Inhibitory activity against the fish pathogen Lactococcus garvieae produced by Lactococcus lactis TW34, a lactic acid bacterium isolated from the intestinal tract of a Patagonian fish

Abstract

After enrichment of Odontesthes platensis intestinal contents, 53 lactic acid bacteria (LAB) were isolated. From the four isolates that showed inhibitory activity against Lactococcus garvieae 03/8460, strain TW34 was selected because it exerted the strongest inhibition. It also inhibited other Gram-positive bacteria, but not Gram-negative fish pathogens. Phenotypic and 16S rDNA phylogenetic analyses showed that TW34 belongs to Lactococcus lactis. In addition, TW34 showed to be sensitive to different antibiotics. The production of the inhibitory agent against L. garvieae was growth associated, and it was significantly influenced by the incubation temperature. The optimal temperature for the antimicrobial production was as low as 15 degrees C. Both acidification and hydrogen peroxide production were ruled out as the source of inhibition. In contrast, the antimicrobial activity was completely lost by treatment with proteolytic enzymes, which confirmed that the inhibitory substance was a bacteriocin. The bacteriocin was highly thermostable (121 degrees C for 15 min) and active between pH 3 and 11. It remained stable for up to 2 months when stored at 4 degrees C and up to 6 months at -20 degrees C. Our results suggest that the strain L. lactis TW34 could provide an alternative for lactococcosis control and therefore be considered for future challenge experiments with fish.

Synergistic antimicrobial action and potential application for fish preservation of a bacteriocin produced by Enterococcus mundtii isolated from Odontesthes platensis

“…Moreover, it has been observed that bacteriocins are able to inhibit other Gram positive bacteria genera including Bacillus and Staphylococcus. However, no inhibitory activity against Gram negative bacteria was found in these studies (Pinto et al, 2009;Rivas et al, 2012;Sequeiros, Vallejo, Marguet, & Olivera, 2010). It must be noted that CFS from E. mundtii Tw56 showed antibacterial activity against Ps.…”

In vivoandin vitroassessment ofLactobacillus acidophilusas probiotic for tilapia (Oreochromis niloticus, Perciformes:Cichlidae) culture improvement

“…; Desriac et al . ; Sequeiros, Vallejo, Marguet & Olivera ), short fatty acids (Vázquez et al . ), organic acids (Midolo, Lambert, Hull, Luo & Grayson ), hydrogen peroxide and carbon dioxide (Naidu, Bidlack & Clemenns ) that may act in synergy to inhibit or kill bacteria.…”

Nisin Z Production by Lactococcus lactis subsp. cremoris WA2-67 of Aquatic Origin as a Defense Mechanism to Protect Rainbow Trout (Oncorhynchus mykiss, Walbaum) Against Lactococcus garvieae

“…mesenteroides CLFP 196, which produce antimicrobial substances against L. garvieae. Moreover, Sequeiros et al (2010) described the isolation of four LAB strains from the intestinal tract of Patagonian fish (Odontesthes platensis) with antimicrobial activity against L. garvieae, including the putative bacteriocinogenic strain L. lactis TW34. Regarding in vivo tests, the supplementation of fish feed with the probiotic putative bacteriocinogenic strains Lb.…”