Characterization of the bacterial community in different parts of the gut of sea cucumber (Apostichopus Japonicus ) and its variation during gut regeneration

Abstract

Bacterial community plays an important role in keeping the health status of the host. A study on the characteristics of gut bacterial community of sea cucumber (Apostichopus japonicus) not only helps improve the current aquaculture model, but promotes healthy and rapid development of the aquaculture industry as well. Therefore, taking pond‐cultured sea cucumber (A. japonicus) as the studying object, the metagenomic and 16S rRNA sequencing technology were used in this study to explore the characteristics of bacterial community in different parts of the gut of sea cucumber, as well as during gut regeneration after evisceration. The results showed that the compositions of bacterial community are different in varying parts of the gut of sea cucumber (A. japonicus). Specifically, bacterial community in the midgut and hindgut are highly similar, showing significantly diversified bacterial species compared to the foregut. GO annotation indicated that the foregut is associated with richer catalytic activity and binding than the midgut and the hindgut. According to the KEGG annotation, metabolism‐related genes are mainly concentrated in the foregut, while genes related to signal transduction and the immune system are mostly annotated in the midgut and hindgut. During the gut regeneration stage, the structure of bacterial community varied greatly in different stage of the regeneration stage, with significant differences between the earlier and later stage. The dominant bacteria in the earlier stage is Rubritalea, and that in the later stage is Arcobacter. Besides, there were Loktanella, Thalassobacter and Phaeobacter in the gut throughout the entire regeneration stage. Cupriavidus, Hellea, HTCC2207, Methylophaga, Methylotenera, Stenotrophomonas and Tenacibaculum were only present in the earlier stage, and gradually disappeared in the later stage due to improving gut functions. The abundance and diversity of bacteria in the gut were higher in the earlier regeneration stage than that in the later stage, with a peak between the 15th and 25th day of the regeneration stage. At 45th day, the abundance and diversity became stable.

Genomic and Metagenomic Insights Into the Microbial Community in the Regenerating Intestine of the Sea Cucumber Apostichopus japonicus

“…In this study, high-throughput sequencing results suggested that bacterial community structures in the intestine of A. japonicus showed significant differences in different regeneration stages. This result is consistent with a previous study (Wang et al, 2018). In the early stage (10 days), a sharp decline in the species richness and diversity of intestinal bacteria was observed, suggesting that the absence of an intestine led to the development of extensive and varied bacterial diversity in the intestine of A. japonicus .…”

“…The intestinal bacterial community structures also changed at the phylum and class levels, and particularly at the genus level in the early stage, and then varied significantly in the later stages (14–18 days). Notably, the community composition recovered to a certain extent at the end of regeneration and was similar to the control (Figure 2 and Supplementary Figure 2), which is consistent with a previous report that bacterial community structure in the intestine of A. japonicus tended to be stable after 21 days of regeneration (Wang et al, 2018).…”

“…Moreover, the intestine regeneration process is accompanied by the reconstruction of the intestinal microbial community. To the best of our knowledge, only one study thus far has addressed the question of variation in the intestinal bacterial composition of A. japonicus during intestine regeneration stages (Wang et al, 2018). This study found that the bacterial community structure in intestine of A. japonicus varied greatly in different regeneration stages, with a significant difference between the earlier and later stages.…”

Distribution of microbiota across different intestinal tract segments of a stranded dwarf minke whale, Balaenoptera acutorostrata

“…Furthermore, molecular fingerprinting technology revealed that bacterial diversity in the canine colon and rectum was significantly higher than the duodenum and jejunum (Suchodolski, Ruaux, Steiner, Fetz, & Williams, 2005). Moreover, bacterial communities in the midgut and hindgut of sea cucumbers had a significantly higher richness and diversity when compared with the foregut (Wang et al, 2018). Taken together, the posterior compartment of the intestinal tract could be more suitable for microbial colonization across diverse animal species.…”

Schizasterid Heart Urchins Host Microorganisms in a Digestive Symbiosis of Mesozoic Origin

“…An increasing number of studies are beginning to shed light on the gut microbiomes found in various echinoderm taxa, among them several deposit-feeding sea cucumber ( Gao et al, 2014 ; Yamazaki et al, 2016 ; Wang et al, 2018 ; Pagán-Jiménez et al, 2019 ; Weigel, 2020 ) and sea urchin species ( Thorsen, 1999 ; Thorsen et al, 2003 ; da Silva et al, 2006 ; Schwob et al, 2020 ). However, most of these analyses focus on microbial organisms found in the main digestive tract, while the present study provides data permitting a comparison between the microbiomes found inside the main gut compartments and a specialized digestive tract derivative.…”