Enhanced Fumaric Acid Production from Brewery Wastewater and Insight into the Morphology of Rhizopus oryzae 1526

Abstract

The present work explores brewery wastewater as a novel substrate for fumaric acid production employing the filamentous fungal strain Rhizopus oryzae 1526 through submerged fermentation. The effects of different parameters such as substrate total solid concentrations, fermentation pH, incubation temperature, flask shaking speed, and inoculum size on the fungal morphologies were investigated. Different morphological forms (mycelium clumps, suspended mycelium, and solid/hairy pellets) of R. oryzae 1526 were obtained at different applied fermentation pH, incubation temperature, flask shaking speed, and inoculum size. Among all the obtained morphologies, pellet morphology was found to be the most favorable for enhanced production of fumaric acid for different studied parameters. Scanning electron microscopic investigation was done to reveal the detailed morphologies of the pellets formed under all optimized conditions. With all the optimized growth conditions (pH 6, 25 °C, 200 rpm, 5% (v/v) inoculum size, 25 g/L total solid concentration, and pellet diameter of 0.465 ± 0.04 mm), the highest concentration of fumaric acid achieved was 31.3 ± 2.77 g/L. The results demonstrated that brewery wastewater could be used as a good substrate for the fungal strain R. oryzae 1526 in submerged fermentation for the production of fumaric acid.