Investigating the effect of alkali treatment on physicochemical characteristics of bacterial cellulose synthesized by Komagataeibacter saccharivorans BC-G1

Bacterial Cellulose (BC) has gained significant global interest due to its versatile properties and wide range of industrial applications. However, large-scale BC production faces challenges, particularly in the purification process, where effective removal of bacterial biomass and culture media is critical. Traditional alkali treatments are commonly used, yet the effects of varying alkali concentrations on BC's physicochemical properties are underexplored. Therefore, this study investigates the impact of different sodium hydroxide (NaOH) concentrations (0–8 % w/v) on the solubility, structural, and chemical characteristics of BC produced by Komagataeibacter saccharivorans BC-G1, isolated from rotten grapes. BC was produced under static conditions using four different culture media (HS, M1, M2, and M3), with the highest yield of 104.42 ± 1.48 mg/100 mL in M3 medium after 5 days, compared to 19.2 ± 2.10 mg/100 mL in M2. Physicochemical properties were characterized using FTIR, XRD, DSC, and SEM. FTIR analysis revealed variations in the crystallinity index ranged from 1.08 (standard BC) to 0.98, 1.01, 0.97, and 0.91 in HS, M1, M2, and M3 media, respectively. DSC analysis exhibited crystallization temperatures (Tc) from 83 °C to 112 °C, melting temperatures (Tm) from 293 °C to 445 °C, and glass transition temperatures (Tg) from 28.8 °C to 64.5 °C. Results revealed that alkali treatment disrupted hydrogen bonding within the cellulose structure, leading to changes in bonding patterns and spatial arrangement. High NaOH concentrations induced a transition from cellulose I to cellulose II, highlighting the importance of alkali concentration in determining BC properties.