Comparative Analysis of Gut Microbial Community Structure of Three Tropical Sea Cucumber Species

Abstract

Based on 16S rRNA gene high-throughput sequencing technology, the microbial community structure in the gut of three tropical sea cucumber species, Holothuria atra, Stichopus chloronotus, and S. monotuberculatus, and their habitat sediments were analyzed. The OTUs in the gut contents of S. monotuberculatus, S. chloronotus, H. atra, and their sediments were 2489 ± 447, 1912 ± 235, 1628 ± 150, and 4162 ± 94, respectively. According to alpha diversity analysis (Ace, Chao1, Shannon, Simpson), the richness and diversity of microflora in the gut of all three sea cucumber species were significantly lower than that in sediments (p < 0.01). Anosim analysis showed that the intra-group differences were less than the inter-group differences (R > 0), and the microbial community composition of the sediment was distinctly different from those of three sea cucumber species (p < 0.05). UPGMA tree and Anosim analysis also revealed that the gut microbial communities of H. atra and S. chloronotus were more similar than that of S. monotuberculatus. Proteobacteria was the predominant phylum in all samples, and there was no significant difference in relative abundance among all groups. Actinobacteria was also a dominant phylum, and the relative abundance in S. chloronotus was significantly higher than that in other samples (p < 0.05). Potential probiotics and sequences related to Lactobacillus and Pseudomonas that may be developed for sea cucumber culture were also found in the study. It is speculated that the main reason for the difference in microbial communities between gut microbiota and environmental sediments may be the unique and quite different environment in the digestive tract of sea cucumbers. Whereas, the differences in gut microbiota among the three sea cucumber species were caused by selective feeding. These findings may provide basic data for tropical sea cucumber gut microflora studies and assist in the sea ranching and aquaculture development of the tropical sea cucumber species.

Comparative analysis of the gut bacteria and fungi in migratory demoiselle cranes (Grus virgo) and common cranes (Grus grus) in the Yellow River Wetland, China

“…At the phylum level, the bacterial phylum with the highest abundance in demoiselle and common crane samples was Firmicutes. This is consistent with the results for gut bacteria in captive common and demoiselle cranes (Wang, 2022). Research has indicated that Firmicutes are more abundant in herbivorous animals (Wang et al, 2022), and their main function is to break down cellulose into volatile fatty acids that can be assimilated by the host, increase nutrient utilization, regulate T cells to strengthen host immunity, inhibit intestinal inflammation, and maintain the ecological balance of the gut microbiota (Fernando et al, 2010;Guan et al, 2017).…”

“…In the present study, 16S rRNA and ITS high-throughput sequencing was performed to analyze the diversity and composition of gut bacteria and fungi of common and demoiselle cranes migrating to the Yellow River Wetland. The results suggested that the α-diversity of the gut microbial of demoiselle cranes was remarkably higher than that of common cranes, and this differed from findings presented in another study analyzing the gut microbial diversity of five species of captive cranes (Wang, 2022). Studies have demonstrated that a more diverse food composition results in a higher diversity and richness of the host gut microbiota (Lau et al, 2018).…”

“…Common cranes feed more on the stems, leaves, and fruits of plants. The diet of demoiselle cranes is relatively broad, and they eat both animal foods such as insects, fish, and shrimp and plant foods such as tender buds and leaves (Wang, 2022). Based on their food consumption pattern, the higher Chao1 diversity of the gut microbial of demoiselle cranes may be related to the different feeding habits of these two cranes.…”

Comparative Analysis of Gut Bacterial Community Composition in Two Tropical Economic Sea Cucumbers under Different Seasons of Artificial Environment

“…Whether in the dry season or the wet season, Proteobacteria had the highest abundance in all samples. These bacteria, generally Gram-negative, are widely distributed and diverse in shape, which are the dominant phylum identified in the gut contents of numerous marine invertebrates [26][27][28][29][30]. The amount of research on gut microbes of A. japonicus is most frequent among Holothuroidea species, and Proteobacteria always occupy the dominant position [10,31,32].…”

“…We also compared the results of current research with previous studies that focused on the dominant gut bacterial community of the same sea cucumber species in the wild environment. Plotieau et al (2013) collected H. scabra from the intertidal zone at different seasons to explore the bacterial diversity of sediments transiting through the gut of these species, and Wang et al (2023) analyzed the gut microbial community structure of S. monotuberculatus with other two sea cucumber species in the wet season [30,39]. The results showed that, at the phylum level, Proteobacteria was still the dominant gut bacterial community even in a natural environment.…”