and Activity of L14 Strain Against DC3 Strain.

INTRODUCTION

Domestic poultry is a natural reservoir of , the host-pathogen interaction being predominantly asymptomatic. This study investigated whether chickens remain asymptomatic partly because of lactic acid bacteria (LAB).

MATERIAL AND METHODS

spp. and LAB were isolated from the gut of poultry chickens using enrichment and screening assays and were identified rDNA sequencing. The DC3 isolate was grown in different cell-free supernatants (CFS) generated from a priority LAB isolate. An challenge involving the and LAB isolates using a chicken model was performed to confirm the findings.

RESULTS

Twelve presumptive LAB isolates had anti- activity based on cross-streak and agar plug assays, with L14 isolate exhibiting the highest activity. Inhibition by L14 CFS of the growth of occurred in a dose-dependent manner. DC3 inhibition was most evident in CFS harvested at 72 h and produced by co-culture with the pathogen. Neutralisation of the CFS abrogated the observed inhibition. Co-infection with DC3 and L14 , however, failed to inhibit colonisation in chickens.

CONCLUSION

The results suggest that the anti- effect of L14 in chickens may be due to mechanisms other than direct inhibition of growth.