Early-life intestinal microbiome in Trachemys scripta elegans analyzed using 16S rRNA sequencing

Abstract

During the early-life period, the hatchlings of red-eared slider turtles (Trachemys scripta elegans) rely on their own post-hatching internal yolk for several days before beginning to feed. The gut microbiome is critical for the adaptation of organisms to new environments, but, to date, how the microbiome taxa are assembled during early life of the turtle is unknown. In this study, the intestinal microbiome of red-eared slider hatchlings (fed on commercial particle food) was systematically analyzed at four different growth stages (0 d, 10 d, 20 d, 30 d) by a high-throughput sequencing approach. Results showed that the dominant phyla were Firmicutes (58.23%) and Proteobacteria (41.42%) at 0-day, Firmicutes (92.94%) at 10-day, Firmicutes (67.08%) and Bacteroidetes (27.17%) at 20-day, and Firmicutes (56.46%), Bacteroidetes (22.55%) and Proteobacteria (20.66%) at 30-day post-hatching. Members of the Bacteroidaceae family were absent in 0-day and 10-day turtles, but dominated in 20-day and 30-day turtles. The abundance of Clostridium also showed the highest value in 10-day turtles. The richness of the intestinal microbiomes was lower at 0-day and 30-day than that at 10-day and 20-day, while the diversity was higher at 10-day and 30-day than that at 0-day and 20-day. The results endowed the turtles with an ability to enhance their tolerance to the environment.

Comparative Analysis of the Fecal Microbiota of Wild and Captive Beal’s Eyed Turtle (Sacalia bealei) by 16S rRNA Gene Sequencing

“…Our work is the first on an Asian freshwater turtle species (family Geoemydidae). Our results for wild S. bealei at the phylum level was similar to one species (Graptemys psesudogeographica) (Butterfield, 2019) dominated by Proteobacteria, while different from other species (Chrysemys picta and Trachemys scripta elegans) (Fugate et al, 2019;Peng et al, 2020) dominated by Firmicutes. The limited amount of gut microbiota data for turtles and especially freshwater turtles prevents us from making any generalizations, but we hope that future studies will help us understand the host-microbiota relationship in turtles.…”

“…A trend first found in humans, individuals with plant-based diets have gut microbiota dominated by taxa in the phylum Firmicutes that metabolize plant polysaccharides and degrade cellulose into volatile fatty acids, while animal-based diets are dominated by taxa in the phyla Proteobacteria that are bile tolerant (David et al, 2014). This pattern was also seen in turtle studies, with herbivorous species having gut microbiota dominated by Firmicutes (Gaillard, 2014;Modica, 2016;Fugate et al, 2019;Peng et al, 2020), while carnivorous and omnivorous species had gut microbiotas dominated by Bacteroidetes (Biagi et al, 2018;Bloodgood et al, 2020). In particular, Bloodgood et al (2020) showed that gut microbial diversity has the ability to change in relation to diet; when herbivorous green sea turtles (Chelonia mydas) were given an omnivorous diet (seafood + vegetables) in captivity, their gut microbiota shifted from being dominated by Firmicutes to Bacteriodetes.…”

“…Studies of turtle gut microbial diversity have found influences of diet (Modica, 2016;Bloodgood et al, 2020), geography (Butterfield, 2019), and ontogeny (Yuan et al, 2015;Peng et al, 2020). For the influence of diet, the pattern in turtles was similar to that seen in humans; individuals with plant-based diets had gut microbiota dominated by Firmicutes, while individuals with animal-based diets had gut microbiota dominated by Bacteroidetes (David et al, 2014).…”

“…The gut microbiota work on freshwater turtles has only covered a few North American species (family Emydidae) (Butterfield, 2019;Fugate et al, 2019;Peng et al, 2020). Our work is the first on an Asian freshwater turtle species (family Geoemydidae).…”

“…Turtles are particularly poorly represented in the gut microbiota literature, but the available studies suggest the gut microbiota is influenced by diet, geography, and ontogeny. For diet, turtle groups with different ecologies (sea turtles, freshwater turtles, tortoises) show a similar trend; species with plant-based diets had gut microbiota dominated by the bacterial phylum Firmicutes (Gaillard, 2014;Modica, 2016;Fugate et al, 2019;Peng et al, 2020), while species with animal-based diets were dominated by Bacterioidetes (Biagi et al, 2018;Bloodgood et al, 2020). In this study, we focus on the freshwater Beal's eyed turtle (Sacalia bealei) from southern China (Anhui, Fujian, Guangdong, Guangxi, Guizhou, and Jiangxi Provinces, and Hong Kong) (Shi et al, 2008).…”