Protein homeostasis impairment affects phenotypic heterogeneity of biofilms

Biofilms are well organized, cooperating communities of microorganisms encased in a self-produced extracellular matrix, providing resilience against external stress such as antimicrobial agents and host defenses. A hallmark of biofilms is their phenotypic heterogeneity, which enhances the overall growth and survival of the community. In this study, we demonstrate that removing the genes encoding the key molecular chaperones DnaK and trigger factor disrupts protein homeostasis in Bacillus subtilis and leads to the formation of extremely mucoid biofilms with aberrant architecture, compromised structural integrity, and altered phenotypic heterogeneity. These changes include a drastic reduction in the motile subpopulation and an overrepresentation of matrix producers and endospores. Overproduction of poly-γ-glutamic acid contributed crucially to the mucoid phenotype and aberrant biofilm architecture. Elevated temperatures led to protein homeostasis impairment resulting in mucoid and aberrant biofilm phenotypes. Our findings suggest that disruption of protein homeostasis, whether due to the absence of molecular chaperones or environmental factors, constrain biofilm formation. 6 samples. ΔdnaK Δtig (3 biological replicates), wild-type (3 biological replicates)