Antimicrobial activity of Lactobacillus pentosus against the Bacillus cereus and Klebsiella pneumoniae strains.

Abstract

Food safety is the primary concern of the food industry. The aim of the current research is to study the antimicrobial effects of cell-free supernatant of Lactobacillus pentosus against Bacillus cereus and Klebsiella pneumoniae. B. cereus and K. pneumoniae were isolated from infant formula milk product and meat sample, respectively. Their identification was performed through morphological characterization and biochemical testing. Molecular identification of K. pneumoniae was based on 16s ribotyping. A previously isolated and reported strain of L. pentosus was used for the isolation of CFS (Cellfree supernatants). Antimicrobial activity was studied through agar well diffusion assay. Inhibitory activity was recorded by measuring the zone of inhibition. CFS activity was evaluated for temperature and pH. The antimicrobial activity of CFS of L. pentosus produced at different temperatures and pH was investigated against B. cereus and K. pneumoniae. A clear zone of inhibition was observed against B. cereus while no ZOI was formed against K. pneumoniae. K. pneumoniae was found resistant to the CFS. Crude bacteriocin exhibited heat stability for a temperature of 121°C for 30 minutes and pH range of 3-7. The current study concluded that bacteriocin produced from L. pentosus can be used for the control of B. cereus. Its heat and pH stability allows its potential therapeutic use in the food industry as a food preservative and to control food poisoning cases due to B. cereus. K. pneumoniaeis was found resistant to the isolated bacteriocin, and therefore L. pentosus cannot be used for control against K. pneumoniae.