Constructing synthetic microbial communities containing Komagataeibacter spp. for kombucha production: Impacts on bioactive compounds, functionality and sensory profiles.

Kombucha is traditional fermented beverage characterized by a symbiotic microbial community (MC), but achieving consistent quality remains a major challenge. This study aims to construct optimized synthetic MCs to enhance bioactivity, functionality and sensorial profiles of tailor-made kombucha. Five recombinational MCs were designed by combining different Komagataeibacter species (K. intermedius (Ki), K. oboediens (Ko), K. rhaeticus (Kr), K. xylinus (Kx), K. saccharivorans (Ks)) with G. potus (Gp), S. davenportii (Sd) and Z. bailii (Zb). The key MCs were screened based on critical sugar-acid metabolism, biofilm formation, growth kinetics and antimicrobial activities. Customized Kx-Gp-Sd-Zb exhibited the highest D-glucuronic acid content (18.5 mg/mL), significantly surpassing spontaneous fermentation (TK, 3.4 mg/mL). Antioxidant assays indicated comparable radical scavenging activity between most MCs and TK. K. intermedius in recombination exhibited superior digestive enzyme inhibitory activity (α-amylase and α-glucosidase), while Ks-Gp-Sd-Zb showed the highest adsorption capacity (46.9 mg/g). Bioaccessibility under simulated gastrointestinal conditions was highest for Kx-Gp-Sd-Zb (80.9%). Kr-Gp-Sd-Zb produced the highest biofilm yield. Safety assessment confirmed no toxicity (100% larval survival) based on Galleria mellonella model. Volatile profiling identified 56 compounds, with Ki-Gp-Sd-Zb exhibiting the highest total content (3421.8 μg/L). Kx-Gp-Sd-Zb contained elevated proportions of phenols, esters, ketones and aldehydes, while 17 key volatiles (rOAV ≥0.1) defined distinct flavor profiles. Electronic and sensory evaluations revealed that three recombinant MCs outperformed TK in acceptability. Sensory evaluation showed tailor-made kombucha with superior aroma scores corresponded precisely with results from flavor and electronic sensory analysis.