Passari Ajit K, Mishra Vineet K, Saikia Ratul, Gupta Vijai K, Singh Bhim P
Molecular Microbiology and Systematics Laboratory, Department of Biotechnology, Mizoram University Aizawl, India.
Biotechnology Division, CSIR-North East Institute of Science and Technology Jorhat, Assam, India.
Front Microbiol. 2015 Apr 7;6:273. doi: 10.3389/fmicb.2015.00273. eCollection 2015.
Microorganisms associated with medicinal plants are of interest as the producers of important bioactive compounds. To date, the diversity of culturable endophytic actinomycetes associated with medicinal plants is in its initial phase of exploration. In this study, 42 endophytic actinomycetes were isolated from different organs of seven selected medicinal plants. The highest number of isolates (n = 22, 52.3%) of actinomycetes was isolated from roots, followed by stems (n = 9, 21.4%), leaves (n = 6, 14.2%), flowers (n = 3, 7.1%), and petioles (n = 2, 4.7%). The genus Streptomyces was the most dominant among the isolates (66.6%) in both the locations (Dampa TRF and Phawngpuii NP, Mizoram, India). From a total of 42 isolates, 22 isolates were selected for further studies based on their ability to inhibit one of the tested human bacterial or fungal pathogen. Selected isolates were identified based on 16S rRNA gene analysis and subsequently the isolates were grouped to four different genera; Streptomyces, Brevibacterium, Microbacterium, and Leifsonia. Antibiotic sensitivity assay was performed to understand the responsible antimicrobials present in the isolates showing the antimicrobial activities and revealed that the isolates were mostly resistant to penicillin G and ampicillin. Further, antimicrobial properties and antibiotic sensitivity assay in combination with the results of amplification of biosynthetic genes polyketide synthase (PKS-I) and non-ribosomal peptide synthetase (NRPS) showed that the endophytic actinomycetes associated with the selected medicinal plants have broad-spectrum antimicrobial activity. This is the first report of the isolation of Brevibacterium sp., Microbacterium sp., and Leifsonia xyli from endophytic environments of medicinal plants, Mirabilis jalapa and Clerodendrum colebrookianum. Our results emphasize that endophytic actinomycetes associated with medicinal plants are an unexplored resource for the discovery of biologically active compounds.
与药用植物相关的微生物作为重要生物活性化合物的生产者备受关注。迄今为止,与药用植物相关的可培养内生放线菌的多样性仍处于探索的初始阶段。在本研究中,从七种选定药用植物的不同器官中分离出42株内生放线菌。放线菌分离株数量最多的是根(n = 22,52.3%),其次是茎(n = 9,21.4%)、叶(n = 6,14.2%)、花(n = 3,7.1%)和叶柄(n = 2,4.7%)。在两个地点(印度米佐拉姆邦的丹帕老虎保护区和法翁普伊国家公园),链霉菌属在分离株中占主导地位(66.6%)。从总共42株分离株中,基于其抑制一种受试人类细菌或真菌病原体的能力,选择了22株进行进一步研究。根据16S rRNA基因分析对选定的分离株进行鉴定,随后将这些分离株分为四个不同的属:链霉菌属、短杆菌属、微杆菌属和利夫松菌属。进行了抗生素敏感性试验,以了解显示抗菌活性的分离株中存在的负责抗菌物质,结果表明这些分离株大多对青霉素G和氨苄青霉素耐药。此外,抗菌特性和抗生素敏感性试验结合聚酮合酶(PKS-I)和非核糖体肽合成酶(NRPS)生物合成基因扩增结果表明,与选定药用植物相关的内生放线菌具有广谱抗菌活性。这是首次从药用植物紫茉莉和臭牡丹的内生环境中分离出短杆菌属、微杆菌属和木糖利夫松菌的报道。我们的结果强调,与药用植物相关的内生放线菌是发现生物活性化合物的未开发资源。