title: Cold stress promoting a psychrotolerant bacterium Pseudomonas fragi P121 producing trehaloase.
abstract: A newly isolated Pseudomonas fragi P121 strain in a soil sample taken from the Arctic Circle is able to produce trehalose. The P121 strain was able to grow at temperatures ranging from 4 to 25 °C, had an optimum pH of 6.5, and an optimum salt concentration of 2 %. The P121 strain had a survival rate of 29.1 % after being repeatedly frozen and thawed five times, and a survival rate of 78.9 % when placed in physiological saline for 15 days at 20 °C after cold shock, which is far higher than the type strain Pseudomonas fragi ATCC 4973. The P121 strain could produce 2.89 g/L trehalose, which was 18.6 % of dry cell weight within 52 h in a 25 L fermention tank using the malt extract prepared from barley as medium at 15 °C, while only 11.8 % of dry cell weight at 20 °C. These results suggested that cold stress promoted the strain producing trehalose. It is the first reported cold-tolerant bacterium that produces trehalose, which may protect cells against the cold environment.
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science, Nanjing Normal University, Nanjing, 210023, Jiangsu Province, China. 08279@njnu.edu.cn.
authors.forename: Yan-Zhen
authors.initials: YZ
authors.lastname: Mei
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science, Nanjing Normal University, Nanjing, 210023, Jiangsu Province, China.
authors.forename: Peng-Wei
authors.initials: PW
authors.lastname: Huang
authors.affiliation: College of Life Science, Inner Mongolia University, Hohhot, 010021, Inner Mongolia, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science, Nanjing Normal University, Nanjing, 210023, Jiangsu Province, China.
authors.forename: Wei
authors.initials: W
authors.lastname: He
authors.affiliation: Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science, Nanjing Normal University, Nanjing, 210023, Jiangsu Province, China.
authors.forename: Wen-Wan
authors.initials: WW
authors.lastname: Fang
mesh_terms: D000864:Antarctic Regions; D003080:Cold Temperature; D005285:Fermentation; D044206:Pseudomonas fragi / Q000254:growth & development* / Q000302:isolation & purification*; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013312:Stress, Physiological; D014199:Trehalose / Q000378:metabolism*
chemical_list: D014199:Trehalose
keywords: Barley; Freeze–thaw resistance; Pseudomonas fragi P121; Psychrotolerant bacterium; Purification; Trehalose