Bacteriocin-producing strain of Enterococcus faecium EK 13 with probiotic character and its application in the digestive tract of rabbits
AbstractEnterococcus faecium EK 13 is a bacteriocin-enterocin A producing strain with probiotic properties. In this study its colonization, stability and effect on microflora in rabbits was studied as well as its influence on zootechnical parameters. Fifty rabbits of both sexes (HYPLUS, 30-day old; after weaning) were divided into control (CG) and experimental (EG) groups. They were fed a standard diet. Moreover, 25 rabbits in EG were fed daily (for 4 weeks) 15 g (separate doses ∼1.6 g) of lyophilized EK13 strain (rifampicin resistant variant — rifR; 109 cfu/g) dissolved in drinking water. After cessation of EK13 (rifR) strain application, the rabbits in both groups were fed a standard diet for the next 2 weeks. Sampling was performed in double on day 0 (at the beginning of experiment), weekly during EK13 (rifR) strain application as well as on week 1 and 2 after cessation of EK13 (rifR) strain application. The counts of EK13 (rifR) strain reached 7.1 ± 2.6 log10 cfu/g after 4 weeks and even on week 2 after its cessation the counts 5.6 ± 2.3 log10 cfu/g were determined. The total counts of enterococci in the rabbits were already increased in EG comparing with CG (p < 0.05); even 2 weeks after EK13 (rifR) strain cessation, their counts in EG were 7.2 ± 2.6 log10 cfu/g (p < 0.001). Enterococci in CG reached at the same time the value 3.7 ± 2.6 log10 cfu/g. The counts of E. coli were significantly reduced in EG during 4 weeks (p < 0.05, p < 0.001). Even 2 weeks after EK13 (rifR) strain cessation significant difference in E. coli counts between CG and EG was detected (p < 0.001). Enterobacteria in EG were significantly reduced (p < 0.001). Average daily gain in EG was 41.0 ± 3.83 in comparison to CG (40.6 ± 3.72); it means almost the same; although rabbits in EG showed higher feed intake per kg of gain than rabbits in CG. Preliminary results demonstrated that EK13 is a perspective probiotic candidate for rabbits.