Antimicrobial Activity of Extracts Bacillus Species Isolated From Baghdad Soil Against Some Human Pathogenic Microorganisms

Abstract

Bacillus species are the predominant soil bacteria because of their resistant endospore   formation and can produce many different antimicrobial substances.

            The main aim of this study was to isolate Bacillus species from soil and investigate their antimicrobial activity against some pathogenic bacteria and fungi isolated from human.

            48 soil samples were collected from different region of Baghdad city (Rashidiya, Mahmudiyah, Alkraat and Aldora) during December 2015 and analyzed for the presence of Bacillus species. Bacterial isolates were identified by using different microscopical examination, cultural characteristics, biochemical tests and confirmed by VITEK 2 bacterial identification system. The antimicrobial effects of Bacillus species extracts against some pathogenic bacteria (Gram-positive, Gram-negative) and fungi were examined. The identified Bacillus species included B.  polymyxa, B. cereus, B. licheniformis, B.  mycoides, B.  firmus and B.  subtilis.

            The results indicate that the bacterial isolates showed antimicrobial activity against all tested pathogenic bacteria and fungi. B. polymyxa showed best activity against most test organisms compare to other Bacillus isolates, follow by B. subtilis, B. cereus, B. licheniformis, B. firmus and B. mycoides.

           This study reveals that some Bacillus species have the ability to produce antimicrobial compounds that can be used to control microbial infections in future.