Antagonistic effects of B. subtilis against E. coli

Microorganisms release volatile organic compounds (VOCs) as part of their metabolisms, one of which as a form of response when other microorganisms are present within their niche. These VOCs can have different effects on the microorganism under study. Some VOCs have been studied due to their antagonistic effects on pathogenic bacteria. VOCs emitted by B. subtilis, prevalent Gram-positive bacteria, have been widely studied because of their antimicrobial properties. In this study, the pathogenic Gram-negative bacteria E. coli were exposed to the VOCs emitted by B. subtilis for a certain period of time under aerobic conditions. Bacterial solutions were extracted for the (1) viability of both bacteria which was determined using plate count, and (2) proteomic analysis to ascertain how the presence of B. subtilis and its emitted VOCs affect E. coli. Furthermore, the VOCs of both B. subtilis and E. coli were collected and identified using GC-MS/TDU method. Key results from these analyses have shown that B. subtilis have antagonistic effects on E. coli, wherein some of E. coli’s stress-related response proteins as well as proteins related to virulence where downregulated. The results highlight B. subtilis possessing a great potential as an anti-bacterial agent against the pathogenic bacteria E. coli.