Microbial population dynamics in the faeces of wood-eating loricariid catfishes

Abstract

Significance and Impact of the Study: Although catfishes are not classified as true xylivores, inhabiting their faeces are bacteria that may provide a novel source of cellulolytic enzyme. Based on this first microbiology study, the faeces and thus the gastrointestinal microbiome of Panaque catfishes are an unexplored reservoir of microbial extracts with enhanced polysaccharide transforming enzyme activity. The biomimetical exploitation of this cellulolytic activity in the form of novel enzymes or by applying a mixture of cellulolytic micro-organisms could accomplish a pretreatment to the mechanical production process of nanocellulose fibres, thus could reduce the energy consumption costs significantly. AbstractCatfishes of the genus Panaque are known for their ability to feed on wood and hence to process cellulose fibres in their digestive systems. The paper industry uses cellulose fibres and thus has an interest in exploiting this property biomimetically: it could be employed as a pretreatment to lessen the energy required by the mechanical production stage of manufacturing nanocellulose fibres. Here, we characterize the diet-associated in situ microbial diversity and population dynamic in the faeces of catfish (Panaque sp.) exposed to consecutive diets of pellet food and then wood. Fish faeces samples were collected and investigated by parallel DNA deep amplicon sequencing of the bacterial 16S rRNA SSU for both diet conditions. The most frequently occurring bacterium in the faeces was Cetobacterium sp. The dominant cellulolytic bacterial genera found in ascending relative abundance were as follows: Aeromonas sp., Flavobacterium sp., Bacteroides sp., Pseudomonas sp. and Cellvibrio sp. Diet-associated changes in the faeces microbiome were noted for Flavobacterium sp. Extensive microbial diversity was found in catfish faeces, evidenced using culture-independent molecular techniques. No significant dietassociated effects on the microbiome in terms of biodiversity were observed in the catfish faeces, but diet-associated changes in the microbial population structure were observed.

The variation profile of intestinal microbiota in blunt snout bream (Megalobrama amblycephala) during feeding habit transition

“…However, this genus was not consistently as abundant in the later stages. In previous studies, Cetobacterium , which is capable of inhibiting the growth of other bacterial strains [63], has been found in a variety of freshwater fish species with different trophic categories [56, 64–66]. It is thus likely that Cetobacterium is strongly associated with bacterial colonization during early life stages in our study.…”

The Importance and Benefits of Species

“…Catfish in the genus Panaque, for example, would seem to be an unlikely candidate for better ways to manufacture paper, yet enzymes produced by bacteria in the catfish's digestive tract could serve that end [45] (Figure 1). Biofuels that are more carbon neutral than fossil fuels may have potential in climate change mitigation.…”

Teleost microbiomes: the state of the art in their characterization, manipulation and importance in aquaculture and fisheries

“…It is of considerable interest what role indigenous gut microbiota might play in chitin decomposition. Similarly, the presence of cellulolytic microbial species in the intestines of the wood eating catfish has been probed (Di Maiuta et al, 2013). Such studies will benefit from functional characterization of the bacterial metagenetic repertoire, and teleost alimentary tracts promise rich veins for glycide hydrolase bioprospecting, given the huge variety of different dietary niches they exploit.…”