Solid-State Fermentation of Agroindustrial Residues for Glucoamylase Production from Endophytic Fungi Penicillium javanicum of Solanum tuberosum L.

Glucoamylase production has been evaluated under solid-state fermentation of agro-industrial residues including groundnut shell, corncob, corn stover, sugarcane bagasse, wheat straw, barely straw and rice straw as renewable cheap substrates by different 14 endophytic fungal species. Among them the endophytic fungi Penicillium javanicum obtained from the root of Solanum tuberosum L. showed the maximum yield of glucoamylase using groundnut shell as solid substrate (289.23 ± 0.80 U/gds). Under the optimized production parameters in solid state fermentation process (250 mL Erlenmeyer flask containing 20 grams groundnut shell supplemented with 30% soya waste as an inexpensive, eco-friendly way of enzyme production sieved to 1mm, moistened to 55% initial moisture content with potato process wastewater, pH 5.0, inoculum intense 2 × 108 spore and incubated at 30°C for 5 days fermentation period), a fourfold increase (4.19-fold) in glucoamylase production was occurred. In our study there was a strong relation between the enzyme secretion and the trophophase. The purified enzyme exhibited specific activity 81.60 and 237. 24 U/mg with enzyme recovery equal to 51.11 and 22.14% and purification fold 2.2 and 6.39-fold after the precipitation with (NH4)2SO4 and gel fractionation on sephadex G-100, respectively with maximum activity at 40-50°C and pH 5 and it was stable and retained 100% of its activity at temperature up to 60°C along with pH 5–7. The enzyme was not metallo enzyme due to EDTA and EGTA at 50 mM had no effect on glucoamylase activity but it was considered as a serine protease due to it lost 68 and 92% of its activity the serine protease inhibitor paramethyl sulfonyl fluoride (PMSF) at 10 and 50 mM, respectively.