Programming structure and properties of bacterial cellulose via fermentation time and strain: a multivariate...

Bacterial cellulose (BC) is a versatile biopolymer whose properties can be influenced by fermentation conditions. Here, the effects of fermentation time (4-10 days) and microorganism (Komagataeibacter xylinus and K. hansenii) on BC were systematically evaluated. BC membranes were produced by static fermentation in Hestrin-Schramm medium at 30 °C for 4, 6, 8, or 10 days and characterized in terms of production, water absorption, structure, and mechanical properties. K. xylinus exhibited higher productivity, reaching 0.40 g L^-1 day^-1 during the early fermentation period, and produced membranes with substantially higher mechanical performance, with maximum tensile strength of 254.3 ± 3.3 MPa and Young's modulus of 11.09 ± 0.04 GPa after 10 days. Degree of polymerization increased with fermentation time, ranging from 2815 to 3719, while water absorption capacity ranged from 3218 to 3360% for K. xylinus and from 2213 to 3261% for K. hansenii. Thermoporometry and SEM revealed differences in pore organization and fibrillar architecture between strains and fermentation times. Multivariate chemometric analysis further differentiated the samples according to hydration, pore organization, and mechanical properties. Overall, the results demonstrate that fermentation time and microorganism strain can be used as process variables to modulate the structural and functional properties of BC.