Differential expression of Staphylococcus equorum grown alone and in the presence of fungi. Staphylococcus equorum

A specific interaction between the mold Scopulariopsis and S. equorum shifts the composition of the Staphylococcus community from dominance by a strong competitor, S. xylosus, to dominance by a weak competitor, S. equorum. To better understand specific genes and pathways involved with Scopulariopsis stimulation of S. equorum, we used RNA-seq to identify CDS that were up- and down-regulated in the genome of S. equorum in the presence and absence of the mold Scopulariopsis. We compared the effect of Scopulariopsis on the S. equorum transcriptome to the effect of Penicillium on the S. equorum transcriptome to determine why Scopulariopsis had such strong growth promotion effects relative to Penicillium. In the presence of both molds, Methionine biosynthesis and uptake pathways are strongly down-regulated, while Thiamine biosynthesis is up-regulated, suggesting that bacterial-fungal interactions alter the availability of free amino acids and nutrients in cheese environment for both partners. In the presence of Scopulariopsis only, there is a decrease in expression of genes involved with iron acquisition and the production of siderophores, notably the staphyloferrin B operon. Overall design: Staphylococcus equorum was grown on cheese medium alone or with one of two fungal neighbors - a Penicillium spp. or a Scopulariopsis spp.