Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2014
Publication Date: 12/25/2014
Citation: Liu, S., Rich, J.O., Anderson, A.M. 2014. Antibacterial activity of a cell wall hydrolase from Lactobacillus paracasei NRRL B-50314 produced by recombinant Bacillus megaterium. Journal of Industrial Microbiology and Biotechnology. 42:229-235.
Interpretive Summary: This study reports the discovery of a novel cell wall hydrolase from Lactobacillus paracasei NRRL B-50314. Because misuse or overdose of conventional chemically synthesized or semi-synthetic antibiotics, their residues can be accumulated in the environment and lead to the emergence of multi-drug resistant strains. New bactericidal compounds are needed to treat infections of multi-drug resistant strains. In the present study, the gene encoding a unique cell wall hydrolase from L. paracasei NRRL B-50314 was cloned and expressed in Bacillus megaterium. The full length recombinant protein contains antibacterial activity and this study will be of interest to researchers to develop biodegradable agents controlling bacterial infections.
Technical Abstract: This study reports the production and characterization of a novel antibacterial polypeptide, designated laparaxin, which is secreted by Lactobacillus paracasei NRRL B-50314. Crude laparaxin has antibacterial activity against a range of Gram-positive bacteria including the following: lactic acid bacterium Lactococcus lactis; Lactobacillus buchneri; the food-borne pathogen Listeria monocytogenes; the gastrointestinal pathogen Enterococcus faecalis; the opportunistic pathogen Staphylococcus aureus methicillin sensitive (MSSA) strains SH1000, 209P and DU4916S, 1316 P+M-, and 1316 P-M-, methicillin-resistant S. aureus (MRSA) strains COL, 592S, a hetero-vancomycin-intermediate methicillin resistant strain (HeteroVISA also MRSA) MM66, and homogeneous vancomycin intermediate (Homo VISA) 1316 p-m+V5, 1316 p-m+V20. Using L. lactis as indicator strain, the inhibitory activity of crude laparaxin was detected originally in early log phase, and the activity maximizes at the early stationary phase and remains stable after prolonged incubation. Laparaxin activity is stable after 30 min of incubation at 94oC. Higher concentrations of inhibitory activity are produced when glucose, fructose, and sucrose are used as carbon-sources in growth media. Crude laparaxin has potential applications in food and feed industries as well as in clinical and veterinary medicine.