Insights into Agitated Bacterial Cellulose Production with Microbial Consortia and Agro-Industrial Wastes

Abstract

Bacterial cellulose (BC) is emerging as an attractive large-scale polymer due to its superior properties. The dominant static culture for BC fermentation by bacteria or microbial consortium results in low productivity. Agitated culture, as an industrially projected technique, has been widely investigated but exclusively for cellulose-producing bacterial strains. Addressing this concern and evaluating the potential of residues as feedstock, this study highlights the utilization of microbial consortium BA2 and seven agro-industrial wastes including cocoa husks, sugarcane bagasse and others. Remarkably, rice bran (RB) appears as a promising substrate, achieving 2.14 g/L (dry basis) and outperforming the traditional HS medium, evident from a 15-day fermentation. A complex interplay between oxygen availability, glucose consumption and BC yield was revealed; while orbital and magnetic stirring with forced air ventilation (AFV) showed low BC yields and early biomass saturation, 4.07 g/L (dry basis) was targeted by magnetic stirring at 100 rpm from the start using only headspace air. However, beyond controlled operating conditions, mechanical agitation and favorable cellulose adhesion to metal in the stirred tank bioreactor negatively affect BC yield. This pattern uncovers the need for a further approach to the design of bioreactors when the microbial consortium is considered.