Malaria Drug Discovery Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, 110067, India.
Microbial Biotechnology Laboratory, Life Sciences Division, Institute of Advanced Study in Science and Technology (IASST), An Autonomous Institute under Department of Science and Technology (Govt. of India), Paschim Boragaon, Garchuk, Guwahati, 781035, Assam, India.
Sci Rep. 2020 Mar 5;10(1):4104. doi: 10.1038/s41598-020-60968-6.
Actinobacteria is a goldmine for the discovery of abundant secondary metabolites with diverse biological activities. This study explores antimicrobial biosynthetic potential and diversity of actinobacteria from Pobitora Wildlife Sanctuary and Kaziranga National Park of Assam, India, lying in the Indo-Burma mega-biodiversity hotspot. A total of 107 actinobacteria were isolated, of which 77 exhibited significant antagonistic activity. 24 isolates tested positive for at least one of the polyketide synthase type I, polyketide synthase type II or non-ribosomal peptide synthase genes within their genome. Their secondary metabolite pathway products were predicted to be involved in the production of ansamycin, benzoisochromanequinone, streptogramin using DoBISCUIT database. Molecular identification indicated that these actinobacteria predominantly belonged to genus Streptomyces, followed by Nocardia and Kribbella. 4 strains, viz. Streptomyces sp. PB-79 (GenBank accession no. KU901725; 1313 bp), Streptomyces sp. Kz-28 (GenBank accession no. KY000534; 1378 bp), Streptomyces sp. Kz-32 (GenBank accession no. KY000536; 1377 bp) and Streptomyces sp. Kz-67 (GenBank accession no. KY000540; 1383 bp) showed ~89.5% similarity to the nearest type strain in EzTaxon database and may be considered novel. Streptomyces sp. Kz-24 (GenBank accession no. KY000533; 1367 bp) showed only 96.2% sequence similarity to S. malaysiensis and exhibited minimum inhibitory concentration of 0.024 µg/mL against methicilin resistant Staphylococcus aureus ATCC 43300 and Candida albicans MTCC 227. This study establishes that actinobacteria isolated from the poorly explored Indo-Burma mega-biodiversity hotspot may be an extremely rich reservoir for production of biologically active compounds for human welfare.
放线菌是发现具有丰富生物活性的次生代谢产物的宝库。本研究探索了来自印度阿萨姆邦波比托拉野生动物保护区和卡齐兰加国家公园的放线菌的抗菌生物合成潜力和多样性，该地区位于印度-缅甸生物多样性热点地区。共分离出 107 株放线菌，其中 77 株表现出显著的拮抗活性。24 株放线菌的基因组中至少检测到一个聚酮合酶 I 型、聚酮合酶 II 型或非核糖体肽合酶基因呈阳性。利用 DoBISCUIT 数据库预测，它们的次生代谢途径产物涉及安莎霉素、苯并异色满醌、链阳性菌素的产生。分子鉴定表明，这些放线菌主要属于链霉菌属，其次是诺卡氏菌属和克里贝拉属。有 4 株菌株，即 PB-79 链霉菌（GenBank 登录号 KU901725；1313bp）、Kz-28 链霉菌（GenBank 登录号 KY000534；1378bp）、Kz-32 链霉菌（GenBank 登录号 KY000536；1377bp）和 Kz-67 链霉菌（GenBank 登录号 KY000540；1383bp）与 EzTaxon 数据库中最接近的模式菌株相似度约为 89.5%，可能是新种。Kz-24 链霉菌（GenBank 登录号 KY000533；1367bp）与 S. malaysiensis 的序列相似度仅为 96.2%，对耐甲氧西林金黄色葡萄球菌 ATCC 43300 和白色念珠菌 MTCC 227 的最小抑菌浓度为 0.024μg/mL。本研究表明，从探索较少的印度-缅甸生物多样性热点地区分离出的放线菌可能是产生有益于人类健康的生物活性化合物的极其丰富的资源库。
