Fungal Biofilms: Inside Out

Abstract

We focus this article on turning a biofilm inside out. The "inside" of the biofilm comprises the individual biofilm-related phenotypes, their environmental drivers and genetic determinants, and the coordination of gene functions through transcriptional regulators. Investigators have viewed the inside of the biofilm through diverse approaches, and this article will attempt to capture the essence of many. The ultimate goal is to connect the inside to the "outside," which we view as biofilm structure, development, pharmacological attributes, and medical impact.

FIGURE 1

Confocal imaging of C. albicans biofilms. (A) Images show the heterogeneity of biofilms at the level of gene expression using a GFP construct fused to the TDH3 promoter that is constitutively expressed throughout the biofilm and an RFP construct fused to the TYE7 promoter showing greater expression at the basal layer of the biofilm, respectively. (B) Images show the phenotypic diversity of biofilms based on the growth medium in RPMI, YPD, and RPMI plus 10% serum, respectively. Biofilms were fixed and imaged using a Zeiss DuoScan confocal microscope. Side view projections were generated by reslicing and then z-projecting the stack using ImageJ software from the National Institutes of Health.

FIGURE 2

Als1 structure. Domains of Als proteins that are discussed in the text are depicted with amino acid coordinates of Als1 indicated.