Changes in the Gut Microbiota Diversity of Brown Frogs (Rana Dybowskii) After Local Antimicrobial Therapy

Abstract

Background: Amphibians frequently receive an antibiotic bath after feedlot placement to control bacterial diseases. The potential collateral effect of these antibiotics on the frog microbiota is largely unknown. Antibiotics are frequently employed to examine the role of the gut microbiota. Existing research relies mainly on oral antibiotics, but knowledge regarding the effects of antibiotics on the gut microbiota through a bath or local antimicrobial therapies is limited. Results: The gut microbiota of gentamicin, recovered, and control Rana dybowskii groups were compared by Illumina high-throughput sequencing, and the functional profiles were analysed using a phylogenetic investigation of communities by the reconstruction of unobserved states (PICRUSt). Furthermore, the relationship between gut microbiota structures and forecast function compositions was determined. The results showed that the alpha diversity indices were significantly reduced by the gentamicin bath, which significantly changed the composition of the gut microbiota. After 7 days, the gut microbiota was still similar to that during the gentamicin bath. Forty-four indicator species were selected at the genus level, namely, 42 species indicating the control group and 2 species indicating the gentamicin and recovery groups. Potential pathogenic bacteria belonging to Aeromonas, Citrobacter, and Chryseobacterium significantly decreased after the gentamicin bath. The community similarity assays did not show an obvious discrepancy in the functional composition between the gentamicin and control frogs, indicating that the functions of the gut bacterial community were highly redundant. Conclusions: The gentamicin bath significantly reduced the alpha diversity of the gut microbiota of R. dybowskii. Gentamicin significantly changed the structure of the gut microbiota, and the gut microbiotas exhibited weak resilience and did not totally recover after seven days. The gentamicin bath did not change the functional composition of the gut microbiota of R. dybowskii, and there was no significant correlation between the composition of the gut microbiota and the functional composition, illustrating the high intestinal functional redundancy of the frog gut bacterial community. This work offers basic data for upcoming research, including the establishment of the amphibian gut microbiota and local antibiotic administration, and has important implications for aquaculture management and amphibian conservation.