The adherence and colonization of microorganisms in fish gastrointestinal tract

Abstract

Eggs, gills, skin and intestinal tracts of fish harbour bacterial communities that are thought to impact fish health through their interaction with the tissues. In particular, the gastrointestinal (GI) tract possesses numerous microbes and is considered an infection route. During the infections caused by pathogenic bacteria, mucosal adhesion is a critical early phase and plays an important role in fish development. This review focused on knowledge regarding the adherence and colonization of microorganisms in fish GI tract mucus, including various methods such as in vivo, in vitro, and ex vivo, host specificity, lactic acid bacteria nonfish origin using the adherence of pathogenic bacteria, gnotobiotic approaches and molecular methods. However, probiotics might not be possible to truly colonize the digestive tract of fish. The term 'temporal colonization' might be a better phrase to use when discussing probiotic persistence and presence within the mucosal layer. Recent and promising results in this field were presented based on new perspectives and future research directions of the adherence and colonization of microorganisms in fish GI tracts.

Effects of anEnterococcus faecium‐based probiotic on growth performance and health of Pirarucu,Arapaima gigas

“…Successful colonization of the A. gigas intestinal tract was observed both by the reduction in total heterotrophic bacteria counts in addition to the increase in E. faecium count in the gut of fish fed with supplemented feed. Lactic acid bacteria are reported to adhere to the intestinal mucosa, probably forming barriers against other bacteria and stimulating the immune system by occupying binding sites (He et al, ; Li et al, ). So, change in the intestinal microbiota of A. gigas promoted by feed with 1 × 10 8 CFU/g (D10 8 ) E. faecium is expected to have been the cause of the improvement in the growth and physiological performance.…”

Intestinal microbiota lipid metabolism varies across rainbow trout (Oncorhynchus mykiss ) phylogeographic divide

“…Among vertebrates it is well documented that gastrointestinal tracts harbour complex and dynamic microbial ecosystems (Nayak 2010;Merrifield et al 2014;Li et al 2018). These diverse microbial communities (i.e.…”

Exogenous enzymes as functional additives in finfish aquaculture

“…In vitro biochemical analysis, lipase could catalyse polyunsaturated fat into polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Hoshino et al, ; Okada & Morrissey ). It was evidenced that both the EPA and DHA supplementations could elevate the expression of zonula occludens 1 (ZO‐1) in colitic rats (Li et al, ) and improve the poor establishment of the beneficial microbiota in the gastrointestinal tract of fish and might promote the proliferation of beneficial microbiota (Li et al, ; Zheng et al, ). In contrast, previous studies have demonstrated that cholesterol‐rich diets could decrease the activities of glutathione peroxidase (GPx) and catalase (CAT) in the liver (Mahfouz and Kummerow, ), and downregulate glutathione S‐transferase ɑ (GSTɑ) and elevate signalling molecule NF‐E2‐related factor 2 (Nrf2) expression in the aortae of rabbits (Bozaykut et al, ).…”

“…Previous reports have shown that the addition of up to 1,000 units/kg of phytase feed could significantly improve the immune response and survival rate of Nile tilapia after being challenged by A. hydrophila (Abo et al, ). In addition, in low‐protein and high‐lipid diets, dietary exogenous lipase improved fish intestinal immune response, which was partly by increasing the acid phosphatase activity and complement component 3 contents, downregulating proinflammatory cytokines gene expression, upregulating antibacterial peptides and anti‐inflammatory cytokine gene expression, which may be partially attributed to regulate nuclear factor‐kB p65 protein inhibitors, κBɑ, IκB intestinal kinase and rapamycin target signalling pathway in fish (Liu et al, ). It is generally accepted that the changes in diet composition have an impact on fish microbiota (Einar et al, ; Li et al, ; Ringo et al, ; Silva et al, ). Recently, more and more studies have been carried out to investigate the effects of exogenous enzymes on the microbiota of fish, and elucidating that the effects of dietary enzymes on intestinal status are both timely and novel.…”