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Objective: Isolation of lactic acid bacteria with the potential to
inhibit the growth of pathogenic E. co/i and Salmonella.
Procedures: Samples from different parts of digestive tract of healthy chickens were cultured in MRS broth and incubated at 37°C for 24-48 hours in anaerobic and aerobic conditions. Then,
plates containing MRS agar and Rogosa agar were inoculated with
cells grown in MRS broth previously. Plates were incubated at 37°C for 24-48 hours. Different colonies on MRS agar plates were studied for cultural and morphological characters. The gram positive,
catalase negative, non-spore forming cocci and bacilli which were
unable to produce haemolysis were selected for inhibition assay
against E. coli serotypes (078:K80, 02:Kl, 01:Kl) and Salmonella serotypes (pullorum, enteritidis, typhimurium). The antagonistic properties of isolated lactic acid bacteria were studied by using
agar spot test.
Results: Out of 659 isolated lactic acid bacteria, 139 isolates (21.09%) were able to inhibit growth of indicator strains used in this study. From 139 isolated lactic acid bacteria, of those which
demonstrated antagonistic activity against the pathogens, 31 isolates
were identified as Lactohacillus spp., and the 108 reminder isolates
were Enterococcous spp. The isolated lactic acid bacteria were
more efficient in inhibition of Salmonella than E. co/i. The antagonistic activity observed in this experiment can be attributed
to organic acids and bactenocin production by lactic acid bacteria.
Clinical implications: As the source of isolation of lactic acid bacteria in this study was poultry, and their potential inhibitory
effects against mentioned pathogens and consider to other essential
criteria, it is foreseen that it would be possible to use these isolates
as a feed additive in poultry production in order to reduce the risk of infection.