BACKGROUND Psychrophiles have evolved themselves to adapt to freezing environment, and cold-adapted enzymes from these organisms can maintain high catalytic activity at low temperature. The use of cold-adapted enzymes have great potential for the revolution of food and molecular biology industries. RESULTS In this study, 4 different strains producing protease were isolated from traditional fermented shrimp paste, one of which, named as Planococcus maritimus XJ11 by 16S rRNA nucleotide sequence analysis, exhibited the largest protein hydrolysis clear zone surrounding the colonies. Meanwhile, the strain P. maritimus XJ11 was selected for further investigation because of its great adaption to low temperature, low salinity and alkaline environment. The enzyme activity assay of P. maritimus XJ11 indicated that the optimum conditions for catalytic activity were pH 10.0 and 40 °C. Moreover, the enzyme also showed an increasing activity with temperatures from 10 to 40 °C and retained more than 67% activity of the maximum over a broad range of salinity (50 ~ 150 g/L). Genome sequencing analysis revealed that the strain XJ11 owned one circular chromosome of 3,282,604 bp and one circular plasmid of 67,339 bp with a total number of 3,293 open reading frames (ORFs). Besides, 21 genes encoding protease, including three serine proteases, were identified through NR database. CONCLUSION Cold-adapted bacterium P. maritimus XJ11 was capable of producing alkaline proteases with high catalytic efficiency at low or moderate temperatures. Furthermore, the favorable psychrophilic and enzymatic characters of strain P. maritimus XJ11 seem to have a promising potential for industrial application. This article is protected by copyright. All rights reserved.

中文翻译：

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从传统虾酱中分离出的冷适应蓝藻的基因组测序及蛋白酶鉴定

背景技术嗜冷菌自身已经进化以适应冰冻环境，来自这些生物的冷适应酶可以在低温下保持高催化活性。冷适应酶的使用对于食品和分子生物学行业的革命具有巨大的潜力。结果本研究从传统的发酵虾酱中分离出4株不同的产蛋白酶菌株，其中1株经16S rRNA核苷酸序列分析命名为Planococcus maritimus XJ11，在菌落周围表现出最大的蛋白质水解透明区。同时，选择P. maritimus XJ11菌株对低温、低盐度和碱性环境的适应性强，进行进一步研究。P.酶活性测定 maritimus XJ11 表明催化活性的最佳条件是 pH 10.0 和 40 °C。此外，该酶还显示出随着温度从 10 到 40 °C 增加的活性，并且在很宽的盐度范围（50 ~ 150 g/L）内保持了超过 67% 的最大值。基因组测序分析显示，菌株XJ11拥有一条3,282,604 bp的环状染色体和一条67,339 bp的环状质粒，共有3,293个开放阅读框（ORFs）。此外，通过NR数据库鉴定了21个蛋白酶编码基因，包括3个丝氨酸蛋白酶。结论冷适应细菌P. maritimus XJ11能够在低温或中温下产生具有高催化效率的碱性蛋白酶。此外，菌株 P 良好的嗜冷和酶促特性。maritimus XJ11 似乎有很大的工业应用潜力。本文受版权保护。版权所有。