A fermentative approach towards optimizing directed biosynthesis of fumaric acid by Rhizopus oryzae 1526 utilizing apple industry waste biomass

• First ever report on fumaric acid production from apple industry waste biomass.
• Both liquid and solid waste biomass were utilized by Rhizopus oryzae 1526.
• Morphology of R. oryzae controlled production of fumaric acid and ethanol.
• Optimization of fermentation conditions for enhanced fumaric acid production.
• SEM analysis confirmed growth of R. oryzae on apple solid waste.

The present research account deals with the bioproduction of fumaric acid (FA) from apple pomace ultrafiltration sludge (APUS) and apple pomace (AP) through fermentation. The filamentous fungus Rhizopus oryzae 1526 was used as a biocatalyst and its morphological impact on FA production was analysed in detail. For submerged fermentation, 40 g L−1 of total solids concentration of APUS, pH 6.0, 30 °C, 200 rpm flask shaking speed and 72 h of incubation were found to be optimum for FA production (25.2 ± 1.0 g L−1, 0.350 g (L−1 h−1)). Broth viscosity (cP), residual reducing sugar (g L−1) and ethanol (g L−1) produced as by-product, were also analysed. Plastic trays were used for solid state fermentation and at optimized level of moisture and incubation period, 52 ± 2.67 g FA per kg dry weight of AP was obtained. Changes in the total phenolic content (mg g−1 dry weight of AP) were monitored at regular intervals. Utilization of APUS and AP for the directed synthesis of the high-value platform chemical FA by the fungal strain R. oryzae 1526 was an excellent display of fungal physiological and morphological control over a fermentative product.