关键词: 美洲大蠊, 粪便, 真菌, 放线菌, 抗菌活性, 分子鉴定, 系统发育

Abstract: 【Aim】 To investigate the fungi and actinomycetes with antimicrobial activity in Periplaneta americana frass, so as to supply microbial sources for the development of antimicrobial medications. 【Methods】 Using the dilution coating method and selective culture method, actinomycetes and fungi were isolated and purified from the frass of adult P. americana collected from the P. americana farm in Weishan County, Dali Bai Autonomous Prefecture, Yunnan Province, China. The antibacterial activities of metabolites of these strains against six pathogenic bacteria Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, methicillin-resistant S. aureus, Pseudomonas aeruginosa and Salmonella typhimurium were detected by the Oxford cup agar diffusion method. The strains with antibacterial activity were identified by the 16S rDNA gene sequencing and ITS rDNA gene sequencing, and a phylogenetic tree of the strains with antibacterial activities was constructed using the neighbor-joining method. 【Results】 Seventeen strains of fungi and 19 strains of actinomycetes were isolated from the frass of adult P. americana. Six strains of fungi and 12 strains of actinomycetes exhibited varying degrees of antibacterial activity. Among them, the fungi EPAF15-EPAF17 and the actinomycetes EPAA12 and EPAA17 showed broad-spectrum antibacterial activities against E. coli, S. aureus, methicillin-resistant S. aureus, P. aeruginosa and S. typhimurium. Phylogenetic analysis showed that the fungi with antibacterial activity belong to Fusarium, Hyphopichia and Trichosporon, and the actinomycetes with antibacterial activity belong to the genus Streptomyces. 【Conclusion】 There are various types of culturable microorganisms in the frass of adult P. americana. The discovery of fungi and actinomycetes with antibacterial activity provides essential microbial resources for further exploration of new antimicrobial natural drugs. It also introduces a new concept for fully utilizing microbial resources in a special environment.

Key words: Periplaneta americana, frass, fungi, actinomyces, antibacterial activity, molecular identification, phylogeny