Quantitative transcriptome analysis of C. albicans biofilms grown in high and low carbon dioxide conditions.

C. albicans is a dimorphic yeast which can switch from budding yeast and to hyphal forms and this property is essential for biofilm establishment and maturation. C. albicans undergoes this yeast-to-hyphal switch in response to high CO2. The purpose of this study is to use RNA-seq to investigate pathways whose genes are differentially expressed when C. albicans biofilms are grown in a physiologically relevant elevated (5%) CO2 environment compared to a low/atmospheric (0.03%) CO2 environment. We report that in C.albicans biofilms grown under 5% CO2 conditions, genes controlled by core biofilm regulatory transcription factors such as Brg1, Efg1, Ndt80, and Bcr1 are overall expressed at significantly higher levels compared to those grown in 0.03% CO2 conditions. We find that genes encoding glucose and amino acid transporters, as well as genes previously found to be involved in the response to Ketoconazole treatment, are significantly upregulated in 5% CO2 C. albicans biofilms. Overall, these data suggest a high CO2 environment enhances biofilm formation of C. albicans and may also increase antifungal tolerance of such biofilms. Overall design: Analysis of mRNA profiles from 48hr old C. albicans (strain CAI-4) biofilms grown in 0.03% and 5% CO2 environments on silicone surfaces. RNA was extracted from 3 biological replicates for each CO2 environment.