Yumoto Isao, Hirota Kikue, Iwata Hideaki, Akutsu Masatoshi, Kusumoto Keita, Morita Naoki, Ezura Yoshio, Okuyama Hidetoshi, Matsuyama Hidetoshi
Research Institute of Biological Resources, National Institute of Advanced Industrial Science and Technology, 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, 062-8517, Japan.
Arch Microbiol. 2004 May;181(5):345-51. doi: 10.1007/s00203-004-0662-8. Epub 2004 Apr 6.
A facultative psychrophilic bacterium, strain L-2, that grows at 0 and 5 degrees C as minimum growth temperatures in complex and defined media, respectively, was isolated. On the basis of taxonomic studies, strain L-2 was identified as Cobetia marina. The adaptability of strain L-2 to cold temperature was higher than that of the type strain and of other reported strains of the same species. When the bacterium was grown at 5-15 degrees C in a defined medium, it produced a high amount of trans-unsaturated fatty acids. By contrast, in a complex medium in the same temperature range it produced a low amount of trans-unsaturated fatty acids. In the complex medium at 5 degrees C, the bacterium exhibited a three-fold higher growth rate than that obtained in the defined medium. Following a temperature shift from 11 to 5 degrees C, strain L-2 grew better in complex than in defined medium. Furthermore, when the growth temperature was shifted from 0 to 5 degrees C both the growth rate and the yield of strain L-2 growing in complex medium was markedly enhanced. These phenomena suggest that an upshift of the growth temperature had a positive effect on metabolism. The effects of adding complex medium components to the defined medium on bacterial growth rate and fatty acid composition at 5 degrees C were also studied. The addition of yeast extract followed by peptone was effective in promoting rapid growth, while glutamate addition was less effective, resulting in a cis-unsaturated fatty acid ratio similar to that of cells grown in the complex medium. These results suggest that the rapid growth of strain L-2 at low temperatures requires a high content of various amino acids rather than the presence of a high ratio of cis-unsaturated fatty acids in the cell membrane.
分离出了一种兼性嗜冷细菌L-2菌株，该菌株在复合培养基和限定培养基中的最低生长温度分别为0℃和5℃。基于分类学研究，L-2菌株被鉴定为海科贝氏菌。L-2菌株对低温的适应性高于模式菌株和其他已报道的同物种菌株。当该细菌在限定培养基中于5-15℃培养时，会产生大量反式不饱和脂肪酸。相比之下，在相同温度范围内的复合培养基中，它产生的反式不饱和脂肪酸量较低。在5℃的复合培养基中，该细菌的生长速率比在限定培养基中高三倍。从11℃转移到5℃后，L-2菌株在复合培养基中的生长比在限定培养基中更好。此外，当生长温度从0℃转移到5℃时，L-2菌株在复合培养基中的生长速率和产量均显著提高。这些现象表明生长温度的升高对代谢有积极影响。还研究了在限定培养基中添加复合培养基成分对5℃时细菌生长速率和脂肪酸组成的影响。添加酵母提取物后再添加蛋白胨可有效促进快速生长，而添加谷氨酸的效果较差，导致顺式不饱和脂肪酸比例与在复合培养基中生长的细胞相似。这些结果表明，L-2菌株在低温下的快速生长需要高含量的各种氨基酸，而不是细胞膜中高比例的顺式不饱和脂肪酸。
