The autochthonous microbiota of the freshwater omnivores jundiá (Rhamdia quelen) and tilapia (Oreochromis niloticus) and the effect of dietary carbohydrates

Abstract

Previous studies have shown that the gut microbiota of fish differs depending on host feeding habits and these populations may also be influenced by dietary ingredients. In this study, the bacterial populations of the intestinal tract of the opportunistic omnivore jundiá Rhamdia quelen and the typical omnivore tilapia Oreochromis niloticus were investigated in two experiments. In experiment I, the levels of amylolytic, cellulolytic, lipolytic, proteolytic and total culturable bacteria were compared in the proximal, mid and distal intestine using selective agar. Higher levels of amylolytic, cellulolytic, lipolytic, proteolytic and total culturable bacteria were observed in the tilapia than jundiá, in all intestinal regions. Jundiá contained higher levels of proteolytic bacteria and lipid digesting bacteria in the distal intestinal portion as compared with the mid intestine; both fish species also presented more amylolytic bacteria in the distal intestine. In experiment II, the amylolytic intestinal microbiota between the two species was compared after administration of diets containing different carbohydrate sources. Jundiá fed broken rice presented higher total culturable bacterial levels; however, dietary cassava bagasse and ground corn significantly elevated the population of amylolytic bacteria in tilapia (P > 0.05). PCR‐DGGE was also used to assess the bacterial communities in experiment II. A Cetobacterium spp. was detected in jundiá fed diets containing broken rice, and tilapia fed cassava bagasse, dextrin, broken rice and ground corn. Microbial differentiation was further demonstrated between jundiá and tilapia, because an uncultured bacterium was unique in tilapia and an uncultured spirochete was observed only in jundiá; the presence of these bacterial species was also influenced by dietary carbohydrate sources.

Intestinal microbiota in rainbow trout,Oncorhynchus mykiss, fed diets with different levels of fish-based and plant ingredients: A correlative approach with some plasma metabolites

“…The presence of Cetobacterium sp. in the intestine of tilapia and jundiá was influenced by dietary carbohydrate sources (Pedrotti et al., ). In the present experiment, there was no such effect of the plant‐based ingredients, except on Cetobacterium sp.…”

Effect of β-Glucans in Diets on Growth, Survival, Digestive Enzyme Activity, and Immune System and Intestinal Barrier Gene Expression for Tropical Gar (Atractosteus tropicus) Juveniles

“…Therefore, it may be possible that the high amounts of β-glucans used in the present study (2.0%) could have contributed to a saturation of amino acid transporters that could promote a possible inhibition or inactivation of the digestive enzymes, as well as the possible alteration of the gut microbiota; however, there are few studies that evaluate what effects an excess of β-glucans has on the digestive capacity of fish [41]. The different effect β-glucans have on alkaline proteases, trypsin, and chymotrypsin ratio deserves further attention, as well as the potential role of this prebiotic on enhancing the digestive function in fish [42].…”

Strategies to modulate the intestinal microbiota of Tilapia (Oreochromis sp.) in aquaculture: a review

“…They determined that the diets altered the composition of the bacterial populations present in the intestine of fish and the changes were also dependent on the species of fish (Pedrotti et al . ). This is an important first step in the investigation of the effect of feed ingredients on the intestinal microbiota of tilapia and should be used as a model for optimizing diets containing alternative feed ingredients.…”