Dietary supplementation of Bacillus subtilis and Enterococcus faecalis can effectively improve the growth performance, immunity, and resistance of tilapia against Streptococcus agalactiae

Abstract

The combined probiotics (four different combination of Bacillus subtilis, Bacillus licheniformis and Enterococcus faecalis) were used and the growth performance, immunity, gut morphology and resistance to Streptococcus agalactiae of tilapia (Oreochromis mossambicus) were comprehensively evaluated after 42 days feeding on supplemented diets. Results showed that the growth performance of tilapia in PG2 (with B. subtilis and E. faecalis) was the best. Moreover, the strong positive association of some indices with specific probiotics was demonstrated for lipase activity, SI, LYZ, C3, T‐AOC and CAT were higher in PG2, indicating that the specific probiotics, and not diversiform probiotics, were the key determinants of the results for tilapia. The better gut villi length, villi width and muscular thickness in fishes under PG2, which shows that specific probiotics can promote the good development of gut mucosal structure of tilapia. Over 76% survival rate for tilapias against S. agalactiae in the PG2 may be because the B. subtilis and E. faecalis provided a better gut micro‐ecological environment. Totally, B. subtilis and E. faecalis may be specific to tilapia gut microbes.

Effects of different water quality regulators on growth performance, immunologic function, and domestic water quality of GIFT tilapia

“…Herein, BS and CS can significantly improve the growth performance of GIFT tilapia, reduce CF, and contribute significantly to growth enhancement. According to the findings of Liu et al ., bacillus subtilis can provide a better intestinal flora environment for tilapia as well as improve intestinal absorption and metabolism of nutrients to promote tilapia growth [ 25 ]. Similarly, CS can promote tilapia growth by increasing feed conversion rate [ 26 , 27 ].…”

“…Related studies have shown that NO and its oxygen metabolites are released into serum when macrophages and some non-immune cells are activated [ 45 ], which play a role in signal transduction and scavenging oxygen free radicals in the body [ 46 ]. Many studies have shown that adding BS to feed can increase the activities of LZM, SOD, ACP and AKP, and T-AOC in the serum of GIFT tilapia [ 25 ]. Similarly, CS can promote tilapia growth and improve SOD, LZM, and other enzyme activities in serum, thus enhancing the disease resistance to Aeromonas hydrophila [ 26 ].…”

“…TNF- α is an important pro-inflammatory cytokine in the TNF family, which can clear the infection by activating immune cells and promoting the secretion of other cytokines [ 47 ]. Similarly, IL-1β acts as an important pro-inflammatory cytokine by recruiting more lymphocytes to colonization/invasion sites to accelerate and enhance immune effects [ 25 ]. The expression levels of IL-1β and TNF-α genes in animal bodies have similar indicative significance; upon up-regulating by a large margin, it indicates the occurrence of inflammatory reaction, and a small upward adjustment can indicate that the animal is in a high level of immune preparation [ 33 ].…”

“…The expression levels of IL-1β and TNF-α genes in animal bodies have similar indicative significance; upon up-regulating by a large margin, it indicates the occurrence of inflammatory reaction, and a small upward adjustment can indicate that the animal is in a high level of immune preparation [33]. Interferon-γ (IFN-γ) is a multipotent cytokine that can enhance immunity by activating signal transduction pattern recognition receptors in the congenital and adaptive immune systems [25]. It can affect cell response by regulating the expression level of multiple genes, such as improving NK cell activity and macrophage lysosome activity and promoting antigen presentation [48].…”

Bacillus sp. as potential probiotics for use in tilapia fish farming aquaculture – a review

“…In addition, they aid in the development of the host's digestive system, maintain the balance of intestinal microbiota, and influence the structure of the intestines (Allameh et al, 2016;Dagá et al, 2013). Therefore, probiotics have become vital ingredients in feed supplements, while improving the immune system and growth functions as abovementioned, also inhibiting the growth of pathogens (Amir et al, 2019Tachibana et al, 2021;Moustafa et al, 2021;El-Saadony et al, 2021;Liu et al, 2021;Hassaan et al, 2021). They are a successful and environmentally friendly alternative to antibiotics, improving rearing water quality and the fish's response to stress (Elsabagh et al, 2018).…”