Versatility of a psychrotolerant Pseudoalteromonas sp.BSw20308 from the Arctic Ocean as revealed by biochemical characterization and genome sequencing

【作者】 曾胤新； 廖丽； 俞勇；

【Author】 Yin-Xin Zeng Li Liao Yong Yu Polar Research Institute of China,Shanghai,China

【机构】 Polar Research Institute of China；

【摘要】 <正>Abstract:The genus Pseudoalteromonas,ubiquitous in the marine environments,accounts for a significant fraction of culturable bacteria isolated from cold marine environments.Previously,we isolated a psychrotolerant strain,Pseudoalteromonas sp.BSw20308,from seawater of the Chukchi Sea.It was shown to utilize multiple carbon/ nitrogen sources,and can adapt to low temperature(below 0℃to optimum at 15℃).To investigate its ecological role and adaptation to low temperature,here we report the characterization and genome sequencing of Pseudoalteromonas sp.BSw20308. Strain BSw20308 was shown to form black pigment on plate and produce various extracellular enzymes,including agarase,amylase,cellulase,lipase and protease,to utilize environmental polysaccharides and proteins for nutrients.The draft genome,sequenced on Genome Sequencer FLX,was assembled to be 4.76 Mb,containing 146 contigs(= 500 bp) with an average G+C content of 38.9%.A total of 4,172 ORFs were predicted,including 3,109 ORFs(74.5%) assigned to COG categories,and 1,991 ORFs(47.7%>) found in the KEGG database.A significant amount of COGs belonged to amino acid(9.5%) and carbohydrate(6.6%) transport and metabolism.In addition,2.3%of COGs were classified into secondary metabolite biosynthesis.As analyzed in KEGG database,296 and 268 ORFs were involved in carbohydrate and amino acid metabolism respectively,making them the dominant function encoded in the genome as predicted.Hence,it suggests the importance of protein and carbohydrate metabolism in strain BSw20308,consistent with the ability to produce various extracellular proteolytic enzymes and glycoside hydrases to live on multiple carbon and nitrogen sources.Further annotation revealed multiple genes encoding same glycoside hydrases with different substrate specificity to enable degradation of a full range of substrates,e.g.,multiple agarases and glucanases from GH16 family.In addition,signal transduction and secondary metabolite biosynthesis were two important functions according to KEGG classification as well. Proteins responsible for producing and tailoring natural products including multiple halogenases, cytochrome P450,NRPS(Nonribosomal peptides synthase) and melanin synthesizing enzyme were annotated,indicating its potential biotechnological applications.Cold adaptation of strain BSw20308 was reflected in its genetic context,e.g.,genes for unsaturated fatty acid synthesis and cold shock proteins. Hence,the genome of Pseudoalteromonas sp.BSw20308 provided the explanation of its versatility and cold adaptation from the genetic point of view.It also revealed the potential function in ecology and application in biotechnology.In addition,comparison with other genomes previously published in this genus may help define the core for common function/physiology and varying regions responsible for individual adaptation.Therefore,it is also significant in understanding genome evolution.更多还原

【Abstract】 Abstract:The genus Pseudoalteromonas,ubiquitous in the marine environments,accounts for a significant fraction of culturable bacteria isolated from cold marine environments.Previously,we isolated a psychrotolerant strain,Pseudoalteromonas sp.BSw20308,from seawater of the Chukchi Sea.It was shown to utilize multiple carbon/ nitrogen sources,and can adapt to low temperature(below 0℃to optimum at 15℃).To investigate its ecological role and adaptation to low temperature,here we report the characterization and genome sequencing of Pseudoalteromonas sp.BSw20308. Strain BSw20308 was shown to form black pigment on plate and produce various extracellular enzymes,including agarase,amylase,cellulase,lipase and protease,to utilize environmental polysaccharides and proteins for nutrients.The draft genome,sequenced on Genome Sequencer FLX,was assembled to be 4.76 Mb,containing 146 contigs(= 500 bp) with an average G+C content of 38.9%.A total of 4,172 ORFs were predicted,including 3,109 ORFs(74.5%) assigned to COG categories,and 1,991 ORFs(47.7%>) found in the KEGG database.A significant amount of COGs belonged to amino acid(9.5%) and carbohydrate(6.6%) transport and metabolism.In addition,2.3%of COGs were classified into secondary metabolite biosynthesis.As analyzed in KEGG database,296 and 268 ORFs were involved in carbohydrate and amino acid metabolism respectively,making them the dominant function encoded in the genome as predicted.Hence,it suggests the importance of protein and carbohydrate metabolism in strain BSw20308,consistent with the ability to produce various extracellular proteolytic enzymes and glycoside hydrases to live on multiple carbon and nitrogen sources.Further annotation revealed multiple genes encoding same glycoside hydrases with different substrate specificity to enable degradation of a full range of substrates,e.g.,multiple agarases and glucanases from GH16 family.In addition,signal transduction and secondary metabolite biosynthesis were two important functions according to KEGG classification as well. Proteins responsible for producing and tailoring natural products including multiple halogenases, cytochrome P450,NRPS(Nonribosomal peptides synthase) and melanin synthesizing enzyme were annotated,indicating its potential biotechnological applications.Cold adaptation of strain BSw20308 was reflected in its genetic context,e.g.,genes for unsaturated fatty acid synthesis and cold shock proteins. Hence,the genome of Pseudoalteromonas sp.BSw20308 provided the explanation of its versatility and cold adaptation from the genetic point of view.It also revealed the potential function in ecology and application in biotechnology.In addition,comparison with other genomes previously published in this genus may help define the core for common function/physiology and varying regions responsible for individual adaptation.Therefore,it is also significant in understanding genome evolution.更多还原