南极适冷菌Pseudoaltermonas sp. S-15-13胞外多糖低温保护作用的研究

Study on Cryoprotection of Exopolysaccharides From Antarctic Psychrotroph Pseudoaltermonas sp. S-15-13

研究了南极适冷菌Pseudoaltermonas sp.S-15-13胞外多糖(Exopolysaccharides,EPSs)对重复冻融的菌体的保护作用。结果表明,重复冻融循环后,有胞外多糖包被的菌体仍能保持较好的生长能力,无胞外多糖包被的菌体生长缓慢,甚至死亡;不同浓度的胞外多糖均可降低水溶液的冰点,其效果较浓度相同的葡聚糖明显。说明南极适冷菌S-15-13对反复冻融的耐受能力与菌体分泌的胞外多糖直接相关,除了形成机械隔离屏障,胞外多糖还可能通过降低冰点等途径使菌体免受伤害。

In this paper, the cryoprotection of exopolysaccharides （EPSs） from Antarctic psychrotroph Pseudoalterrnonas sp. S-15-13 is studied. It is shown from the study results that after repeated freeze-thaw cycles, the psychrotrophs S-15-13 enwrapped with EPSs still kept better growth ability, but those enwrapped without EPSs grew slowly and even died; different concentrations of EPSs could lower the freezing point of wter solution, and their lowering effects were more significant than those of glucans with the same concentrations, which indicates that the ability of Antarctic psychrotroph to withstand the freezethaw cycles is related directly to its sectreted EPSs. Besides forming a mechanically isolation barrier, EPSs might prevent the psychrotroph S-15-13 from damaging by lowering the freezing point of water solution.