School of Basic Courses, Guangdong Pharmaceutical University, Guangzhou, 510006, P. R. China.
Guangdong Key Laboratory of Pharmaceutical Bioactive Substances, Guangdong Pharmaceutical University, Guangzhou, 510006, P. R. China.
J Microbiol. 2018 Jul;56(7):516-523. doi: 10.1007/s12275-018-7510-z. Epub 2018 Jun 28.
Actinomycetes are well-known for producing numerous bioactive secondary metabolites. In this study, primary screening by antifungal activity assay found one actinomycete strain WA23-4-4 isolated from the intestinal tract of Periplaneta americana that exhibited broad spectrum antifungal activity. 16S rDNA gene analysis of strain WA23-4-4 revealed close similarity to Streptomyces nogalater (AB045886) with 86.6% sequence similarity. Strain WA23-4-4 was considered as a novel Streptomyces and the 16s rDNA sequence has been submitted to GenBank (accession no. KX291006). The maximum antifungal activity of WA23-4-4 was achieved when culture conditions were optimized to pH 8.0, with 12% inoculum concentration and 210 ml ISP2 medium, which remained stable between the 5 and the 9 day. 3-Acetyl benzoyl amide was isolated by ethyl acetate extraction of WA23-4-4 fermentation broth, and its molecular formula was determined as CHNO based on MS, IR, H, and C NMR analyses. The compound showed significant antifungal activity against Candida albicans ATCC 10231 (MIC: 31.25 μg/ml) and Aspergillus niger ATCC 16404 (MIC: 31.25 μg/ml). However, the compound had higher MIC values against Trichophyton rubrum ATCC 60836 (MIC: 500 μg/ml) and Aspergillus fumigatus ATCC 96918 (MIC: 1,000 μg/ml). SEM analysis showed damage to the cell membrane of Candida albicans ATCC 10231 and to the mycelium of Aspergillus niger ATCC 16404 after being treatment with 3-acetyl benzoyl amide. In conclusion, this is the first time that 3-acetyl benzoyl amide has been identified from an actinomycete and this compound exhibited antifungal activity against Candida albicans ATCC 10231 and Aspergillus niger ATCC 16404.
放线菌以产生多种生物活性次级代谢产物而闻名。在本研究中，通过抗真菌活性测定的初步筛选，从美洲大蠊肠道中分离到一株放线菌 WA23-4-4，该菌表现出广谱抗真菌活性。WA23-4-4 菌株的 16S rDNA 基因分析显示与链霉菌（AB045886）具有 86.6%的序列相似性。WA23-4-4 菌株被认为是一种新型链霉菌，其 16s rDNA 序列已提交给 GenBank（登录号 KX291006）。当优化培养条件至 pH 8.0、接种浓度为 12%、使用 210ml ISP2 培养基时，WA23-4-4 的最大抗真菌活性得以实现，并且在第 5 天至第 9 天之间保持稳定。通过 WA23-4-4 发酵液的乙酸乙酯萃取，分离出 3-乙酰苯甲酰胺，根据 MS、IR、H 和 C NMR 分析确定其分子式为 CHNO。该化合物对白色念珠菌 ATCC 10231（MIC：31.25μg/ml）和黑曲霉 ATCC 16404（MIC：31.25μg/ml）具有显著的抗真菌活性。然而，该化合物对红色毛癣菌 ATCC 60836（MIC：500μg/ml）和烟曲霉 ATCC 96918（MIC：1000μg/ml）的 MIC 值更高。SEM 分析显示，3-乙酰苯甲酰胺处理后，白色念珠菌 ATCC 10231 的细胞膜和黑曲霉 ATCC 16404 的菌丝受到损伤。总之，这是首次从放线菌中鉴定出 3-乙酰苯甲酰胺，该化合物对白色念珠菌 ATCC 10231 和黑曲霉 ATCC 16404 表现出抗真菌活性。
