Individual Apostichopus japonicus fecal microbiome reveals a link with polyhydroxybutyrate producers in host growth gaps

Abstract

Gut microbiome shapes various aspects of a host’s physiology, but these functions in aquatic animal hosts have yet to be fully investigated. The sea cucumber Apostichopus japonicus Selenka is one such example. The large growth gap in their body size has delayed the development of intensive aquaculture, nevertheless the species is in urgent need of conservation. To understand possible contributions of the gut microbiome to its host’s growth, individual fecal microbiome comparisons were performed. High-throughput 16S rRNA sequencing revealed significantly different microbiota in larger and smaller individuals; Rhodobacterales in particular was the most significantly abundant bacterial group in the larger specimens. Further shotgun metagenome of representative samples revealed a significant abundance of microbiome retaining polyhydroxybutyrate (PHB) metabolism genes in the largest individual. The PHB metabolism reads were potentially derived from Rhodobacterales. These results imply a possible link between microbial PHB producers and potential growth promotion in Deuterostomia marine invertebrates.

Effects of Jerusalem artichoke powder on the growth performance, nonspecific immunity, and gastrointestinal microbiota of sea cucumber

“…Rhodobacterales was more abundant in sea cucumbers treated with 15 g/kg JAP compared to the 10 g/kg JAP treatment (one‐way ANOVA, p < .05; Figure c), which was consistent with the differences in growth rate observed in these two treatment conditions. Previous studies have shown that the relative abundance of Rhodobacterales influences the growth rate of sea cucumbers (Yamazaki et al, ), and our results support this hypothesis. The relative abundance of Flavobacteriales was higher in the Control 2 group compared to the group treated with 15 g/kg JAP ( p < .05).…”

“…Therefore, the relative abundance of Rhodobacterales may impact the growth rate of sea cucumbers. Similar results were observed in a previous study (Yamazaki et al, ). Our results also suggested that the supplementation of 15 g/kg of JAP significantly promoted the growth of the order Rhodobacterales in the gut microbiota while reducing the proportion of potentially harmful bacteria.…”

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

“…Bacterial community is not only an essential component of the gut, but also associated with the life stages such as immune regulation, metabolic absorption, etc (Ellegaard & Engel, 2016;Hegarty, Goopy, Herd & McDorkell, 2007;Yamazaki et al, 2016;Zhou, Hernandezsanabria & Guan, 2009). With a unique ability of gut regeneration, sea cucumber excretes its gut and the respiratory tree from its body via its mouth or cloaca when subjected to external stimulation, and completely regenerates a new digestive system within a very short period of time (Shukalyuk & Dolmatov, 2001).…”

Repeated selective enrichment process of sediment microbiota occurred in sea cucumber guts

“…These enriched bacterial groups, Vibrionales, Alteromonadales and Rhodobacterales, have already been proposed as probiotics candidates positively affecting physiology of A . japonicus in previous study (Chi et al ., ; Yamazaki et al ., ). Additionally, Flavobacteriales could also be a new target for probiotics in sea cucumbers.…”

“…Characterizing sea cucumber gut microbiota through comparison with sediment microbial communities could lead to the development of more effective probiotics for these endangered species. To characterize sea cucumber gut microbiota and to explore potential contribution of their gut microbiota to the host's ecological roles, we performed a spatiotemporally broad assessment of sea cucumber faecal microbiota and sediment microbiota by 16S rRNA gene sequencing analyses without dissection of specimens (Yamazaki et al ., ). Our results show sea cucumber gut microbiota is shaped by selective enrichment process of ingested microbes from sediments, and the repeated process might transform ambient sediment microbial community structures and promote organic matter mineralization.…”