Evaluation of antimicrobial activities of probiotic bacterial culture supernatants against liver abscess-causing bacterial pathogens

Objective

The objectives of our study were to evaluate the abilities of probiotic bacterial culture supernatants to inhibit the liver abscess-causing pathogens Fusobacterium necrophorum, Trueperella pyogenes, and Salmonella enterica in pure cultures or in an in vitro rumen simulating batch culture of rumen microbial model.

Materials and Methods

Probiotic bacterial species were cultured, centrifuged, filter sterilized, and stored at −20°C. Liver abscess-causing pathogens were cultured in anaerobic brain-heart infusion broth (for Fusobacterium) and in Muller-Hinton broth (for S. enterica and T. pyogenes), each with and without probiotic culture supernatants. Bacterial growth was measured in a spectrophotometer or by spread-plating on blood agar, or both.

Results and Discussion

Only the supernatant of L. helveticus reduced the growth of both Fusobacterium subspecies, T. pyogenes, and S. enterica. Addition of L. helveticus supernatant to in vitro batch culture of rumen microbes containing ruminal fluid, buffer, and substrates (glucose, lactic acid, or ground cattle feed) exhibited reduction in the spiked culture of F. necrophorum.

Implications and Applications

Probiotic cultures, such as L. helveticus, may have potential for use as a feed supplement to control liver abscesses.