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Vet Microbiol ; 151(3-4): 336-44, 2011 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-21531092

RESUMO

Red-leg syndrome (RLS) is one of the main infectious diseases that cause economic losses in Lithobates catesbeianus hatcheries, Citrobacter freundii being an etiological agent. Treatment or prevention with therapeutics or chemicals results in modifications of the indigenous microbiota, development of antibiotic resistance, presence of their residues in food and enhancement of production costs. Thus, probiotics could be used as an alternative therapy. Lactic acid bacteria are part of the indigenous microbiota of healthy frogs and can prevent pathogen colonization by different mechanisms, including the production of antagonistic substances. In this work, the evaluation and characterization of the inhibition of C. freundii CFb by Lactococcus lactis subsp. lactis CRL 1584, a potentially probiotic candidate, were carried out. This strain produced lactic acid, H(2)O(2) and bacteriocin in static and shaken conditions and inhibited pathogen growth in associative cultures, with an earlier inhibition under agitated conditions. The elimination of each of the antimicrobial metabolites partially abolished the inhibition of the pathogen, suggesting that the inhibitory effect could be attributed to a combined action of the three antagonistic molecules. Electron microphotographs revealed the damage caused by L. lactis CRL 1584 supernatants to C. freundii cells. The addition of pure lactic acid, H(2)O(2) and bacteriocin to the culture media showed that each metabolite caused different morphological modifications in C. freundii, in agreement with the effect on viable cell counts. The results support the possibility that L. lactis CRL 1584 might be considered as a probiotic to be used in the prevention of RLS in raniculture.


Assuntos
Citrobacter freundii/patogenicidade , Infecções por Enterobacteriaceae/veterinária , Lactococcus lactis/fisiologia , Probióticos , Ranidae/microbiologia , Animais , Antibiose , Bacteriocinas/biossíntese , Citrobacter freundii/ultraestrutura , Meios de Cultura/metabolismo , Infecções por Enterobacteriaceae/prevenção & controle , Peróxido de Hidrogênio/metabolismo , Ácido Láctico/biossíntese , Lactococcus lactis/metabolismo
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