Effect of Enterococcus faecium as a Water and/or Feed Additive on the Gut Microbiota, Hematologic and Immunological Parameters, and Resistance Against Francisellosis and Streptococcosis in Nile Tilapia (Oreochromis niloticus)

Abstract

In the present study, we evaluated the effects of administering Enterococcus faecium in food and/or water on the hematological and immunological parameters, intestinal microbiota, resistance to bacterial diseases (streptococcosis and francisellosis) and growth of Nile tilapia. Before the in vivo experiment, probiotic bacteria isolated from Nile tilapia were selected via inhibition tests. Sequencing, annotation, and assembly of the complete genome of the selected bacteria as well as other tests were performed using bioinformatics tools. Three treatments were implemented: G1 (probiotic feeding), G2 (probiotic in water), and G3 (probiotic in food and water); and a negative control (NC) was also employed. Treatment lasted 38 days, and each group consisted of fish and two repetitions. The fish were divided and infected with Streptococcus agalactiae S13 (serotype Ib) and Francisella orientalis. The G1 group had a higher average final weight gain than the G2, G3, and NC groups. Further, a significant increase in the number of thrombocytes was observed in the groups administered probiotics in the diet (G1 and G3). A statistical difference was observed in the mortality of fish infected with S. agalactiae in the NC compared to the treated groups. Cetobacterium was the 43 most abundant genus in the intestinal microbiota of all groups, including the NC group. E. faecium increased the immunity of fish administered the treatment and decreased the mortality caused by S. agalactiae. As an autochtone probiotic, E. faecium does not interfere with the local ecosystem and thus has a great probiotic potential for Nile tilapia in Brazil.

Exploring choices of early nutritional support for patients with sepsis based on changes in intestinal microecology

“…were significantly low in the SPN group. In animal studies, it has been demonstrated that Enterococcus can effectively improve animal growth[ 16 , 17 ], enhance the absorption of other nutrients[ 18 ], and is a beneficial additive, which is widely used in animal feeds. Current research suggests that drug-resistant strains of Enterococcus may be pathogenic[ 19 ]; however, its commensal strains have been identified as probiotics in animal and human intestines[ 20 ].…”

Assessing the effect of probiotics on tilapia lake virus‐infected tilapia: Transmission and immune response

“…However, the protection of hatchlings or larvae is the most challenging part since delivery of probiotics during early stage is quite difficult. As a result, inoculation of probiotic strains to hatchlings or larvae could be a promising alternative strategy to food or water additives (Hasan & Banerjee, 2020; Suphoronski et al., 2021). The dose–response profiles or epidemiological parameter estimates could also be achieved with the present constructed mathematical/epidemiological models by incorporating the field data for better control of TiLV outbreaks in early stages of tilapia farming.…”