Transcriptomic analyses of Staphylococcus epidermidis in mixed-species biofilms with Candida albicans

To explain enhanced biofilm formation and increased dissemination of S. epidermidis in mixed-species biofilms, microarrays were used to explore differential gene expression of S. epidermidis in mixed-species biofilms. One sample from single species biofilm (S1) and mixed-species biofilm (SC2) were excluded from analyses for outliers. We observed upregulation (2.7%) and down regulation (6%) of S. epidermidis genes in mixed-species biofilms. Autolysis repressors lrgA and lrgB were down regulated 36-fold and 27-fold respectively and was associated with increased eDNA possibly due to enhanced autolysis in mixed-species biofilms. These data suggest that bacterial autolysis and release of eDNA in the biofilm matrix may be responsible for enhancement and dissemination of mixed-species biofilms of S. epidermidis and C. albicans. Staphylococcal gene expression in mixed-species biofilms with Candida and in single species biofilms of S. epidermidis were analyzed. The experiment was repeated thrice on 3 different days (3 biological replicates each for single species biofilms of S. epidermidis and mixed-species biofilms). Only 2 biological replicates were analyzed and one biological replicate was not analyzed (S1 and SC1 - raw data files are provided on the Series record). Single species biofilms of S. epidermidis (strain 1457) and C. albicans (strain 32354) and mixed-species biofilms were formed on 6-well tissue culture plates. Five ml of organism suspensions (O.D. 0.3, S. epidermidis 107 CFU/ml or C. albicans 105 CFU/ml) or 2.5 ml each for mixed-species biofilms for 24 hr. RNA was harvested from single species and mixed-species biofilms.