【摘要】 目的研究广西茅尾海红树林植物根际土壤放线菌资源多样性及抗菌活性,为寻找新型抗菌药物奠定基础。方法采集自茅尾海的红树林土壤样品8份,采用8种分离培养基,以稀释涂布法分离纯化放线菌;通过PCR扩增和测序获得菌株16SrRNA基因序列并在数据库中搜索比对,分析放线菌抗菌活性的多样性;放线菌液发酵后离心,留取上清液,部分用乙酸乙酯萃取,菌丝经丙酮浸泡萃取。分别取发酵液水相、酯相、菌丝浸提液3类样品;采用纸片扩散法(KB法)测定其抗菌活性;对4株活性菌进行形态学和生理生化检测。结果从8份红树林根际土壤标本中共分离到88株放线菌,分属于6个目8个科9个属,优势菌属为小单孢菌属和链霉菌属;桐花树根际土壤样品和高氏一号培养基分离的菌株较多;16SrRNA基因序列相似率低于98.65%的放线菌共6株;抗菌活性检测结果表明,14株放线菌中,有7株具良好抗菌活性,阳性率为50.00%,其中4株分别对粪肠球菌或表皮球菌有一定抑制效果。初步鉴定B44为链霉菌属Streptomyces aurantiogriseua NBRC12842,相似率为99.43%;B534为小双孢菌属Micromonospora bryophytorumNEAU-TX2-2,相似率为99.86%;B593和B276为壤霉菌属Agromyces aurantiacusYIM21741,相似率分别为98.29%和98.32%,其相似率低于98.65%可能为潜在新物种。结论广西茅尾海红树林植物根际土壤中含有丰富的放线菌资源,具有从中发现放线菌新型物种和新抗生素的潜力。更多还原

【Abstract】 Objectives To study the diversity and antimicrobial activity of actinobacteria isolated from mangrove rhizosphere soil in the Maowei Sea Mangrove Reserve,Guangxi Zhuang Autonomous Region and to lay the foundation for finding new antibacterials. Methods Eight rhizosphere soil samples were collected from the Maowei Sea Mangrove Reserve.Actinobacteria were isolated using the standard serial dilution plating technique with eight different media.To analyze the diversity of actinobacteria,sequences of the 16 SrRNA gene obtained by amplification with PCR were submitted to a gene database for a BLAST search.The fermentation broths and mycelia of the actinobacterial strains were respectively extracted using ethyl acetate and acetone.Three different samples were obtained,including the organic layer,water layer,and acetone extract.The disk diffusion method was used to test for antimicrobial activity.Morphological and biochemical tests were performed on 4 active strains. Results A total of 88 actinobacteria strains,belonging to 9 genera in8 families in 6 orders,were isolated and purified from eight mangrove rhizosphere soil samples.Micromonospora and Streptomyces were dominant genera.More strains were isolated from soil samples in the rhizosphere of Aegiceras corniculatumand Gause’s Synthetic medium.The similarity of the 16 SrRNA gene sequence in 6 strains and related species was less than 98.65%.An antimicrobial assay revealed that 7 out of 14 strains(50.00%)tested positive for antibacterial or antifungal activity.Four strains inhibited Enterococcus faecalis and Staphylococcus epidermidis to an extent.The simi-larity of the 16 SrRNA gene sequence in strain B44 and the validly described species Streptomyces aurantiogriseum NBRC12842 was 99.43%,and the similarity of that sequence in strain B534 and Microbispora bryophytorum NEAUTX2-2 was 99.86%.The similarity of the 16 SrRNA gene sequence in strain B593 and the validly described species Agromyces aurantiacus YIM21741 was 98.29%,and the similarity of that sequence in strain B276 was 98.32%.Less similarity(< 98.65%)between B593 and B276 and Agromyces aurantiacus YIM21741 indicated that the two strains were potential new taxa. Conclusion This study demonstrated that actinobacteria from the Maowei Sea Mangrove Reserve were high diverse and thus deserve to be examined further to discover new actinobacteria taxa and antibiotics.更多还原