Potential use of pulp and paper solid waste for the bio-production of fumaric acid through submerged and solid state fermentation

Pulp and paper solid waste (PPSW) originating from paper industry, was experimented for the production of fumaric acid (FA) through submerged and solid state fermentation by utilizing the filamentous fungus Rhizopus oryzae 1526. Physicochemical characterization, pH and moisture content analysis of PPSW was carried out. Pre-treatment of PPSW by size reduction resulted in particles of different size ranges (1.7 mm < x ≤ 3.35 mm, 850 μm < x ≤ 1.7 mm, 300 μm < x ≤ 850 μm, 75 μm < x ≤ 300 μm and 33 μm < x ≤ 75 μm). In submerged fermentation with all particle size ranges, a maximum of 23.47 ± 0.70 g/L of FA was obtained with 33 μm < x ≤ 75 μm under the fermentation conditions of 30 °C, 200 rpm, 5% pre-cultured inoculum (v/v) and at 48 h. Viscosity measurement and analysis of by-product of the fermented broths were performed. Microwave-phosphoric acid mediated hydrolysis of 33 μm < x ≤ 75 μm particle size produced hydrolysate with maximum glucose (11.2 ± 0.8 g/L) and xylose (20.22 ± 0.85 g/L) contents. Submerged fermentation with this hydrolysate confirmed the utilization of xylose for both FA production and fungal growth. Solid state fermentation with 75 μm < x ≤ 300 μm particle size resulted in highest FA production (41.45 g/kg dry weight) after 21 days. Scanning electron microscopy revealed the morphological features of the fungus grown on the particles. The results of the present study confirmed the utilization of PPSW as a source of carbon and trace elements by the fungus R. oryzae 1526 and also the bioconversion into FA during fermentation. FA being a high value platform chemical, its bioproduction from the low cost PPSW, is a value addition approach.