Methods: Fecal samples were collected from 92 bats in Slovenia, consisting of 12 different species, and the bacterial microbiota was assessed via next generation sequencing of the 16S rRNA gene V4 region.
Results: Sequences were assigned to 28 different phyla, but only Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria accounted for ≥1% of sequences. One phylum (Proteobacteria), one class (Gammaproteobacteria), three orders (Pseudomonadales, Lactobacillales, Bacillales), four families (Enterobacteriaceae, Pseudomonadaceae, Staphylococcaceae, Carnobacteriaceae), and five genera (Pseudomonas, Staphylococcus, Carnobacterium, an unclassified Enterobacteriaceae, Acinetobacter) accounted for 50% of sequences. There were no significant differences in the relative abundances of any phyla between bat species, but various differences were noted at lower taxonomic levels, such as Enterobacteriaceae (P = 0.007, most abundant in M. blythii), Pseudomonadaceae (P = 0.007, most abundant in Rhinolophus hipposideros) and Chlamydiaceae (P = 0.04, most abundant in Myotis myotis). There were significant differences in richness between species in both adults and juveniles/subadults, but there was no impact of sex on any alpha diversity index. When only adults are considered, there were significant differences in community membership between M. blythii and M. emarginatus (P = 0.011), and M. blythii and R. hipposideros (P = 0.004). There were also significant differences in community structure between M. blythii and M. emarginatus (P = 0.025), and M. blythii and R. hipposideros (P = 0.026). When adults of the four main species were compared, 14 OTUs were identified as differentially abundant using LEfSe. Only one difference was identified when comparing R. hipposideros adults and juvenile/subadults, with Klebsiella over-represented in the younger bats.
Conclusions: Bats have a complex and diverse microbiota with a high relative abundance of Proteobacteria. The relevance of this difference is unclear and requires further study. Differences in the microbiota were observed between bat species, perhaps reflecting different diets and environmental exposures.