Thermo-acid-stable phytase-mediated enhancement of bioethanol production using Colocasia esculenta

Phytase production by the thermophilic mould Thermomyces lanuginosus SSBP was enhanced 8.56-fold in submerged fermentation, which was further improved in fed-batch cultivations. The protein was purified to homogeneity using ammonium sulphate precipitation, Resource Q anion exchange and Superdex gel-filtration chromatography, with an overall purification of 24.7-fold and a yield of 5.16%. The purified 49 kDa protein was optimally active at 55 °C and pH 5.0, and was stable between 50 and 90 °C from pH 3.0-6.0, with a half-life of 138.6 min at 70 °C. It was moderately stimulated by Ba+2 and Mg+2. The enzyme reduced phytate content in Colocasia esculenta starch (from 1.43 mg/g to 0.05 mg/g) that resulted in an improvement in the availability of fermentable sugars with a concomitant reduction in viscosity and 1.59-fold improvement in ethanol production. Thermo-acid-stable phytase from T. lanuginosus SSBP could be of major biotechnological interest, especially due to its robustness and wide applicability.