Expression and enzymatic characterization of a cold-adapted β-agarase from Antarctic bacterium Pseudoalteromonas sp.NJ21  

作　　者：李江 沙玉杰 

机构地区：[1]Key Lab of Marine Bioactive Substances,First Institute of Oceanography,State Oceanic Administration (SOA) [2]Institute of Oceanology,Chinese Academy of Sciences

出　　处：《Chinese Journal of Oceanology and Limnology》2015年第2期319-327,共9页中国海洋湖沼学报（英文版）

基　　金：Supported by the Public Science and Technology Research Funds Project of Ocean(No.201105027);the Shandong Province Young and the Middle-Aged Scientists Research Awards Fund(No.DS2010HZ001);the Basic Scientific Research Funds of First Institute of Oceanography,State Oceanic Administration(No.GY02-2011G17)

摘　　要：An agar-degrading bacterium, designated as Pseudoalteromonas sp. NJ21, was isolated from an Antarctic sediment sample. The agarase gene aga1161 from Pseudoalteromonas sp. NJ21 consisting of a 2 382-bp coding region was cloned. The gene encodes a 793-amino acids protein and was found to possess characteristic features of the Glyco_hydro 42 family. The recombinant agarase （rAgal 161） was overexpressed in Escherichia coli and purified as a fusion protein. Enzyme activity analysis revealed that the optimum temperature and pH for the purified recombinant agarase were 30--40℃ and 8.0, respectively. rAga 1161 was found to maintain as much as 80% of its maximum activity at 10℃, which is typical of a cold- adapted enzyme. The pattern of agar hydrolysis demonstrated that the enzyme is an β-agarase, producing neoagarobiose （NA2） as the final main product. Furthermore, this work is the first proof of an agarolytic activity in Antarctic bacteria and these results indicate the potential for the Antarctic agarase as a catalyst in medicine, food and cosmetic industries.An agar-degrading bacterium,designated as Pseudoalteromonas sp. NJ21,was isolated from an Antarctic sediment sample. The agarase gene a ga1161 from Pseudoalteromonas sp. NJ21 consisting of a 2 382-bp coding region was cloned. The gene encodes a 793-amino acids protein and was found to possess characteristic features of the Glyco_hydro_42 family. The recombinant agarase(r Aga1161) was overexpressed in Escherichia coli and purified as a fusion protein. Enzyme activity analysis revealed that the optimum temperature and pH for the purified recombinant agarase were 30–40°C and 8.0,respectively. rAga1161 was found to maintain as much as 80% of its maximum activity at 10°C,which is typical of a coldadapted enzyme. The pattern of agar hydrolysis demonstrated that the enzyme is an β-agarase,producing neoagarobiose(NA2) as the final main product. Furthermore,this work is the first proof of an agarolytic activity in Antarctic bacteria and these results indicate the potential for the Antarctic agarase as a catalyst in medicine,food and cosmetic industries.

关 键 词：Antarctic bacterium Pseudoalteromonas AGARASE EXPRESSION enzymatic characterization 

分 类 号：S917.1[农业科学—水产科学]