Solvent extraction of Lactobacillus plantarum supernatant compounds and investigation of its antibacterial effects

BACKGROUND AND OBJECTIVESInterest in probiotics and probiotic-based functional foods has grown enormously during the last few years. The internationally endorsed definition of probiotics is live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Lactic acid bacteria (LAB) as Gram-positive, catalase-negative, and non-spore forming bacteria are the major group of probiotic technologically suitable microorganisms. This study was designed to determine the most potent antibacterial compounds from the solvent extraction of culture supernatant of a L. plantarum strain isolated from cheese.MATERIALS AND METHODSPrimarily, the cheese sample was prepared from East Azerbaijan province. Isolation of Lactobacillus bacteria and Sequencing were performed. A cell-free supernatant was prepared by ۲۰ min centrifugation at ۱۲۰۰۰ rpm, ۴°C, followed by passing through ۰.۲۲-micron filter. Sample was extracted successively with n-hexane and ethyl acetate (EtOAc) at room temperature. The extracts were concentrated under reduced pressure at ۴۰°C using a Rotary evaporator instrument and kept at ۴ °C to be further analyzed by in vitro antimicrobial assay. The MIC values of n-hexane and ethyl acetate extracts of the supernatant were determined against Staphylococcus aureus ATCC۱۲۶۰۰, Escherichia coli ATCC۱۱۷۷۵, Shigella flexneri, Salmonella Typhi PTCC۱۶۰۹, Pseudomonas aeruginosa ATCC۲۷۸۵۳, Pseudomonas aeruginosa ATCC۱۰۴۵ Candida albicans ATCC۱۰۳۲۱, Streptococcus mutans ATCC۳۵۶۶۸, Propionibacterium ۹۸-۶۹۱۲ and Bacillus subtilis ATCC۶۰۵۱.RESULTS AND DISCUSSIONSequencing results led to the identification of Lactobacillus plantarum as the selected LAB isolate. We identified four species from the cheese sample and submitted ۱۶S RNA genome data to national center for biotechnology information (NCBI) gene bank. The named gene data are available via accession numbers: OR۱۵۷۹۵۹, OR۱۵۷۹۵۸, OR۱۵۷۹۵۷, OR۱۴۵۱۴۶. The antimicrobial assay resulted in identification of the EtOAc extract as the best sample against Escherichia coli, Staphylococcus aureus, Shigella flexneri, Salmonella Typhi, Pseudomonas aeruginosa ATCC۲۷۸۵۳ and ATCC۱۰۴۵, Bacillus subtilis, Propionibacterium, Streptococcus mutans, Candida albicans, with MIC values of ۱۶, ۴, ۸, ۸, ۴, ۸, ۴, ۴, ۸, ۳۲ mg/ml, respectively.CONCLUSIONEthyl acetate extract played a dominant role and exhibited significant activities with promising MIC values of ۴ mg/mL against some assessed microbial strains. Further chemical analysis of this extract for determination of effective antibacterial compound (s) are now is underway in our institute.

کلیدواژه ها:

Probiotic ، Solvent extraction ، Antibacterial effects.