carotene was the main carotenoid,accounting for 79.09%of the total carotenoids.Comprehensive multi-omics analysis revealed that the content ofβ-carotene,antheraxanthin,zeaxanthin,and Fx was increased by green light induction,which was significantly correlated with the expression of IgMYB98,IgZDS,IgPDS,IgLHCX2,IgZEP,IgLCYb,and IgNSY.These findings contribute to the understanding of Fx biosynthesis and its regulation,providing a valuable reference for food and pharmaceutical applications.展开更多
Objective:To study the effect of species of lactic acid bacteria(LAB)from telluric origin on the growth of the microalgae Isochrysis galbana(I.galbana)in small and medium volume flasks.Methods:In the first experiment,...Objective:To study the effect of species of lactic acid bacteria(LAB)from telluric origin on the growth of the microalgae Isochrysis galbana(I.galbana)in small and medium volume flasks.Methods:In the first experiment,7 LAB species[Carnobacterium piscicola,Lactobacillus brevis,Lactobacillus casei ssp.casei,Lactobacillus helveticus,Lactococcus lactis spp.lactis,Leuconostoc mesenteroides spp.mesenteroides(L.mesenteroides spp.mesenteroides)and Pediococcus acidilactici(P.acidilactici)]were inoculated in 250 mL flasks containing microalgae I.galbana(10^(6)cells/mL).After fitting the growth data to two mathematical models,two LAB strains(L.mesenteroides spp.mesenteroides and P.acidilactici)were selected for the second experiment in which those strains were inoculated in medium size(5 L)volume cultures of I.galbana(1.2×10^(5)-1.5×10^(5)cells/mL).The bacterial load in cultures from the first experiment was analyzed by plating on marine agar,MRS agar and thiosulfate citrate bile saltssucrose media.Results:All strains of LAB tested enhanced the growth rate and the final biomass yield of I.galbana cultures,even in the absence of nutrients in the media.The best overall results and the maximal final cell densities in small flasks were achieved with strains L.mesenteroides spp.mesenteroides and P.acidilactici,respectively.These two strains also stimulated the growth(40%and 16%with respect to controls)of I.galbana in medium size volumes.For most strains,CFU values of LAB remained stable(10^(5)-10^(8)CFU/mL)for at least 4 days.A high variability was observed in bacteria strains among treatments,with Pseudomonas and Moraxella being the most abundant bacteria.Conclusions:The results of present study showed that the growth of I.galbana in both small and medium size volumes was enhanced by LAB,both in the absence and the presence of nutrients in the culture.The highest final biomass was achieved by adding P.acidilactici,whereas Carnobacterium piscicola and L.mesenteroides spp.mesenteroides provided maximal growth rates.The former also showed an inhibitory effect on Moraxella.展开更多
Biological CO2 sequestration by microalgae is a promising and environmentally friendly technology applied to sequester CO2. The characteristics of neutral lipid accumulation by two marine oil-rich microalgal strains,n...Biological CO2 sequestration by microalgae is a promising and environmentally friendly technology applied to sequester CO2. The characteristics of neutral lipid accumulation by two marine oil-rich microalgal strains,namely, Isochrysis galbana and Nannochloropsis sp., through CO2 enrichment cultivation were investigated in this study. The optimum culture conditions of the two microalgal strains are 10% CO2 and f medium. The maximum biomass productivity, total lipid content, maximum lipid productivity, carbon content, and CO2 fixation ability of the two microalgal strains were obtained. The corresponding parameters of the two strains were as follows：（（142.42±4.58） g/（m^2·d）,（149.92±1.80） g/（m^2·d））,（（39.95±0.77）%,（37.91±0.58）%）,（（84.47±1.56） g/（m^2·d）,（89.90±1.98） g/（m^2·d））,（（45.98±1.75）%,（46.88±2.01）%）, and（（33.74±1.65） g/（m^2·d）,（34.08±1.32） g/（m^2·d））. Results indicated that the two marine microalgal strains with high CO2 fixation ability are potential strains for marine biodiesel development coupled with CO2 emission reduction.展开更多
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LY22C190001)the Natural Science Foundation of Ningbo Government(No.2021J114)+3 种基金the Ningbo Science and Technology Research Projects,China(No.2019B10006)the Zhejiang Provincial Department of Education Scientific Research Project(No.Y202249030)the Earmarked Fund for CARS-49partly sponsored by K.C.Wong Magna Fund in Ningbo University.
