Decayed fruit waste juice as a sustainable medium for high-yield microbial cellulose production: optimization, characterization and bioactivity studies

In the present study, microbial cellulose (MC) was produced from decayed fruit waste juice as a fermentation medium using a consortium of microbes grown on vegetable and fruit waste as the inoculum. To optimize the MC yield, the central composite design (CCD) of response surface methodology (RSM) was applied. Four factors at five different levels were chosen in the design with a total of 26 experimental runs obtained from the CCD design. The optimal conditions were fruit waste extract (60% v/v), glucose concentration (0.75% w/v), inoculum size (5% v/v), and fermentation time (5 d) which displayed a 2.1-fold increase in MC yield of 21.719 g/L. The MC was characterized using Fourier Transform Infrared Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy, and Thermogravimetric; and compared its properties to cellulose produced through other techniques. The produced MC was examined for its antioxidant properties using cyclic voltammetry (CV) displaying an anodic peak at 1.15 V. Lastly, the antimicrobial activity was tested against four different microbial strains. Among them, MC exhibited a clear zone of 7.661 ± 0.256 cm² against <i>E. coli</i>. The results of this study concluded that decayed fruit waste juice is a sustainable and economical fermentation medium.