Histological alterations and microbial ecology of the intestine in gilthead seabream (Sparus aurata L.) fed dietary probiotics and microalgae

Abstract

The effects on histology and microbial ecology in gilthead seabream (Sparus aurata) intestine caused by dietary probiotic and microalgae were studied. Fish were fed non-supplemented (C, control) or supplemented diets with Tetraselmis chuii, Phaeodactylum tricornutum and Bacillus subtilis single or combined (diets T, P, B, BT and BP) for 4 weeks. Curiously, fish fed the experimental diets showed similar morphological alterations when studied by light and electron microscopy and significant signs of intestinal damage were detected. No effect of microalgae or B. subtilis on the intestinal absorptive area was observed, whereas the number of goblet cells and IELs were significantly lower in fish fed the T, P, B and BT diets and T, BT and BP diets, respectively. Interestingly, only the diets containing B. subtilis resulted in a significant reduction of microvilli height. Alterations such as wide intercellular spaces and large vacuoles in enterocytes were observed in fish fed T, B, BT, BT and P in lesser degrees. These observations demonstrate that fish fed experimental diets presented different signs of oedema and inflammation that could compromise their body homeostasis. Moreover, the experimental diets cause important alterations in the intestinal microbiota by a significant decrease in bacterial diversity, as demonstrated by the fall in specific richness, Shannon and range-weighted richness indices. To our knowledge, this is the first in vivo study regarding the implications of the use of probiotics in combination with immunostimulants on fish intestinal morphology and microbiota. More morphofunctional studies are needed in order to correlate the nutritional and immune aspects of fish gut.

Nutritional impacts on fish mucosa: immunostimulants, pre- and probiotics

“…When hostderived Lactobacillus delbrueckii ssp. In addition, substantial increments on goblet cell population and structural changes in villi as typified by increase in length and fold length were also noted in the mentioned fish species as well as in rainbow trout (Standen et al, 2012;Cerezuela et al, 2012a;Merrifield et al, 2010). This was the first study in fish to have reported probiotic-induced changes on T-cell activity (Picchietti et al, 2009).…”

Probiotic bacteria may prevent haemorrhagic septicaemia by maturing intestinal host defences in Brazilian native surubins

“…Similar results using fish fed supplemented diet with probiotic were found in previous studies in gilthead seabream Sparus aurata (Cerezuela et al . ) and L. rhamnosus used in Nile tilapia feeding (Pirarat et al . ).…”

Effects of low‐level dietary microalgae supplementation on the distal intestinal microbiome of farmed rainbow trout Oncorhynchus mykiss (Walbaum)

“…It has been widely reported that the gut microbiome of aquatic animals is responsible for the digestion of algal cells and the production of both amino acids and short-chain fatty acids, in addition to the secretion of compounds that can inhibit the growth of potential pathogens (Austin 2006;Nayak 2010;Clements, Angert, Montgomery & Choat 2014;Ghanbari, Kneifel & Domig 2015). Research concerning the impact of microalgae on the structure of the intestinal microbiome, however, is limited and has hitherto primarily focused on wild herbivorous fish species that consume algal substrates in their natural habitat (Choat & Clements 1998;Clements, Pasch, Moran and Turner 2007;Ward, Steven, Penn, Methe & Detrich 2009;Smriga, Sandin & Azam 2010) with only a single study examining farmed fish species (Cerezuela, Fumanal, Tapia-Paniagua, Meseguer, Morinigo & Esteban 2012). Conflicting results have been reported in these studies, with some authors observing increases and others noting decreases in the microbial diversity within the intestinal tracts of fish with diets rich in microalgae.…”