Dietary Correlates of Oral and Gut Microbiota in the Water Monitor Lizard, Varanus salvator (Laurenti, 1768)

Abstract

Numerous studies have demonstrated that food shapes the structure and composition of the host’s oral and gut microbiota. The disorder of oral and gut microbiota may trigger various host diseases. Here, we collected oral and gut samples from wild water monitor lizards (Varanus salvator) and their captive conspecifics fed with bullfrogs, eggs, and depilated chicken, aiming to examine dietary correlates of oral and gut microbiota. We used the 16S rRNA gene sequencing technology to analyze the composition of the microbiota. Proteobacteria and Bacteroidota were the dominant phyla in the oral microbiota, and so were in the gut microbiota. The alpha diversity of microbiota was significantly higher in the gut than in the oral cavity, and the alpha diversity of oral microbiota was higher in captive lizards than in wild conspecifics. Comparing the relative abundance of oral and gut bacteria and their gene functions, differences among different animal groups presumably resulted from human contact in artificial breeding environments and complex food processing. Differences in gene function might be related to the absolute number and/or the taxonomic abundance of oral and gut microorganisms in the wild and the water environment. This study provides not only basic information about the oral and gut microbiota of captive and wild water monitor lizards, but also an inference that feeding on frogs and aquatic products and reducing human exposure help water monitor lizards maintain a microbiota similar to that in the wild environment.

Dietary and Sexual Correlates of Gut Microbiota in the Japa-Nese Gecko, Gekko japonicus (Schlegel, 1836)

“…In this study, mealworm-fed geckos had higher gut microbial community diversity and richness although diet diversity was higher in wild geckos (Figure 2). That food diversity is not associated with gut bacterial alpha diversity in G. japonicus is similar to the findings demonstrated in V. salvator [31], Anser anser [57], and Ochotona curzoniae [58]. However, there are some species such as Gasterosteus aculeatus and Perca fluviatilis [59] and Fejervarya limnocharis [60] where gut microbial alpha diversity is negatively correlated with diet diversity.…”

“…There has been evidence that gut microbial compositions are closely correlated with food ingested by hosts [31] and with their sex [22]. In this study, mealworm-fed geckos had higher gut microbial community diversity and richness although diet diversity was higher in wild geckos (Figure 2).…”

“…At the phylum level, the dominant gut microbes in G. japonicus were Verrucomicrobiota, Bacteroidota, Firmicutes, and Proteobacteria (Figure 1A), This is consistent with what has been observed in leopard geckos (Eublepharis macularius) [32], but differs from the results reported for other reptilian taxa. For example, the dominant gut microbial phyla are Proteobacteria, Bacteroidetes, and Firmicutes in lizards [16,31,46] and snakes [47,48], Bacteroidetes and Firmicutes in turtles [25,49], and Fusobacteria, Proteobacteria, Firmicutes, and Bacteroidetes in crocodiles [50,51]. This indicates that the dominant gut microbial phyla differ among animal taxa.…”

“…Previous studies on reptiles have showed that a given factor may affect the gut microbiota in some species but not in others. For instance, diet shapes gut microbiota in S. crocodilurus [17] but not in Varanus salvator [31]. Compared with other reptile taxa, studies on gut microbiota in geckos have been limited, focusing only on the effects of fasting on gut microbiota in Eublepharis macularius [32,33] and the structure of gut microbiota in Hemidactylus frenatus [34].…”

Dietary and Sexual Correlates of Gut Microbiota in the Japanese Gecko, Gekko japonicus (Schlegel, 1836)

“…Previous studies on reptiles have shown that, for a given factor, it may affect the gut microbiota in some species but not in others. For instance, diet shapes the gut microbiota in S. crocodilurus [ 17 ] but not in the common water monitor Varanus salvator [ 31 ]. Compared with other reptile taxa, studies on gut microbiota in geckos have been limited, focusing only on the effects of fasting on gut microbiota in the common leopard gecko Eublepharis macularius [ 32 , 33 ] and the structure of gut microbiota in the common house gecko Hemidactylus frenatus [ 34 ].…”