Isolation of antimicrobial actinomycetes from the soil surrounding different medicinal plants of saurashtra and characterization of antimicrobial compounds therefrom

Abstract

quotBackground: In the last few years, resistance developed by microorganisms against antibiotics has rapidly increased. The global health sector faces a huge obstacle for the treatment of various diseases. There is a need to look at alternate sources like microorganisms from which new and useful substances against various diseases can be obtained. newlineAim: To screen the soil surrounding medicinal plants possessing antimicrobial activity in order to find soil bacteria capable of producing useful antibiotics across various regions of Saurashtra. newlineMaterials and Methods: In the present study, 11 medicinal plants and 3 regions of Saurashtra were selected. Several microscopic and morphological methods were used for studying colony characteristics. Cross streak, agar well and disk diffusion methods were used for screening. TLC, bioautography, various biochemical tests, enzymatic activity, 16S rDNA sequencing, gel electrophoresis were done followed by optimization study. Extraction and characterization was done of most potent isolate using UV, FTIR, NMR, MASS, and in vitro microbial assay. newlineResults and Discussion: Sixty six isolates of Actinomycetes were obtained, out of which 51.72% belonged to Streptomyces genus. 68.2 % of isolates showed activity in primary screening. Isolate GOS1 was found most potent, which was confirmed as Streptomyces arenae. Media (starch casein agar), carbon source (starch, maltose), KNO3 (2%), 36 °C, pH 8, sodium chloride (3 g/l), K2HPO4 (2.5 g/l), humic acid (1 g/l) under shaking condition for 8 days were best, based on optimization study. More actinomycetes isolates had antimicrobial activity produced from soil nearby the medicinal plant area than those not nearby the plants. Isolate from soil near Ocimum sanctum of Gir Somnath was capable to produce an antimicrobial compound having the capability to restrict the growth of various pathogens. newlineConclusion: Soil surrounding medicinal plants which themselves have well-known antimicrobial activity can be a rich source of actinomycetes which can produce