Emergence of Antibiotic-Producing Microorganisms in Residential Versus Recreational Microenvironments

AIMS To identify novel antibiotic-producing microbial strains with unprecedented pertinence. We hypothesize that site-specific soil samples will contain a variety of antibiotic-producing species (APS) with diverse specificity of molecular elements. PLACE AND DURATION OF STUDY Laboratory of Microbiology, Division of Biological and Health Sciences, University of Pittsburgh, Bradford, PA-16701, USA, between August 2010 and May 2011. METHODOLOGY The environmental soil samples were collected from residential and recreational sites in Southern, PA, USA at longitude: -76 42 21.7116, latitude: 39 56 35.7252; approximately 201 meters above sea level. Over 70 natural antibiotic-producing soil bacteria were screened against 19 pathogenic microorganisms. Agar-plug assay was established to identify the antibiotics' potency and pathogenic inhibitory index calculations were employed to measure the inhibitory potential of each isolate; 16S rRNA sequencing was used for microbial classification. RESULTS A total of 71 microorganisms from residential soil demonstrated zones of inhibition (ZOI), followed by 9 organisms from recreational soil sample. A total of 15 bioactive strains demonstrated convincing growth inhibitory properties against 16 clinically relevant pathogens; 40% revealed pDNA presence, of which 67% exhibited stringent potencies against S. aureus. We observed a highly bioactive residential soil microbiota compared to recreational soil. CONCLUSION 16S rRNA sequence analysis corroborated several of the species belonging to Enterobacteriaceae, Xanthomonadaceae, and Bacillaceae. These findings may indicate a co-evolutionary biosynthesis of novel antibiotics driven by the increase of bioactive microbiota in residential environments.