文摘Gamma-aminobutyric acid(GABA),widely existing in different organisms,is rapidly accumulated in plants in response to environmental stresses.The main biosynthesis and degradation pathways of GABA constitute the GABA shunt,which is tied to the tricarboxylic acid(TCA)cycle.GABA transaminase(GABA-T)and succinate semialdehyde dehydrogenase(SSADH)are two essential enzymes for the GABA degradation pathway.While there are abundant studies on GABA shunt in higher plants at the physiological and genetic levels,research on its role in microalgae remains limited.This study aimed at exploring the function of GABA-T and SSADH genes in Isochrysis zhanjiangensis,an important diet microalga,under different stresses.We cloned two GABA-T genes,IzGABA-T1 and IzGABA-T2,and one SSADH gene IzSSADH from Isochrysis zhanjiangensis and conducted heterologous expression experiments.The results showed that the overexpression of IzGABA-T1 or IzGABA-T2 enhanced the survival rates of yeast transformants under heat or NaCl stress,while the overexpression of IzSSADH improved yeast tolerance to NaCl stress but had no obvious effect on heat stress.Additionally,the results of quantitative real-time polymerase chain reaction(qPCR)showed that IzGABA-T1 transcription increased in the HT(salinity 25,35℃)and LS(salinity 15,25℃)groups.At 24 h,the IzGABA-T2 transcriptions increased in the HT,LS,and HS(salinity 35,25℃)groups,but their transcription levels decreased in all groups at 48 h.IzSSADH transcription increased in the LS group.These results suggest that IzGABA-T1,IzGABA-T2,and IzSSADH are associated with temperature and salinity stresses and possess a certain preference for different stresses.
基金The Basic Scientific Fund for National Public Research Institutes of China under contract No.2017Q09the Aoshan Science and Technology Innovation Project of Pilot National Laboratory for Marine Science and Technology(Qingdao)under contract No.2016ASKJ02+3 种基金the National Natural Science Foundation of China-Shandong Joint Funded Project under contract No.U1606404the National Natural Science Foundation of China under contract Nos 41776176 and 41806201the 973 Project from Chinese Ministry of Science and Technology under contract No.2015CB755904the Shandong Provincial Natural Science Foundation under contract No.ZR2015PD003
文摘The cDNA of the delta-12 fatty acid desaturase gene, IgFAD2, was cloned from the marine microalgae Isochrysis galbana, a species capable of producing docosahexaenoic acid. Sequence analysis indicated that the open reading frame measured a length of 1 158 bp and encoded 386 amino acids with a predicted molecular weight of 42.8 kDa and an isoelectric point of 9.2. Computational analysis of the protein sequence of IgFAD2 showed typical features of membrane-bound desaturase such as three conserved histidine boxes along with four membranespanning regions that were universally present among plant desaturases. Quantitative real-time PCR results showed that the abundance of IgFAD2 transcript was significantly upregulated under different environmental stresses including low temperature(15℃), high salinity(salinity of 62 and 93), and nitrogen starvation(220 μmol/L). Heterologous expression indicated that yeast cells transformed with a plasmid construct containing IgFAD2 could convert endogenous oleic acid(18:1^(?9), OA) into linoleic acid(18:2^(?9, 12), LA). These findings confirm that I. galbana IgFAD2 plays important roles in the biosynthetic pathways of unsaturated fatty acids.
基金Supported by the National Marine Hazard Mitigation Service,Ministry of Natural Resource of the People’s Republic of China through its Commissioned Research Scheme(No.2018AA019)。
文摘Phenol is a common industrial chemical produced and transported worldwide largely.Therefore,accidental spillage of phenol in the ocean causes an increasing concern.Microalgae are promising to remove phenol from marine waters.However,temperature and light intensity are two main factors that markedly influence biodegradation in marine environments.In this study,a marine golden alga Isochrysis galbana is selected to research the removal of phenol under different temperatures(10-30℃)and light intensities(0-240μmol/(m^2·s)).The results show that the most suitable temperature and light intensity for phenol removal are 20℃and 180μmol/(m2·s),respectively,and 100 mg/L of phenol can be completely removed by microalga in 24 h at these conditions.I.galbana can also remove phenol under dark and low-temperature conditions.The removal of phenol by I.galbana at diverse temperatures and light intensities conform to first-order kinetics,and the process under dark conditions conform to zero-order kinetics.Thus,I.galbana can be used in the in-situ bioremediation of polluted seawater by phenol.
