Study on obtaining bacterial cellulose by Komagataeibacter xylinus in co-culture with lactic acid bacteria in whey

The use of acid whey as a medium is an innovative approach to bacterial cellulose (BC) biosynthesis in co-cultures of acetic acid bacteria with lactic acid bacteria. The aim of this study was to evaluate the possibility of obtaining BC in acid whey by co-culturing K. xylinus with selected strains of lactic acid bacteria and comparing the properties of this biopolymer with BC obtained in K. xylinus monoculture. The K. xylinus + Lb. acidophilus co-culture yielded 2.19 g·L^-1 of BC, which was 125% more than the K. xylinus monoculture. Additionally, K. xylinus in co-culture with Lb. acidophilus increased the degradation temperature of BC to 361 °C compared to 303 °C for BC obtained in monoculture. The BC obtained in the co-cultures showed better mechanical properties. BC obtained in co-culture with Lb. delbrueckii showed more than twice the Young's modulus than BC from monoculture. Moreover, strain at break BC from co-culture with Lb. acidophilus and stress at break BC from co-culture with Lb. helveticus were 72% and 54% higher, respectively, than BC obtained from monoculture K. xylinus. In this study, it was shown that conducting acetic-lactic co-cultures increased the efficiency of BC biosynthesis and improved its properties. Moreover, this study has shown that acid whey is a sufficient and complete substrate for obtaining BC. Results presented in this paper indicate new possibilities for the management of this side product. KEY POINTS: • The K. xylinus + Lb. acidophilus co-culture produced 125% more cellulose than the monoculture. • High lactic acid content and low pH of acid whey enhance cellulose biosynthesis. • Acetic acid-lactic acid co-cultures improved the mechanical properties of cellulose.