Phosphorus concentration on the surface of seawater varies greatly with different environments,especially in coastal.The molecular mechanism by which cyanobacteria adapt to fluctuating phosphorus bioavailability is st...Phosphorus concentration on the surface of seawater varies greatly with different environments,especially in coastal.The molecular mechanism by which cyanobacteria adapt to fluctuating phosphorus bioavailability is still unclear.In this study,transcriptomes and gene knockouts were used to investigate the adaptive molecular mechanism of a model coastal cyanobacterium Synechococcus sp.PCC 7002 during periods of phosphorus starvation and phosphorus recovery(adding sufficient phosphorus after phosphorus starvation).The findings indicated that phosphorus deficiency affected the photosynthesis,ribosome synthesis,and bacterial motility pathways,which recommenced after phosphorus was resupplied.Even more,most of the metabolic pathways of cyanobacteria were enhanced after phosphorus recovery compared to the control which was kept in continuous phosphorus replete conditions.Based on transcriptome,54 genes potentially related to phosphorusdeficiency adaptation were selected and knocked out individually or in combination.It was found that five mutants showed weak growth phenotype under phosphorus deficiency,indicating the importance of the genes(A0076,A0549-50,A1094,A1320,A1895)in the adaptation of phosphorus deficiency.Three mutants were found to grow better than the wild type under phosphorus deficiency,suggesting that the products of these genes(A0079,A0340,A2284–86)might influence the adaptation to phosphorus deficiency.Bioinformatics analysis revealed that cyanobacteria exposed to highly fluctuating phosphorus concentrations have more sophisticated phosphorus acquisition strategies.These results elucidated that Synechococcus sp.PCC 7002 have variable phosphorus response mechanisms to adapt to fluctuating phosphorus concentration,providing a novel perspective of how cyanobacteria may respond to the complex and dynamic environments.展开更多
Genetic modifi cation is useful for improving the nutritional qualities of cyanobacteria. To increase the total unsaturated fatty acid content, along with the ratio of ω-3/ω-6 fatty acids, genetic engineering can be...Genetic modifi cation is useful for improving the nutritional qualities of cyanobacteria. To increase the total unsaturated fatty acid content, along with the ratio of ω-3/ω-6 fatty acids, genetic engineering can be used to modify fatty acid metabolism. S ynechococcus sp. PCC7002, a fast-growing cyanobacterium, does not contain a Δ6 desaturase gene and is therefore unable to synthesize γ-linolenic acid(GLA) and stearidonic acid(SDA), which are important in human health. In this work, we constructed recombinant vectors Syd6 D, Syd15 D and Syd6Dd15 D to express the Δ15 desaturase and Δ6 desaturase genes from Synechocystis PCC6803 in Synechococcus sp. PCC7002, with the aim of expressing polyunsaturated fatty acids. Overexpression of the Δ15 desaturase gene in S ynechococcus resulted in 5.4 times greater accumulation of α-linolenic acid compared with the wild-type while Δ6 desaturase gene expression produced both GLA and SDA. Co-expression of the two genes resulted in low-level accumulation of GLA but much larger amounts of SDA, accounting for as much to 11.64% of the total fatty acid content.展开更多
In transgenic process, a foreign gene can be integrated in the host genome in two directions, which may influence its expression. In order to study the effects of insertal orientation, the gfp reporter gene was insert...In transgenic process, a foreign gene can be integrated in the host genome in two directions, which may influence its expression. In order to study the effects of insertal orientation, the gfp reporter gene was inserted in the isiAB locus of Synechococcus sp. PCC7942 in different directions, and the GFP expression levels and the growth of the transgenic algae were compared. It was showed that the gfp gene could express in each direction, and no significant difference was detected on algal growth and GFP expression levels between the two recombinant algae.展开更多
基金the support from Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai,No.SML2021SP204)funded by the National Natural Science Founda-tion of China(Grant Nos.32170108,and 42188102)+1 种基金the Science and Technology Innovation 2025 Major Project of Ningbo City(Grant No.2022Z189)the Ningbo Public Welfare Science and Technology Program(Grant Nos.2023S068,2023S040).
文摘Phosphorus concentration on the surface of seawater varies greatly with different environments,especially in coastal.The molecular mechanism by which cyanobacteria adapt to fluctuating phosphorus bioavailability is still unclear.In this study,transcriptomes and gene knockouts were used to investigate the adaptive molecular mechanism of a model coastal cyanobacterium Synechococcus sp.PCC 7002 during periods of phosphorus starvation and phosphorus recovery(adding sufficient phosphorus after phosphorus starvation).The findings indicated that phosphorus deficiency affected the photosynthesis,ribosome synthesis,and bacterial motility pathways,which recommenced after phosphorus was resupplied.Even more,most of the metabolic pathways of cyanobacteria were enhanced after phosphorus recovery compared to the control which was kept in continuous phosphorus replete conditions.Based on transcriptome,54 genes potentially related to phosphorusdeficiency adaptation were selected and knocked out individually or in combination.It was found that five mutants showed weak growth phenotype under phosphorus deficiency,indicating the importance of the genes(A0076,A0549-50,A1094,A1320,A1895)in the adaptation of phosphorus deficiency.Three mutants were found to grow better than the wild type under phosphorus deficiency,suggesting that the products of these genes(A0079,A0340,A2284–86)might influence the adaptation to phosphorus deficiency.Bioinformatics analysis revealed that cyanobacteria exposed to highly fluctuating phosphorus concentrations have more sophisticated phosphorus acquisition strategies.These results elucidated that Synechococcus sp.PCC 7002 have variable phosphorus response mechanisms to adapt to fluctuating phosphorus concentration,providing a novel perspective of how cyanobacteria may respond to the complex and dynamic environments.
基金Supported by the International S&T Cooperation Program of China(No.2012DFA30450)the National Natural Science Foundation of China(No.30871541)+1 种基金the Taishan Scholar Foundation of Shandong Province(No.tshw20091014)the Innovation Program of the University Institutes of Jinan,Shandong Province(No.201004044)
文摘Genetic modifi cation is useful for improving the nutritional qualities of cyanobacteria. To increase the total unsaturated fatty acid content, along with the ratio of ω-3/ω-6 fatty acids, genetic engineering can be used to modify fatty acid metabolism. S ynechococcus sp. PCC7002, a fast-growing cyanobacterium, does not contain a Δ6 desaturase gene and is therefore unable to synthesize γ-linolenic acid(GLA) and stearidonic acid(SDA), which are important in human health. In this work, we constructed recombinant vectors Syd6 D, Syd15 D and Syd6Dd15 D to express the Δ15 desaturase and Δ6 desaturase genes from Synechocystis PCC6803 in Synechococcus sp. PCC7002, with the aim of expressing polyunsaturated fatty acids. Overexpression of the Δ15 desaturase gene in S ynechococcus resulted in 5.4 times greater accumulation of α-linolenic acid compared with the wild-type while Δ6 desaturase gene expression produced both GLA and SDA. Co-expression of the two genes resulted in low-level accumulation of GLA but much larger amounts of SDA, accounting for as much to 11.64% of the total fatty acid content.
基金supported Science Foundation of China by the National Natural(No.30471317).
文摘In transgenic process, a foreign gene can be integrated in the host genome in two directions, which may influence its expression. In order to study the effects of insertal orientation, the gfp reporter gene was inserted in the isiAB locus of Synechococcus sp. PCC7942 in different directions, and the GFP expression levels and the growth of the transgenic algae were compared. It was showed that the gfp gene could express in each direction, and no significant difference was detected on algal growth and GFP expression levels between the two recombinant algae.
