Peer Review #1 of "Systematic evaluation of the gut microbiome of swamp eel (Monopterus albus) by 16S rRNA gene sequencing (v0.2)"

Abstract

Swamp eel (Monopterus albus) is a commercially important farmed species in China. T he dysbiosis and homeostasis of gut microbiota might be associated with swamp eel's diseases pathogenesis and food digestion. The contribution of gut microbiome in fish growth and health is being increasingly recognized. However, little was known about the microbial community in the intestine of swamp eel (Monopterus albus). Methods The intestinal microbiomes of the five distinct gut sections (midgut content and mucosa, hindgut content and mucosa, and stools) of swamp eel were compared by the Illumina MiSeq sequencing of the bacterial 16S rRNA gene sequencing and statistical analysis. Results The results showed that the number of observed OTUs decreased from proximal to distal of intestine. PCoA analysis revealed significant separations among samples from different gut sections. Nevertheless, there were 54 core OTUs shared by all gut sections and 36 out of 54 core OTUs significantly varied in the abundances in different gut sections. Furthermore, we discovered 66 section-specific enriched KEGG pathways. These section-specific enriched microbial taxa (e.g., Bacillus, Lactobacillus) and potential function capacities (e.g., amino acid metabolism, carbohydrate metabolism) might play vital roles in nutrients metabolism, immune modulation, and host-microbe interactions of swamp eel. Conclusions Our results showed that the microbial diversity, composition, and function capacity were varied substantially in different gut sections. The gut section-specific enriched core microbial taxa and function capacities may exert an important role in swamp eel's nutrients metabolism, immune modulation, and host-microbe interactions. This study should provide basic insights into the gut microbiome of swamp eel.