Bio-fortification of bacterial cellulose production with black tea extract: Insights into the role of critical amino acids

Bacterial cellulose (BC) holds significant promise for sustainable materials, yet its production efficiency remains a challenge. While nutrient supplementation can enhance yield, the specific role of complex natural extracts, particularly their amino acid components, is not fully understood. This study investigated various tea extracts as bio-fortifiers for BC production by Komagataeibacter xylinus B2–1, focusing on the function of critical free amino acids. Among nine tea extracts representing five fermentation categories, only fully fermented black tea extracts (Jinjunmei and Guangdong Hongyan) significantly increased BC yield (up to 3.730 g L –1 ) without altering its native cellulose I crystalline structure or nanofibrillar morphology. This enhancement was associated with higher glucose-to-BC conversion efficiency rather than greater glucose consumption. Compositional and correlation analyses showed that BC yield was not associated with the total amino acid concentration but was correlated with Pro, Phe, and His. Individual supplementation showed that only His increased BC yield and apparent glucose-to-BC conversion at 10 mg L –1 , and this response plateaued at higher concentrations. Together, these results identify fully fermented black tea extract as a potential bio-fortifier for BC production and support His as a potential tea-derived component contributing to this effect. The study further provides a composition-guided basis for the valorization of low-value tea-processing fractions that retain soluble functional components.