Nagata Shinichi, Wang Chenxiang
Environmental Biochemistry Group, Research Center for Inland Seas, Kobe University, 5-1-1 Fukae, Higashinada-ku, Kobe 658-0022, Japan.
J Biosci Bioeng. 2005 Jan;99(1):61-7. doi: 10.1263/jbb.99.61.
Halophilic and non-halophilic bacteria subjected to osmotic downshock, from 0.7 M NaCl to deionized water, were examined for their survival, with the uptake and utilization of the cyclic amino acid ectoine, one of the representative compatible solutes, being taken into account. The uptake of ectoine added externally and survival of the cells were monitored as a function of incubation time in the presence and absence of NaCl. The halophilic Brevibacterium sp. JCM 6894 and B. epidermidis JCM 2593 actively accumulated ectoine regardless of the presence of NaCl, which led to cell survival. Brevibacterium casei JCM 2594 belonging to the same Brevibacterium species, however, revealed Na+-dependence of its uptake activity of ectoine. Non-halophilic Escherichia coli K-12 did not accumulate ectoine, and thereby this strain failed to survive irrespective of whether NaCl was present. The physiological meanings of the downshock procedure are discussed in connection with the uptake and the subsequent utilization of ectoine.
研究了嗜盐菌和非嗜盐菌在渗透压从0.7M氯化钠降至去离子水的情况下的存活情况，并考虑了环状氨基酸依克多因（一种代表性的相容性溶质）的摄取和利用。在有和没有氯化钠的情况下，监测外部添加的依克多因的摄取以及细胞的存活情况，并将其作为孵育时间的函数。嗜盐的短杆菌属JCM 6894和表皮短杆菌JCM 2593无论有无氯化钠都会主动积累依克多因，这导致细胞存活。然而，属于同一短杆菌属的干酪短杆菌JCM 2594显示出其依克多因摄取活性对钠离子的依赖性。非嗜盐的大肠杆菌K-12不积累依克多因，因此无论有无氯化钠，该菌株都无法存活。结合依克多因的摄取和随后的利用，讨论了渗透压降低过程的生理意义。
