The transcription factor, fixK, plays a central role in carbon source metabolism and cellulose synthesis in Komagataeibacter species

Abstract

Komagataeibacter xylinus ATCC 53582 and K. hansenii ATCC 23769 are model bacterial cellulose producers. This thesis investigated both carbon source utilization and the role that a Crp/Fnr transcription factor, FixK, plays in bacterial cellulose biosynthesis. Extracellular proteins secreted by Komagataeibacter were assayed for degradative activity against plant cell wall compounds. Mutagenesis of fixK, previously associated with cellulose regulation, revealed its role in cellular metabolism. Growth, pH, gluconic acid, and cellulose yield were measured in static and agitated cultures grown in the presence of glucose, fructose or sucrose. BcsZ (formerly CmcAx) was found to be carbon-source regulated. K. hansenii was dependent on fixK for growth in fructose and sucrose, but not in glucose. Mutation of fixK abolished cellulose production in K. hansenii, but limited production in K. xylinus. Altogether, this study improves our understanding of carbon source utilization and bacterial cellulose synthesis in Komagataeibacter species.