Effects of process parameters on the antioxidant activity of Phanerochaete chrysosporium bioactive phenolics

Abstract

Oxidative damage to cells and macromolecules is considered to be the cause of several diseases such as coronary heart disease, arthritis, cataractogenesis, various neurodegenerative diseases including alzheimer’s disease, cancer and aging. Several studies have shown that the action of the natural antioxidants at the cellular and molecular level involves scavenging of free radicals. Thus, the search for newer bioactive compounds from the nations biodiversity for better health is a new thrust area in biotechnology. In this study, by using white-rot fungi, Phanerochaete chrysosporium, a submerged fermentation was carried out by using 2 % (w/v) of molasses as the carbon source. The media was suplemented with 2 % (w/v) of potassium dihydrogen phosphate (KH2PO4), 2 % (w/v) manganese sulphate (MnSO4) and 1% (w/v) of ammonium nitrate (NH4NO3) to enhance the strain growth. Six parameters including incubation days, inoculum size, inoculum age ,initial pH, speed agitation and temperature were studied. Incubation time, inoculums size, inoculums age and pH were identified as the most significant variables in antioxidant activity based on DPPH scavenging assay. The highest antioxidant activity, 75.3 % at concentration of 500 mg/L biomass extract was found at 3 days of incubation, 4 % (v/v) of inoculum size, 7 days of inoculum age, at initial pH 6 and 100 rpm and 25 ºC. This result is comparable to the commercial synthetic phenolic antioxidant, BHT ( 68% of inhibition at concentration of at 500 mg/L).