Cold stress promoting a psychrotolerant bacterium <Emphasis Type="Italic">Pseudomonas</Emphasis><Emphasis Type="Italic">fragi</Emphasis> P121 producing trehaloase |
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Authors: | Yan-Zhen Mei Peng-Wei Huang Yang Liu Wei He Wen-Wan Fang |
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Institution: | 1.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,China;2.College of Life Science,Inner Mongolia University,Hohhot,China |
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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. |
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