Glucose, Cyc8p and Tup1p regulate biofilm formation and dispersal in wild Saccharomyces cerevisiae

Abstract

Saccharomyces cerevisiae is a mainly beneficial yeast, widely used in the food industry. However, there is growing evidence of its potential pathogenicity, leading to fungemia and invasive infections. The medical impact of yeast pathogens depends on formation of biofilms: multicellular structures, protected from the environment. Cell adhesion is a prerequisite of biofilm formation. We investigated the adherence of wild and genetically modified S. cerevisiae strains, formation of solid-liquid interface biofilms and associated regulation. Planktonic and static cells of wild strain BRF adhered and formed biofilms in glucose-free medium. Tup1p and Cyc8p were key positive and negative regulators, respectively. Glucose caused increased Cyc8p levels and blocked cell adhesion. Even low glucose levels, comparable with levels in the blood, allowed biofilm dispersal and release of planktonic cells. Cyc8p could thus modulate cell adhesion in different niches, dependently on environmental glucose level, e.g., high-glucose blood versus low-glucose tissues in host organisms.

Spatially structured yeast communities: Understanding structure formation and regulation with omics tools

“…Furthermore, the ability to form biofilms is affected differently by growth conditions in different yeast species/strains. For example, some natural strains of S. cerevisiae , as well as yeast strains belonging to important opportunistic pathogens such as Candida albicans , C. glabrata , C. tropicalis , C. dubliniensis , and C. parapsilosis , produce biofilms, but the conditions of biofilm formation and biofilm structure can vary considerably [27] , [28] , [29] , [30] . As with bacteria, biofilm formation is usually associated with increased virulence of the yeast pathogen.…”

“…The same is true for target genes, where current omics-based knowledge is insufficient to distinguish functions directly related to biofilm formation from metabolic functions, whose regulation also differs in different yeasts and conditions. For example, the conditions (medium composition) used to compare the 4 yeast species of the CTG clade did not lead to biofilm formation in C. glabrata and S. cerevisiae (not belonging to the CTG clade) [28] , which form a structured biofilm under different conditions [27] , [30] , [61] .…”

“…The natural S. cerevisiae strains that form colony biofilms (see above) also have the ability to adhere to a polystyrene surface and form a structured biofilm ( Fig. 1 ) [30] . Apart from Flo11p, which is essential for cell adhesion and biofilm formation on polystyrene [62] , [63] , [64] , little is known about metabolic changes and regulation behind the formation of these biofilms.…”

“…B, cross sections of the structures visualized by 2-photon confocal microscopy (colony and colony biofilm) or wide-field microscopy (biofilm). Colonies: green, U-layer of cells expressing Cit3p-GFP; red, L-cells visualized as cell autofluorescence (adapted from [22] ); colony biofilm: Rpa19p-GFP level differs in aerial and root parts (adapted from [7] ); vertical structure of SLI biofilm (adapted from [30] ). Dashed lines, surface of agar (white), polystyrene surface (black).…”

Yeast biofilm in food realms: occurrence and control

“…Similarly, glucose starvation increases biofilm formation and FLO11 expression through the cAMP–PKA and SNF1 pathways (Livas et al 2011 ; Bojsen et al 2012 ). Van Nguyen et al ( 2020 ) reported that the inhibition of biofilm formation at high glucose concentration is mediated by increased Cyc8p-mediated FLO11 repression. Zara et al ( 2010 ) suggested that biofilm formation requires an energy input provided by reduced carbon sources.…”