裂解褐藻胶海洋微生物的分离筛选及其功能基因进化分析

Isolation,Screening and Functional Gene Evolution Analysis of Alginate Lysing Marine Microorganisms

本研究以褐藻酸钠为唯一碳源,从广西茅尾海采集的海藻和海水样品中分离获得了10株高产褐藻胶裂解酶(Alginate lyase)的菌株,经过16S rDNA系统发育分析,初步确定这些菌株分别属于盐单胞菌属、假交替单胞菌属和弧菌属。为进一步了解褐藻胶裂解酶(ALG)功能基因的进化轨迹,本研究从GenBank收集了alg基因的同源序列。通过系统发育分析和极大似然分析,运行位点模型和分支位点模型进行了计算,确定该基因存在正选择现象。正选择进化分析结果表明4Y、16I、40N、61L、91T、99S、149L和154S为alg基因的正选择位点,提示环境选择压力促进了alg基因的进化。本研究为后续褐藻胶裂解酶定向诱变或残基的结构与功能之间的作用机制等相关研究提供重要的科学依据和理论支撑。

This study used sodium alginate as sole carbon source.Ten high-yielding alginate lyase strains were isolated from algae and seawater samples from Maowei Sea in Guangxi.After 16S rDNA phylogenetic analysis,the strains were classified into the genus Halomonas,Pseudoalmonas and Vibrio,respectively.To further explore the evolutionary history of alginate lyase(ALG),the study collected homologous sequences of the alg gene from GenBank.The potential positive selection site of the alg gene was confirmed by phylogenetic analysis,maximum likelihood analysis,using a site model and a branch site model.Positive selection evolution analysis results showed that 4Y,16I,40N,61L,91T,99S,149L,and 154S were the positive selection sites of the alg gene,which indicated that forward environmental pressures may promote the evolution of the alg gene.This study provided an important scientific basis and theoretical support for subsequent related researches such as directed mutagenesis or the structure and function modification of the alg enzyme.