Sequential Statistical Optimization of Media Components for the Production of Glucoamylase by Thermophilic Fungus Humicola grisea MTCC 352

Abstract

Glucoamylase is an industrially important enzyme which converts soluble starch into glucose. The media components for the production of glucoamylase from thermophilic fungus Humicola grisea MTCC 352 have been optimized. Eight media components, namely, soluble starch, yeast extract, KH2PO4, K2HPO4, NaCl, CaCl2, MgSO4 ·7H2O, and Vogel's trace elements solution, were first screened for their effect on the production of glucoamylase and only four components (soluble starch, yeast extract, K2HPO4, and MgSO4 ·7H2O) were identified as statistically significant using Plackett-Burman design. It was fitted into a first-order model (R 2 = 0.9859). Steepest ascent method was performed to identify the location of optimum. Central composite design was employed to determine the optimum values (soluble starch: 28.41 g/L, yeast extract: 9.61 g/L, K2HPO4: 2.42 g/L, and MgSO4 ·7H2O: 1.91 g/L). The experimental activity of 12.27 U/mL obtained was close to the predicted activity of 12.15. High R 2 value (0.9397), low PRESS value (9.47), and AARD values (2.07%) indicate the accuracy of the proposed model. The glucoamylase production was found to increase from 4.57 U/mL to 12.27 U/mL, a 2.68-fold enhancement, as compared to the unoptimized medium.

Optimization of biomass and glucoamylase production by Candida famata using response surface methodology

“…Biomass production highly occurred at 0.5 g/L of MgSO 4 , which are comparable to previously reported results (Lagzouli et al, 2007), in same way, effect of MgSO 4 on the production of biomass and glucoamylase by Humicola grisea MTCC 352 (Ramesh and Ramachandra, 2014) and with Thermomucor indicaeseudaticae by Kumar and Satyanarayana (2007).…”

“…As in many other studies, yeast extract helps in the development of mycelial structures with a corresponding higher yield of enzymes (Ramesh and Ramachandra, 2014;Kumar and Satyanarayana, 2007;Arnthong et al, 2015). However, some studies showed that the peptone was the best nitrogen source with Thermomyces lanuginosus, Penicillium fellutanum and Bacillus licheniformis (Kunamneni et al, 2005;Kathiresan and Manivannan, 2006).…”

“…In contrast, maximum α-amylase production by Candida guilliermondii was at 5 g/L of starch (Acourene et al, 2013); whereas, other studies showed maximum glucoamylase activity by thermophilic fungus, Humicola grisea MTCC 352 at 28.41 g/L (Ramesh and Ramachandra, 2014); starch seems to have an "inductive effect" and portrays a significant role in glucoamylase production (Prajapati et al, 2013).…”

Partitioning of thermostable glucoamylase in polyethyleneglycol/salt aqueous two-phase system

“…The commercial production of glucoamylase has been mainly carried out using the genera Aspergillus and Rhizopus [2]. For the manufacture of high-fructose corn syrups, starch needs to be first converted to glucose by high-temperature liquefaction and saccharification [3]. A lot of focus is currently made on the high thermostability of glucoamylase used in the starch processing.…”

“…Moreover, the enzyme is stable when exposed to high temperature for a longer duration. With regard to these advantages, glucoamylase derived from the thermophilic fungus, H. grisea MTCC 352 has been used in the current study [3].…”