Abstract: Over long periods of evolution, Antarctic sea-ice microorganisms obtained special physiological and biochemical characterristics and gene expression regulation mechanisms to adapt extreme environment. To learn more about the adaption mechanism of the Antarctic microorganisms, the strains growth, total protein content, permeability of cell membrane, malondialdehyde and antioxidant enzymes system activity including SOD, POD and CAT had been studied under different salinity conditions of 3%~9% based on the Pseudoalteromonas sp. ANT319, which belongs to the typical genus in Antarctic bacteria. The results showed that the optimum salinity for P. sp. ANT319 was 9%. With salinity increasing, the total protein content and membrane permeability increased while SOD and POD enzymatic activities presented a trend of increasing firstly with the highest at 9% and then decreasing later, meanwhile CAT activity and MDA kept steady. Therefore, as the salinity increased, total proteins content increased as  result of cell membranes damaged gradually, meanwhile, the strain produced more proteins to remove harmful reactive oxygen species caused by salt stress and the activities of antioxidant enzymes were also enhanced. These results revealed the salinity tolerance mechanism of sea-ice bacteria preliminarily.

Key words: Antarctic;Pseudoalteromonas sp. ANT319, salt tolerance, sea-ice

摘要： 南极海冰微生物在适应极端环境的长期进化过程中，获得了特殊的生理生化特性和基因表达调控机制。为了更多的了解南极微生物的逆境适应机制，以隶属南极海冰微生物典型菌属Pseudoalteromonas的ANT319为研究对象，探讨了该菌株在3%~12%的盐度梯度下的抗盐生长情况、蛋白质含量变化、细胞膜透性、丙二醛含量变化和不同盐度对菌株细胞内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)3种抗氧化酶活性的影响。结果表明，此菌株的最适生长盐度为9%，随着盐度的升高，细胞内蛋白质含量升高，膜透性逐渐增加，SOD和POD的酶活性呈现先升高后降低的变化趋势，在9%盐度下达到最高，CAT活性和MDA则基本上保持不变。可见，随着盐度的增加，细胞膜逐渐受到破坏，同时生物体对盐迫作出应激反应，产生较多蛋白来清除不良因素下产生的有害活性氧，包括生物体内抗氧化酶在内的蛋白含量及其活性的增加，研究结果初步揭示了海冰细菌的耐盐机制。

关键词: 南极, Pseudoalteromonas sp. ANT319, 耐盐性, 海冰