Abstract

SCREENING OF SOIL STREPTOM YCES AS A POTENTIAL SOURCE OF ANTIBIOTICS ACTIVE AGAINST PATHOGENIC BACTERIA

Harjot Pal Kaur*, Sukhvir Kaur and Smriti Chauhan

ABSTRACT

Microbial pathogens are developing resistance against existing antibiotics, stressing the urgency for discovery of new therapeutic compounds. The chances of isolating undiscovered strains from the terrestrial habitats have diminished so that the search for novel products has switched to rare genera of microorganisms from normal habitats. So the focus of this study was to assess the antibiotic potential of soil Streptomyces against pathogenic bacteria. Ten isolates obtained from diverse habitats including agricultural sites, rhizosphere, barn soil and wasteland were purified on actinomycete isolation agar, then characterized morphologically and biochemically which confirmed that seven of them belonged to Streptomyces genus. Streptomyces isolates were then evaluated for their inhibitory activities against Gram positive and Gram negative pathogenic bacteria such as Staphylococcus aureus, Bacillus subtilis (Gram positive), Escherichia coli and Pseudomonas aeruginosa (Gram negative). Four isolates out of the tested seven isolates, exhibited antibacterial activity which were isolated from wasteland soil, barn soil and rhizosphere. All the four isolates inhibited the growth of tested Gram positive bacteria and maximum inhibition zones were found to be 19 mm and 18 mm against S. aureus and B. subtilis respectively. Among Gram negative bacteria E. coli was least susceptible with inhibition zone of 10 mm. Further investigations are needed to explore highly potent antibiotic producers from soil and that can be used more effectively against pathogenic diseases by optimizing antibiotic production conditions.

Keywords: Antibiotics, Antimicrobial, Pathogenic, Inhibition zone, Rhizosphere.