A biofilm is an organized, resilient group of microbes where individual cells acquire properties, such as drug resistance, that are distinct from those observed in suspension cultures. Here we describe and analyze the transcriptional network controlling biofilm formation in the pathogenic yeast Candida albicans, whose biofilms are a major source of medical device-associated infections. We have combined genetic screens, genome-wide approaches, and two in vivo animal models to describe a master circuit controlling biofilm formation, composed of six transcription regulators that form a tightly woven network with ~1000 target genes. Evolutionary analysis indicates that the biofilm network has rapidly evolved: genes in the biofilm circuit are significantly weighted towards genes that arose relatively recently with ancient genes being underrepresented. This circuit provides a framework for understanding many aspects of biofilm formation by C. albicans in a mammalian host. It also provides insights into how complex cell behaviors can arise from the evolution of transcription circuits.
Keywords: biofilm, transcriptional regulation, biofilm network, biofilm circuitry, Candida albicans, evolution of transcription circuits, evolution of biofilm formation, evolution of multicellularity