title: Biological potency and characterization of antibacterial substances produced byLactobacillus pentosusisolated fromHentak, a fermented fish product of North-East India.
abstract: Lactic acid bacteria (LAB) isolated from various foods are important due to their potential to inhibit microorganisms, including drug-resistant bacteria. The objectives of this investigation were to isolate and identify antibacterial substances producing LAB fromHentak, a traditional fermented fish product of Manipur (North-East India), and to optimize the production of antagonistic substances present in cell free neutralized supernatant (CFNS) against enteric bacterial pathogens using the 'one factor at a time' (OFAT) method. Out of 10 LAB, the most potent bacterium producing antibacterial substances was isolated and identified asLactobacillus pentosusstrain LAP1 based upon morphological, biochemical and molecular characterization. MRS (de Man, Ragosa and Sharpe) medium was determined to provide better bactericidal activity (AU/ml) than other tested media against the indicator enteric bacteria, includingStaphylococcus epidermidisMTTC 3615,Micrococcus luteusMTCC 106,Shigella flexneriMTCC 1457,Yersinia enterocoliticaMTCC 840 andProteus vulgarisMTCC 1771. The culture conditions (pH: 5, temperature: 30 °C and inoculum volume: 1 %) and medium components (carbon source: lactose and nitrogen source: ammonium chloride) were observed to be the most influential parameters of significant antagonistic activity of CFNS against the enteric pathogens. MRS medium supplemented with Tween20 effectively stimulated the yield of antibacterial substances. The CFNS of strain LAP1 exhibited sensitivity to proteolytic enzyme (pepsin) treatment and heat treatment (60 °C for 60 min, 100 °C for 30 min and 121 °C for 15 min) and lost its inhibitory properties. The CFNS was active at an acidic (pH 3.0) to neutral pH (pH 7.0) but lost its antagonistic properties at an alkaline pH. The CFNS obtained from strain LAP1 scavenges the DPPH (1,1-diphenyl-2 picrylhydrazyl) significantly in a concentration-dependent manner within the range of 8.8 ± 0.12-57.35 ± 0.1 %. The OFAT-based approach revealed the baseline for statistical optimization, the scale-up process and efficient production of CFNS byL. pentosusstrain LAP1, which could be used as a potential antibacterial and free radical scavenging agent.
authors: Research Department of Plant Biology and Biotechnology, Loyola College, Nungambakkam, Chennai, Tamil Nadu 600034 India.
authors: Chirom
authors: C
authors: Aarti
authors: Research Department of Plant Biology and Biotechnology, Loyola College, Nungambakkam, Chennai, Tamil Nadu 600034 India.
authors: Ameer
authors: A
authors: Khusro
authors: Department of Botany and Microbiology, Addiriyah Chair for Environmental Studies, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451 Saudi Arabia.
authors: Mariadhas Valan
authors: MV
authors: Arasu
authors: Research Department of Plant Biology and Biotechnology, Loyola College, Nungambakkam, Chennai, Tamil Nadu 600034 India.
authors: Paul
authors: P
authors: Agastian
authors: Department of Botany and Microbiology, Addiriyah Chair for Environmental Studies, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451 Saudi Arabia.
authors: Naïf Abdullah
authors: NA
authors: Al-Dhabi
keywords: Antagonistic substances; Cell free neutralized supernatant; Hentak; Lactic acid bacteria; Lactobacillus pentosus; OFAT