Li Yan, Wu Chaoya, Zhou Mingyang, Wang En Tao, Zhang Zhenpeng, Liu Wei, Ning Jicai, Xie Zhihong
Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences Yantai, China.
Key Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of SciencesYantai, China; School of Chemical and Biological Engineering, Lanzhou Jiaotong UniversityLanzhou, China.
Front Microbiol. 2017 Mar 16;8:405. doi: 10.3389/fmicb.2017.00405. eCollection 2017.
Protease-producing bacteria are widespread in ocean sediments and play important roles in degrading sedimentary nitrogenous organic materials. However, the diversity of the bacteria and the proteases involved in such processes remain largely unknown especially for communities in enclosed sea bays. Here, we investigated the diversity of the extracellular protease-producing bacteria and their protease types in Laizhou Bay. A total of 121 bacterial isolates were obtained from sediment samples in 7 sites and their protease types were characterized. The abundance of cultivable protease-producing bacteria was about 10 CFU g of sediment. Phylogenetic analysis based on 16S rRNA gene sequences suggest that the isolates belonged to 17 genera from 4 phyla including and , and mainly dominated by the genera (40.5%), (36.3%), and (5.8%). The diversity and community structure varied among different sampling sites but no significant correlation was observed with soil sediment's characteristics. Enzyme activity and inhibition tests further revealed that all isolates secreted proteases that were inhibited by serine and/or metalloprotease inhibitors, and a smaller proportion was inhibited by inhibitors of cysteine and/or aspartic proteases. Furthermore, all isolates effectively degraded casein and/or gelatin with only a few that could hydrolyze elastin, suggesting that the bacteria were producing different kinds of serine proteases or metalloproteases. This study provided novel insights on the community structure of cultivable protease-producing bacteria near the Yellow River estuary of an enclosed sea bay.
产蛋白酶细菌广泛存在于海洋沉积物中，在降解沉积性含氮有机物质方面发挥着重要作用。然而，参与此类过程的细菌和蛋白酶的多样性在很大程度上仍不清楚，尤其是对于封闭海湾中的群落而言。在此，我们调查了莱州湾产细胞外蛋白酶细菌的多样性及其蛋白酶类型。从7个位点的沉积物样本中总共获得了121株细菌分离株，并对它们的蛋白酶类型进行了表征。可培养的产蛋白酶细菌的丰度约为每克沉积物10 CFU。基于16S rRNA基因序列的系统发育分析表明，这些分离株属于4个门的17个属，包括 和 ，主要以 属（40.5%）、 属（36.3%）和 属（5.8%）为主。不同采样位点的多样性和群落结构有所不同，但与土壤沉积物特征未观察到显著相关性。酶活性和抑制试验进一步表明，所有分离株分泌的蛋白酶均被丝氨酸和/或金属蛋白酶抑制剂抑制，较小比例被半胱氨酸和/或天冬氨酸蛋白酶抑制剂抑制。此外，所有分离株均能有效降解酪蛋白和/或明胶，只有少数能水解弹性蛋白，这表明这些细菌产生了不同种类的丝氨酸蛋白酶或金属蛋白酶。本研究为封闭海湾黄河口附近可培养产蛋白酶细菌的群落结构提供了新的见解。
