Purification and molecular characterization of antibacterial compounds produced by Lactobacillus murinus strain L1.
OBJECTIVE
The aim of this work was to purify and characterize antibacterial compounds produced by Lactobacillus murinus strain L1.


RESULTS
Antagonistic activity was observed in a deferred agar-spot assay against spoilage and pathogenic bacteria, but not against lactobacilli. The inhibitory activity occurred between pH 3.0 and 5.0, and was heat stable. The active compounds were purified by gel filtration chromatography and two peaks of antibacterial activity were observed using Bacillus cereus ATCC 11778 and Shigella sonnei ATCC 11060 as indicator strains. Two active low molecular weight compounds were responsible for this phenomenon and UV spectroscopy, gas chromatography and mass spectrometry were used to characterize them. One of them is lactic acid, while the other is a mono-substituted aromatic ring apparently constituted by group residues of m/z 192 linked in tandem to phenylalanine.


CONCLUSIONS
Lactobacillus murinus produces at least two low molecular weight compounds active against B. cereus and Sh. sonnei.


CONCLUSIONS
This is the first purification of a new broad-spectrum antibacterial compound from Lact. murinus which inhibits various pathogenic and food spoilage bacteria without acting on other lactobacilli. Using it as a biotechnological control agent of bacterial spoilage may be a promising possibility for the food industry.
Nardi
R M D
RM
Departamento de Microbiologia, ICB, Universidade Federal de Minas Gerais, 30161-970 Belo Horizonte, MG, Brazil. nardi@icb.ufmg.br
Santoro
M M
MM
Oliveira
J S
JS
Pimenta
A M C
AM
Ferraz
V P
VP
Benchetrit
L C
LC
Nicoli
J R
JR
D000818:Animals; D000900:Anti-Bacterial Agents / Q000302:isolation & purification*; D001409:Bacillus cereus / Q000187:drug effects; D002849:Chromatography, Gas / Q000379:methods; D002850:Chromatography, Gel / Q000379:methods; D003470:Culture Media; D005243:Feces / Q000382:microbiology; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012764:Shigella sonnei / Q000187:drug effects; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013696:Temperature
D000900:Anti-Bacterial Agents; D003470:Culture Media; D010447:Peptide Hydrolases