Enterocin M in Interaction in Broiler Rabbits with Autochthonous, Biofilm-Forming Enterococcus hirae Kr8 Strain

Abstract

Young rabbits are susceptible to gastrointestinal diseases caused by bacteria. Enterococcus hirae can be associated with diseases. But enterocins produced by some enterococcal species can prevent/reduce this problem. Therefore, the interaction of enterocin M with a biofilm-forming, autochthonous E. hirae Kr8⁺ strain was tested in rabbits to assess enterocin potential in vivo. Rabbits (96), aged 35 days, both sexes, meat line M91 breed were divided into four groups, control C and three experimental groups. The rabbits in C received the standard diet, rabbits in experimental group 1 (E1) received 10⁸ CFU/mL of Kr8⁺, a dose 500 µL/animal/day, E2 received Ent M (50 µL/animal/day), and E3 received both Kr8⁺ and Ent M in their drinking water over 21 days. The experiment lasted 42 days. Feces and blood were sampled at day 0/1 (at the start of the experiment, fecal mixture of 96 animals, n = 10), at day 21 (five fecal mixtures per group, n = 5), and at day 42 (21 days after additives cessation, the same). At days 21 and 42, four rabbits from each group were slaughtered, and cecum and appendix were sampled for standard microbial analysis. Ent M showed decreased tendency of Kr8⁺. Using next-generation sequencing, the phyla detected with the highest abundance were Firmicutes, Verrucomicrobia, Bacteroidetes, Tenericutes, Proteobacteria, Cyanobacteria, Saccharibacteria, and Actinobacteria. Interaction of Ent M with some phyla resulted in reduced abundance percentage. At day 21, significantly increased phagocytic activity (PA) was found in E1 and E2 (p < 0.001). Kr8⁺ did not attack PA and did not stimulate oxidative stress. But Ent M supported PA. The prospective importance of this study lies in beneficial interaction of enterocin in host body.

Keywords: Biofilm; Broiler rabbits; Enterocin; Enterococcus hirae; Susceptibility.