基金supported by the Ningbo Science and Technology Research Projects(No.2019B10006)the Na-tional Key Research and Development Program of China(No.2019YFD0900400)+3 种基金the Zhejiang Major Science Pro-ject(No.2019C02057)the China Agriculture Research System of MOF and MARA,the Natural Science Founda-tion of Ningbo(No.2019A610416)the Ningbo Science and Technology Research Projects(No.2019C10023)the National Natural Science Foundation of China(No.31801724).
文摘Marine microalga Isochrysis galbana is an important feed species with a high nutritional value.Different from other uni-cellular algae,its cell contains two chloroplasts which are the major sites for lipid synthesis.Here,we optimized a chloroplast isola-tion approach suitable for the isolation of I.galbana chloroplasts and determined the purity and integrity of the isolated chloroplasts through microscopic observations and enzyme activity assay.The chloroplast lipids were analyzed with a ultrahigh-performance li-quid chromatography-Q Exactive Orbitrap-mass spectrometry.This newly developed isolation approach is simple and reliable to isolate chloroplasts with high integrity and purity.The average yield of intact chloroplasts was 15.3%±0.1%.Glycolipids and acyl-glycerols were the main chloroplast lipids.Glycolipids accounted for 56.6%of chloroplast lipid.Digalactosyldiacylglycerol(DGDG),monogalactosyldiacylglycerol(MGDG)and sulfoquinovosyldiacylglycerol(SQDG)were the main glyceroglycolipids.The fatty acyl R1/R2 were mostly 18:4/16:1,18:3/16:1 and 18:4/18:5 in DGDGs,14:0/18:4,18:4/18:5,18:4/18:4 and 18:3/18:4 in MGDGs and 16:0/14:0,16:0/18:3,and 18:4/18:3 in SQDGs.In addition,diacylglycerol(DAG)was the most abundant acylglycerols;the content of 22:6/18:4-DAG was the highest.There was a little amount of glycosphingolipid(GSL)in chloroplast.Digalactosylmonoglyceride(DGMG),monogalactosylmonoglyceride(MGMG),sulfoquinovosylmonoacylglycerol(SQMG),monoglyceride(MAG),phospholi-pids(PLs),ceramide(Cer)and betaine lipids were nearly undetectable in chloroplast.The fatty acid proportions of DGDGs,MGDGs,SQDGs,DAGs,triglycerides(TAGs)and GSLs were either higher or lower than or similar to those of whole-cell.Collectively,our isolation approach is applicable to many aspects of chloroplast biology,and may offer a reference for the isolation of chloroplasts from other marine microalgae.
基金supported by the National Natural Science Foundation of China(Grant No.42006087)the Sugar Crop Research System,China(Grant No.CARS-170501).
文摘Isochrysis galbana is considered an ideal bait for functional foods and nutraceuticals of humans because of its high fucoxanthin(Fx)content.However,multi-omics analysis of the regulatory networks for Fx biosynthesis in I.galbana has not been reported.In this study,we report a high-quality genome assembly of I.galbana LG007,which has a genome size of 92.73 Mb,with a contig N50 of 6.99 Mb and 14,900 protein-coding genes.Phylogenetic analysis confirmed the monophyly of Haptophyta,with I.galbana sister to Emiliania huxleyi and Chrysochromulina tobinii.Evolutionary analysis revealed an estimated divergence time between I.galbana and E.huxleyi of~133 million years ago.Gene family analysis indicated that lipid metabolism-related genes exhibited significant expansion,including IgPLMT,IgOAR1,and IgDEGS1.Metabolome analysis showed that the content of carotenoids in I.galbana cultured under green light for 7 days was higher than that under white light,andβ-carotene was the main carotenoid,accounting for 79.09%of the total carotenoids.Comprehensive multi-omics analysis revealed that the content ofβ-carotene,antheraxanthin,zeaxanthin,and Fx was increased by green light induction,which was significantly correlated with the expression of IgMYB98,IgZDS,IgPDS,IgLHCX2,IgZEP,IgLCYb,and IgNSY.These findings contribute to the understanding of Fx biosynthesis and its regulation,providing a valuable reference for food and pharmaceutical applications.
