(617c) Interfacial Rheological Properties of Vibrio Cholerae Biofilms

Vibrio cholerae—the causative agent of cholera—is a gram-negative bacterium capable of forming biofilms, which are interface-associated communities of microorganisms surrounded by a self-secreted biopolymer matrix. V. cholerae forms biofilms in its natural aquatic habitat and potentially in vivo, which likely contributes to its survival and infectivity, and the overall severity of cholera outbreaks. To ultimately interfere with the formation of V. cholerae biofilms we require a better understanding of V. cholerae biofilm growth and function. In this study we used interfacial rheology to investigate the elasticity of biofilms growing at the air-liquid interface, called pellicles, to deduce the contribution of different matrix proteins to the biofilm structure. Measurements were performed during pellicle formation on a rugose strain of V. cholerae and its matrix protein mutants. We also used macroscale imaging, electron microscopy, and contact angle measurements to further define pellicle properties and structure. Rheology measurements revealed that the matrix protein Bap1 is uniquely required for maintaining pellicle strength over time, while scanning electron microscopy images show that the Bap1 mutant pellicle microstructure is distinctly different from the rugose pellicle. Additionally, based on contact angle measurements, the Bap1 mutant pellicle is more hydrophilic than the wild-type pellicle. Taken together our results show a connection between the mechanical strength, appearance, and microscale architecture of wild-type and mutant V. cholerae pellicles and suggests that Bap1 may be a critical matrix component to target in biofilm prevention and dispersal.