Fig 1.
Conceptual model representing potential responses and interpretations of microbial community structure and function in the presence of a pathogen.
Fig 2.
Effects of treatment on bullfrogs’ Bd infection intensity at day 7 (a) and proportional growth at day 42 (b). Error bars represent standard error. The significant relationship between individual bullfrogs’ Bd infection intensity at day 7 and proportional growth at day 42, the end of the experiment (c).
Fig 3.
NMDS ordinations based on weighted UniFrac distance matrices (a,b) and Sorensen dissimilarity matrices (c,d) representing differences among microbiota manipulations in microbial community structure and metabolite profiles, respectively, of frogs exposed (a,c) and unexposed (b,d) to Bd one week after initial exposure to Bd.
There were differences in microbial community structure and metabolite profiles among microbiota manipulation only with Bd exposure.
Table 1.
Summary of PERMANOVA results comparing microbial community structure (beta diversity of OTUs, UniFrac distance matrices) and function (Metabolite profiles, Sorensen dissimilarity matrices) across microbiota manipulations of frogs exposed and not exposed to Bd.
Visualizations of these comparisons can be seen in Fig 3.
Table 2.
List of 37 OTUs that differed significantly in relative abundance among microbiota manipulation treatments (antibiotics, augmented with J. lividum, and unmanipulated) 7 days after exposure to Bd, based on a Kruskal-Wallis test with Bonferroni corrected P values.
Taxonomy includes the phylum and the lowest classification that could be defined for each OTU. Phyla are abbreviated as follows: Act = Actinobacteria, Bac = Bacteroidetes, Pro = Proteobacteria. OTUs are ranked in order of relative abundance in the unmanipulated treatment. The Comamonadaceae OTU that was positively correlated with frog growth among Bd-exposed frogs is bolded. Representative 16S rRNA gene sequences for these 37 OTUs can be found in S1 Text.
Fig 4.
Effects of Bd exposure (white bars = No exposure to Bd; grey bars = Exposure to Bd) and bacterial treatment (normal, antibiotics, and augmented with J. lividum) on OTU richness (a), phylogenetic diversity (b), and relative abundance of the probiotic J. lividum (c) on bullfrog skin one week following exposure to Bd (day 7).
Error bars represent standard error. * represent significant differences among treatments.
Fig 5.
Correlations between OTU richness (a,b) or phylogenetic diversity (c,d) at day 7 and proportional growth at day 42, with (a,c) and without (b,d) exposure to Bd.