Isolation and characterization of antibiotic producing bacterial strains from red soil of Himalayan region of Pakistan

Abstract

The emergence of multi drug resistant microbial pathogens has become a global health challenge and set a dire requirement of searching new effective antimicrobials. Soil is an ultimate reservoir of biologically active micro flora, which harbors trillions of microbial strains producing compounds of commercial interest. Hence aim of the present study was an attempt to isolate and identify the antibiotic producing microbial strains from the red soil of Himalayan an unexplored region of Pakistan. In this study from 10 different soil samples only one bacterial strain was isolated capable of antimicrobial activity. Strain was identified by biochemical characteristics and final identification was done by API 20 NE kit which showed 99% homology with P. aeruginosa. Hence the strain was identified as P. aeruginosa S2. Antibacterial and antifungal activity of the P. aeruginosa S2 showed that Staphylococcus aureus was extremely sensitive to it with a zone of inhibition of 42mm. Staphylococcus epidermidis, Enterobacter aerogenes, Aspergillus fumigatus and Candida albicans were also inhibited by the isolated strain. Effect of Glycerol, Copper sulphate (CuSo4), Sodium sulphate (Na2SO4) and Glycerol on antibiotic production was also evaluated by supplementing growth media with these chemicals. Pseudomonas aeruginosa was grown in bulk quantity using solid state fermentation and crude extract was prepared using organic solvents and subjected to silica gel column chromatography for purification of active compound. Purified compound showed antibacterial against human pathogens. The unexplored Kashmir Himalayas are of great significance because of its richness in biodiversity and need to be explored for isolation and characterization of native microbes for biologically active secondary metabolites. This un touched region may be considered as hub of new antimicrobials and may have applications in natural product-based drug discovery