Isolation and characterization of Acetobacter tropicalis from kombucha as an acid-tolerant, high-yield producer of bacterial cellulose.

This work describes the isolation and characterization of a bacterial cellulose (BC)-producing strain from Colombian kombucha, identified as Acetobacter tropicalis 70-1. The isolate was distinguished by its ability to form a polysaccharide pellicle under acidic conditions, reaching a thickness of 12 mm by day 20. Molecular identification through 16S rRNA sequencing showed 99% identity with reference A. tropicalis strains. The bacterium displayed typical phenotypic traits of the genus, including catalase activity, negative oxidase response, and ethanol oxidation to CO₂. Under static culture, the highest BC yield (14.2 g/L) was achieved at pH 3. FTIR spectra confirmed hydroxyl, carbonyl, and glycosidic groups, while XRD showed diffraction peaks at 2θ ≈ 14.6°, 16.9°, 22.8°, and 34.7°, consistent with cellulose Iα and a high crystallinity index. Thermal analysis (TGA/DTG) indicated degradation patterns comparable to pure BC, and scanning electron microscopy (SEM) showed a compact, interconnected fibrillar network. SEM-based morphometry, supported by diameter distribution analysis across independent micrographs, indicated a consistent submicron fiber diameter profile. Altogether, the results demonstrate the acidophilic nature and structural quality of BC produced by A. tropicalis 70-1, supporting its application-relevant potential for biomedical membranes and biodegradable packaging, subject to biocompatibility, mechanical, and barrier validation. Furthermore, this study underscores microbial bioprospecting in fermented beverages as a sustainable approach for identifying naturally bacterial cellulose producers.