Molecular Characterization and Evaluation of Antimicrobial potential of Actinobacteria Isolated from Lakes and Rivers of Mizoram

Abstract

The thesis aims to isolate actinobacteria from freshwater sediments from 4 rivers and 2 lakes, screen them for their antimicrobial activity and their ability to produce bioactive compounds. A total of 115 actinobacteria (16 genera) were isolated, identified using 16S rRNA gene sequencing. Streptomyces constitutes the dominant genus (55% of total isolates). To the best of our knowledge, Leucobacter, Zhihengliuella, Amycolatopsis, Prauserella and Promicromonospora were reported for the first time from freshwater. SCA was proposed as the best medium for the isolation of freshwater actinobacteria. 49.7% of the isolates showed inhibition activity against at least one of the tested 5 fungal pathogens. 66.1% of them found to inhibit the growth of at least one tested 6 bacterial pathogens. Nine Streptomyces were selected based on their antimicrobial potential and showing good EC50 value. Biosynthetic genes PKS-II, phzE and NRPS genes were detected and amplified in 31 isolates. 19 isolates were found to have good xylanolytic and cellulolytic activity. 9 selected isolates were investigated to determine their bioactive compounds using GC-MS, which revealed 63 compounds. To best of our knowledge, the compounds detected have never been reported so far from freshwater actinobacteria. Antimicrobial and antifungal compounds were detected and quantified in methanolic crude extracts of the selected actinobacterial isolates using UPLC-MS/MS, Thus, from the present investigation, we conclude that further exploration of freshwater actinobacteria for its potential besides investigation on the purification of potent compounds detected and transformation into drugs will certainly explicate their efficacy in pharmaceutical industry.