中文摘要：

以湛江南海海域常见的10种海洋动物为研究对象，采用倾注平板法分离肠道乳酸菌，以单核细胞增生李斯特氏菌（Listeriamonocytogenes）等5株有害菌为指示菌，采用双层牛津杯扩散法测定其抗菌活性，通过建立16SrRNA基因序列的系统发育树对具有抗菌活性的乳酸菌进行多样性分析。结果表明：根据形态观察和部分生理生化实验去重复后，共分离出43株有溶钙圈、革兰氏染色呈阳性、过氧化氢酶反应为阴性的乳酸菌，并且均不同程度地具有抗菌活性。对其中的13株抗菌能力强、抗菌谱广的乳酸菌进行16SrRNA分子生物学鉴定与分析，发现它们分属于厚壁菌门（Firmicutes）的4个科6个属，且除菌株LY-87与模式菌株Lactococcuslactissubsp.lactis的16SrRNA基因序列相似性为100%外，其他菌株与其系统发育关系最密切的典型菌株之间都存在着一定的遗传差异（相似性为95.7%～99.9%），其中菌株PQ-26与模式菌株Pediococcuspentosaceus的相似性仅为95.7%，可能是Pediococcus属中潜在的新种。研究表明湛江南海海域动物肠道中存在较为丰富的抗菌活性乳酸菌，并可能蕴藏着乳酸菌新种，其抗菌物质资源有待进一步研究与开发。

英文摘要：

Lactic acid bacteria(LAB)were isolated from the intestine of10common kinds of marine animals collected from the South China Sea by the pour plate method.The antimicrobial activity of the LAB isolates was determined by Oxford cup diffusion method against five pathogenic indicator strains including E.coli,V.parahaemolytics,S.aureus,B.subtilis,and L.monocytogenes.The diversity analysis of these LAB strains was conducted by establishing phylogenetic tree based on16S rRNA gene sequences.The results showed that43isolates,which presented soluble calcium circle and were positive by Gram staining and negative in catalase reaction,were identified as LAB according to morphological observation and partial physiological and biochemical experiments,and they all possessed antimicrobial activity in different degrees.Out of these,13strains were found to have stronger bacteriostatic ability and a wider antimicrobial spectrum,and they were further identified based on phyogenetical analysis of16S rRNA sequence.The results indicated that they belonged to6genera in4families of Firmicutes.Although strain LY-87and the type strain of Lactococcus lactis subsp.lactis shared100%16S rRNA gene sequence similarity,there were genetic differences between other LAB strains and the typical strains showing the closest phylogenetic relationship with them(similarity ranging from95.7%to99.9%).The similarity between strain PQ-26and the type strain of Pediococcus pentosaceus was only95.7%suggesting that it is likely to be a potential new species of Pediococcus.This research indicates that LAB with antimicrobial activity are diverse and there may exist potential new species in the intestine of animals from the South China Sea in Zhanjiang.The antimicrobial substances produced by these bacteria need to be further studied and developed.