Functional genomics of a food-related thermotolerant Acetobacter oryzifermentans strain AAB5: genetic determinants of stress response, CAZyme repertoire, and CRISPR-Cas system.

The thermotolerant Acetobacter oryzifermentans strain AAB5, originally isolated from unripe grape vinegar was identified based on 16S rRNA, recA, and whole-genome sequencing. The genome of AAB5 spans 2,969,314 bp and encodes 2,986 coding sequences (CDSs). Genome annotation revealed numerous genes associated with the strain’s metabolic capacity, thermotolerance, and environmental stress responses. CRISPRCasFinder analysis identified four CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) loci, and comparative genomic analysis showed that, unlike other members of the species, AAB5 harbors a type I-F CRISPR-Cas system. Additionally, a 17.7 kb prophage region was detected in its genome. To gain deeper insights into the fermentative potential of AAB5, we analysed its carbohydrate-active enzyme (CAZyme) genes, which are involved in the synthesis, metabolism, and recognition of complex carbohydrates. The genome encodes 69 CAZymes, predominantly glycosyltransferases (GTs), followed by glycoside hydrolases (GHs). These genes support capabilities such as bacterial cellulose production, biotransformation of waste materials, degradation of phenolic compounds, and utilization of complex carbohydrate sources including starch derivatives, glucans, and trehalose. The genomic architecture of strain AAB5 highlights its metabolic versatility and its potential to serve as a functional industrial culture for traditional vinegar fermentation.