Fig. 3
Genetic mechanisms driving Serratia proteamaculans dispersal on Mucor networks. a Biplot of mean gene expression data from an RNA-seq experiment of Serratia with and without Mucor networks. Genes that had greater than 2-fold change in expression and deemed significantly different based on a q-value of <0.05 (p-values adjusted for false discovery rate using the Benjamini–Hochberg procedure) were considered significantly increased or decreased in expression. Genes increased in expression are indicated in green, decreased in red, and no change in gray. Three biological replicates were performed for each treatment. b Functional distribution of differentially expressed genes that were annotated with a putative function. Functions were determined based on SEED annotations from RAST. Decreased = significantly decreased expression on Mucor networks. Increased = significantly increased expression on Mucor networks. c Illustration of the Tn5 transposon mutagenesis screen for Serratia dispersal on Mucor. Serratia mutants were arrayed and spotted onto an existing Mucor array growing on PCAMS agar and the resultant plate was screened for changes in the dispersal phenotype. A photograph of an example screen plate is on the right (photo by Scott Chimileski and used with permission). d Dispersal distances along Mucor hyphae of putative Serratia Tn5 mutants compared to the wild-type Serratia, after 7 days of growth. Mutants Tn5_11 and Tn5_54 killed the fungal host and are marked with red “X” over mycelia. One mutant, Tn5_13, displayed limited dispersal along the fungal hyphae. Bars are mean distance from the center of the spot to the bacterial colony edge (±1 standard deviation, n = 5). Dispersal assays were conducted on BHI agar. e Images of the wild-type Serratia, the dispersal deficient Tn5_13, and a killer mutant Tn5_11 with and without Mucor growing on PCAMS agar. The wild-type Serratia disperses to the edge of the hyphae, as outlined in red, while the dispersal deficient Tn5_13 does not disperse as far, as outlined in red. Mutant Tn5_11 completely inhibits the growth of Mucor. See Supplementary Fig. 6 for more genetic and phenotypic data from the selected transposon mutants
