Enhanced bacterial cellulose production by Komagataeibacter xylinus using agro-derived flour nitrogen sources

Bacterial cellulose (BC) production is limited by the high cost of refined nitrogen sources such as yeast extract and tryptone. While carbon source substitution has been widely studied, approaches for nitrogen replacement remain underexplored. Here, we evaluated cereal and pseudo-cereal flours as low-cost nitrogen alternatives for Komagataeibacter xylinus DSMZ 2325 under static fermentation under static fermentation using two nitrogen substitution strategies: constant total nitrogen (CTN) and constant nitrogen source mass (CNSM). Thirteen flour variants were screened, with maximum BC yields of 3.40 g/L (soy), 3.17 g/L (teff), 2.74 g/L (quinoa), and 1.94 g/L (triticale) under the CTN strategy, in several cases surpassing the modified HS control. Structural analyses confirmed that flour-derived BC retained the defining characteristics of high-quality cellulose, including high crystallinity, robust fibrillar networks, and thermal stability. Soy consistently produced the highest volumetric yields, whereas triticale exhibited the greatest fold-increase compared to the control, highlighting the distinct nutritional and compositional contributions. These results demonstrate that flour-based media provide a viable strategy to reduce production costs while tailoring BC properties through substrate choice. By shifting the focus from carbon to nitrogen optimization, this study introduces a sustainable and scalable approach to bioprocessing using agro-derived raw materials. KEY POINTS: • Flour-based nitrogen sources replace costly yeast extract and tryptone in BC media • Triticale, teff, quinoa, and soy influence BC yield and cellulose fibril formation • Agro-flour substrates offer low-cost, sustainable bacterial cellulose production.