ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Debulman Syiemiong1,2 and Dhruva Kumar Jha1
1Microbial Ecology Laboratory, Department of Botany, Gauhati University, Guwahati – 781 014, India.
2Department of Botany, St. Edmund’s College, Shillong – 793 003, India.
J Pure Appl Microbiol, 2019, 13 (2): 789-802 | Article Number: 5647
Received: 01/05/2019 | Accepted: 10/06/2019 | Published: 25/06/2019

This work attempts to assess the antimicrobial potential of actinobacteria isolated from limestone mining sites which hitherto, is an under-explored niche for exploring novel bioactive metabolites. Actinobacteria were selectively isolated from Mawsmai, Meghalaya, India, a limestone mining area, using different pretreatment methods. Forty-seven isolates were obtained, which were identified based on their morphological, biochemical and chemotaxonomical characteristics. Streptomyces was the dominant cultivable genera which constituted 76% of the isolates cultivated. All the isolates were screened for antimicrobial activity against three Gram-negative viz. Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae, and three Gram-positive bacteria viz. Staphylococcus aureus, Bacillus subtilis and Micrococcus luteus and besides, two candidal species viz. Candida albicans and C. tropicalis. 19% of the total isolates showed antibacterial activity against at least one of the test bacterial strains used. The identity of the four bioactive isolates viz. LD-21, LD-29, LD-34 and LD-39 was confirmed as Streptomyces sp. on the basis of their 16S rDNA sequence and 16S rRNA secondary structure analysis. These isolates showed antibacterial activity against at least two Gram-positive bacteria and all the four harbored at least one of the three biosynthetic gene clusters viz. type-I and type-II polyketide synthases and non-ribosomal peptide synthetase which are related to synthesis of bioactive metabolites.


Streptomyces, Antimicrobial, Biosynthetic gene clusters, 16S rRNA secondary structure.

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© The Author(s) 2019. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.