Antibacterial potential of Actinobacteria from a Limestone Mining Site in Meghalaya, India

Abstract

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.

Antimicrobial Efficiency of a Marine Streptomyces sp. VPTSA1-4 Isolated from Coromandel Coast of Bay of Bengal, India

“…However, the screening phenomenon of several actinobacterial isolates is very essential to find out the potential antagonist. Similar to our study, it has been reported that around 30% of actinobacteria isolated from a marine source have antagonistic activity 8,16 whereas, 19% of isolates from the limestone mining area of Mawsmai near Sohra, Meghalaya had antibacterial activity 20 , in contrast to these results, 48.1% of actinobacteria from the soils of Kalapatthar (5545 m) Mount Everest Region with antibacterial activity 21 and as much as 53% of the actinobacteria exhibited antimicrobial activity 22 . The capability of ethyl acetate in the solubilisation of antimicrobial compounds obtained from actinobacteria is already reported by many workers 8,16,23 .…”

Rhizospheres of Rubus ellipticus and Ageratina riparia from Meghalaya exhibit Actinomycetota that promote plant growth

“…The culture filtrates were evaluated for antibacterial activity against Escherichia coli MTCC 1669, Pseudomonas aeruginosa MTCC 4673, Staphylococcus aureus MTCC 9886, Bacillus subtilis MTCC 1305, and anticandidal activity against Candida albicans MTCC 7253 by following the agar well diffusion method described by Syiemiong and Jha [25], except that the incubation was carried out under stationary condition at 30 ± 2°C for 30 days. The cultures were also evaluated for antagonistic activity by dual culture against phytopathogenic bacterial and fungal strains, namely, Xanthomonas campestris pv.…”

“…Detection of BGCs, namely, Type I polyketide synthase (PKS-I), type II polyketide synthase (PKS-II), and non-ribosomal peptide synthetase was carried out according to the method described by Syiemiong and Jha [25].…”

Comparison of Actinobacteria communities from human‐impacted and pristine karst caves

“…Actinobacteria represent important cave dwellers, and many are potentially pathogenic (Jurado et al, 2010 ), biotechnologically relevant (Bhullar et al, 2012 ; Hamedi et al, 2019 ; Syiemiong & Jha, 2019 ), and novel (Fang et al, 2017 ; Jurado et al, 2008 ; Jurado, Kroppenstedt, et al, 2009 ; Rangseekaew & Pathom‐Aree, 2019 ) species have been identified in these environments. Actinobacteria can dominate in both anthropized (Gonzalez‐Pimentel et al, 2018 ) and pristine caves (De Mandal et al, 2017 ); however, some actinobacterial taxa are specific to one cave type.…”