Bacteria Exhibiting Antimicrobial Activities; Screening for Antibiotics and the Associated Genetic Studies

A total of 118 bacterial strains were isolated from six different soil samples from different parts of Pakistan. 50 out of these strains exhibited antagonistic activities against at least two or more strain from a panel of pathogenic and nonpathogenic microorganisms. Tested strains included three sets; environmental, laboratory and multidrug resistant clinical isolates. Twelve strains exhibited diverse spectrum of activity are focus of further work. The bacterial species identified include Bacillus subtilis, B. amyloliquefaciens, B. cereus, and B. licheniformis. Identified strains showed interesting biological activities e.g. inhibiting the growth of clinical isolates (Klebsilla species), strong antifungal and anti-algal activities and high toxicity against Artemia sp., while their TLC and HPLC profile showed an impressive chemical diversity. All the strains were able to produce number of peptides (surfactins, iturins, fengycins, subtilin and subtilosin) in different combinations. Presence of sboX gene was not correlated with subtilosin production, however, subtilosin and sboX were confirmed in Bacillus amyloliquefaciens for the first time.