Effect of Gentamicin and Amoxicillin on methicillin resistant Staphylococcus aureus (MRSA) against different time and concentrations; Comparative study of the effect of bitter leaf extract and antibiotics (gentamycin and amoxicillin) on bacterial species isolated from wound.

E3 Journal of Biotechnology and Pharmaceutical Research

E3 Journal of Biotechnology and Pharmaceutical Research Vol. 3 (2) pp. 28 - 41, April 2012; © E3 Journals; ISSN 2141-7474


Heat stable bacteriocin from Lactobacillus paracasei subsp. tolerans isolated from locally available cheese: An in vitro study

Malini M , Savitha J *
Department of Microbiology and Biotechnology, Jnanabharathi campus, Bangalore University, Bangalore - 560056, India.
*Corresponding Author E-mail: drsvtj@yahoo.co.in
Accepted 14 March 2012

Abstract

Lactic acid bacteria (135) were isolated and screened for bacteriocin production by agar overlay method. Among them, Lactobacillus paracasei subsp. tolerans isolated from locally available cheese showed maximum zone of inhibition (24-26 mm) against food borne (Listeria monocytogenes, Staphylococcus aureus) and human pathogens (Escherichia coli, Salmonella typhi). Bacteriocin was found to be proteinaceous in nature, heat stable (1210 C for 15 min) and active over a wide pH range of 4.0-8.0. It showed stability (60 %) for 30 days at room temperature (30- 320C). Addition of surfactants (EDTA, SDS, hexadecyl trimethylamonium bromide) up to 1% to crude bacteriocin showed increase in antibacterial activity where as metal ions (calcium chloride, zinc sulphate and mercuric chloride) in low concentration (0.5-1 mgl-1) decreased the activity. The bacteriocin was purified to its homogeneity by ammonium sulfate precipitation, gel filtration chromatography and HPLC. Molecular weight of bacteriocin was found to be 8.6 and 8.3 KDa by SDS PAGE and LC/MS respectively. Maximum Bacteriocin production was obtained at 35ºC, pH 7.0, NaCl (0.2%) after 28h of incubation. Addition of L-Ascorbic acid increased bactreiocin production. Our present study demonstrates the possibility of using L. paracasei subsp. tolerans as a biopreservative in dairy industry.

Keywords: Lactic acid bacteria, Lactobacillus paracasei subsp. tolerans, Antibacterial activity, Bacteriocin, heat stability

[Download Article - PDF]