Su Hongfei, Xiao Zhenlun, Yu Kefu, Huang Qinyu, Wang Guanghua, Wang Yinghui, Liang Jiayuan, Huang Wen, Huang Xueyong, Wei Fen, Chen Biao
Coral Reef Research Center of China, Guangxi University, Nanning, Guangxi, China.
Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Guangxi University, Nanning, Guangxi, China.
PeerJ. 2020 May 6;8:e9055. doi: 10.7717/peerj.9055. eCollection 2020.
Protease-producing bacteria play a vital role in degrading organic nitrogen in marine environments. However, the diversity of the bacteria and extracellular proteases has seldom been addressed, especially in communities of coral reefs. In this study, 136 extracellular protease-producing bacterial strains were isolated from seven genera of scleractinian corals from Luhuitou fringing reef, and their protease types were characterized. The massive coral had more cultivable protease-producing bacteria than branching or foliose corals. The abundance of cultivable protease-producing bacteria reached 10 CFU g of coral. Phylogenetic analysis of 16S rRNA gene sequences revealed that the isolates were assigned to 24 genera, from which 20 corresponded to the phyla and and were retrieved from all coral samples. Moreover, and were most prevalent in massive or foliose coral and In contrast, 11 genera were each identified in only one isolate. Nearly all the extracellular proteases from the bacteria were serine proteases or metalloproteases; 45.83% of isolates also released cysteine or aspartic proteases. These proteases had different hydrolytic ability against different substrates. This study represents a novel insight on the diversity of cultivable protease-producing bacteria and their extracellular proteases in scleractinian corals.
产蛋白酶细菌在海洋环境中有机氮的降解过程中发挥着至关重要的作用。然而，这类细菌及其胞外蛋白酶的多样性却很少得到研究，尤其是在珊瑚礁群落中。在本研究中，从鹿回头岸礁的7个石珊瑚属中分离出136株产胞外蛋白酶的细菌菌株，并对它们的蛋白酶类型进行了表征。块状珊瑚比分支状或叶状珊瑚拥有更多可培养的产蛋白酶细菌。可培养的产蛋白酶细菌丰度达到每克珊瑚10 CFU。基于16S rRNA基因序列的系统发育分析表明，分离菌株被归为24个属，其中20个属对应于各个门，且所有珊瑚样本中均检测到了这些门。此外，[具体属名1]和[具体属名2]在块状或叶状珊瑚中最为普遍，相比之下，11个属仅在一个分离菌株中被鉴定到。几乎所有细菌产生的胞外蛋白酶均为丝氨酸蛋白酶或金属蛋白酶；45.83%的分离菌株还能分泌半胱氨酸蛋白酶或天冬氨酸蛋白酶。这些蛋白酶对不同底物具有不同的水解能力。本研究为石珊瑚中可培养的产蛋白酶细菌及其胞外蛋白酶的多样性提供了新的见解。
