Carbon source-dependent production of bacterial cellulose by Komagataeibacter europaeus FMES: Fermentation performance, structural characterization and transcriptomic insights

Bacterial cellulose (BC), an extracellular polysaccharide produced by microbial fermentation, has attracted increasing interest owing to its unique physicochemical properties and potential applications in the food industry. However, the influence of carbon source on BC productivity, properties, and the associated transcriptional changes remains insufficiently understood. In this study, the effects of eight sole carbon sources on BC production by Komagataeibacter europaeus FMES were systematically evaluated by integrating fermentation performance, structural characterization, and comparative transcriptomic analysis. Among all tested substrates, glycerol exhibited the highest BC productivity (0.198 ± 0.004 g/L/d) and carbon source-to-BC conversion ratio (30.81 ± 2.95%). Furthermore, glycerol-derived BC exhibited favorable properties, including a higher crystallinity (78.08 ± 0.08%) and Young's modulus (4.99 ± 0.65 MPa) than BC produced from the other carbon sources. Transcriptomic analysis identified 345 differentially expressed genes between glycerol- and glucose-grown cells. Genes involved in BC biosynthesis ( bcsA , exoZ , and bcsX ) and gluconeogenesis ( glpK , glpA , fbaA , and glpX ) were significantly upregulated, whereas those associated with glycolysis and the pentose phosphate pathway were downregulated in the glycerol group. These findings provided new insights into carbon source-dependent regulation of BC production and highlighted glycerol as an efficient and promising carbon source for producing BC.