基金Supported by European Commission(Project PROBE,Q5RS-2000-31457)CICYT(Spain,FEDER,1FD97-0044-C03-01,02 and 03)Dr.J.A.Vázquez Álvarez had a postdoctoral contract(CSIC-I3P-PC 2003,European Social Fund).
文摘Objective:To study the effect of species of lactic acid bacteria(LAB)from telluric origin on the growth of the microalgae Isochrysis galbana(I.galbana)in small and medium volume flasks.Methods:In the first experiment,7 LAB species[Carnobacterium piscicola,Lactobacillus brevis,Lactobacillus casei ssp.casei,Lactobacillus helveticus,Lactococcus lactis spp.lactis,Leuconostoc mesenteroides spp.mesenteroides(L.mesenteroides spp.mesenteroides)and Pediococcus acidilactici(P.acidilactici)]were inoculated in 250 mL flasks containing microalgae I.galbana(10^(6)cells/mL).After fitting the growth data to two mathematical models,two LAB strains(L.mesenteroides spp.mesenteroides and P.acidilactici)were selected for the second experiment in which those strains were inoculated in medium size(5 L)volume cultures of I.galbana(1.2×10^(5)-1.5×10^(5)cells/mL).The bacterial load in cultures from the first experiment was analyzed by plating on marine agar,MRS agar and thiosulfate citrate bile saltssucrose media.Results:All strains of LAB tested enhanced the growth rate and the final biomass yield of I.galbana cultures,even in the absence of nutrients in the media.The best overall results and the maximal final cell densities in small flasks were achieved with strains L.mesenteroides spp.mesenteroides and P.acidilactici,respectively.These two strains also stimulated the growth(40%and 16%with respect to controls)of I.galbana in medium size volumes.For most strains,CFU values of LAB remained stable(10^(5)-10^(8)CFU/mL)for at least 4 days.A high variability was observed in bacteria strains among treatments,with Pseudomonas and Moraxella being the most abundant bacteria.Conclusions:The results of present study showed that the growth of I.galbana in both small and medium size volumes was enhanced by LAB,both in the absence and the presence of nutrients in the culture.The highest final biomass was achieved by adding P.acidilactici,whereas Carnobacterium piscicola and L.mesenteroides spp.mesenteroides provided maximal growth rates.The former also showed an inhibitory effect on Moraxella.
基金The Basic Scientific Fund for National Public Research Institutes of China under contract Nos 2017Q09 and2016Q02the National Natural Science Foundation of China under contract No.41776176+2 种基金the National Key Research and Development Program of China under contract No.2017YFC1404604the Shandong Provincial Natural Science Foundation under contract No.ZR2015PD003the 2012 Taishan Scholar
文摘Biological CO2 sequestration by microalgae is a promising and environmentally friendly technology applied to sequester CO2. The characteristics of neutral lipid accumulation by two marine oil-rich microalgal strains,namely, Isochrysis galbana and Nannochloropsis sp., through CO2 enrichment cultivation were investigated in this study. The optimum culture conditions of the two microalgal strains are 10% CO2 and f medium. The maximum biomass productivity, total lipid content, maximum lipid productivity, carbon content, and CO2 fixation ability of the two microalgal strains were obtained. The corresponding parameters of the two strains were as follows：（（142.42±4.58） g/（m^2·d）,（149.92±1.80） g/（m^2·d））,（（39.95±0.77）%,（37.91±0.58）%）,（（84.47±1.56） g/（m^2·d）,（89.90±1.98） g/（m^2·d））,（（45.98±1.75）%,（46.88±2.01）%）, and（（33.74±1.65） g/（m^2·d）,（34.08±1.32） g/（m^2·d））. Results indicated that the two marine microalgal strains with high CO2 fixation ability are potential strains for marine biodiesel development coupled with CO2 emission reduction.
