Studies on Kinetic Properties of Aspergillus Producing Peroxidase from Petroleum Hydrocarbon Spilled Soil

Abstract

Peroxidases production was carried out from Aspergillus tamari isolated from petroleum hydrocarbon spilled soil. Physicochemical properties of the respective soil showed pH of 4.45 and 6.5 for soils from point 1 and II respectively and higher conductivity of 613 and 1013 (Ω -1 Cm -1) , respectively when compared with the control sample. Dissolved mineral of Cl - , SO 4 , K, Ca, Mg in the respective soil samples from the petroleum spilled sites were significantly high when compared with the control experiment except for soil sample I which showed a relative low phosphate concentration of 1.23 mg/g in the presence of the control experiment, respectively. TOC and TOM contents were 87.91, 119.04; 108.13 and 146.42 mg/g for soil sample I, and III, respectively. In all the tested parameters, the experimented soils were significantly high than the control soil sample. Molecular tests (18s rDNA.) was used to identify the pure isolate of fungus as Aspergillus tamarii. Studies on effect of incubation period on the production of peroxidase from strains of Aspergillus tamarrii sp. showed that the highest peroxidase activity was obtained on the day 6 th of the fermentation time; Peroxidase activity peaked at pH 5. Protein with highest peroxidase activity was peak precipitated at 60% saturation of the salt. The gel chroـmatogram showed single almost superimposed peaks of enzyme activity. Purified peroxidase activity peaked at pH 4.5. Optimum temperature for the enzyme activity was at 50 °C. Km and V max of 3.45mM and 280 μmole/min was extrapolated from the reciprocal curve of Lineweaver-burke at various concentrations of 2,6 DMP. Fe, Ca, Co and Mn selected as their notable impact in the active site of peroxidase guided the selected were assayed in the presence of the enzymes, respectively. The stability curve obtained for the peroxidases was single biphasic which represent the first order; the enzymes maintained greater than 50% of their activity after 30 min of incubation as activity progressively decreased upto to 40% after 60 min of incubation. Thermal stability of peroxidase at its optimum temperature (50) and at 70°C showed a biphasic stability curve. The enzymes maintained greater than 50% of their activity after 60 min of incubation.