Production, purification and characterization of Inulinase from fungus of dahlia rhizosphere

Abstract

Inulinase and its studies are of immense importance in the present scenario. The use of microbial inulinases is suggested as a very potential approach, however, for obtaining inulinase in sufficient quantity from microbes, particularly fungii, optimization of the growth parameters is essential. The current study is focused over extraction of inulinase from fungal strains isolated from rhizospheric soil of dahlia plant and optimization of growth parameters. In a total of ten isolates, two organisms Fusarium oxysporum and Aspergillus sp. were identified as efficient inulinase producers. The optimum incubation time, temperature and pH of these organisms were found to be 40 min, 65°C at 6.5 pH and 30 min, 50°C at 6.5 pH respectively. Inulin was identified as appropriate carbon source for these microbes. Thin layer chromatography validated the presence of hydrolysis product via the action of inulinase on inulin into fructose unit. The highest enzyme activity and Specific activity was obtained from Aspergillus spp. for 20% fractionate was 1.81U/ml and 2.288U/mg, for 40% fractionate was 0.735U/ml and 1.047U/mg and for 60% fractionate was 3.74U/ml and 12.47U/mg respectively at the optimized condition. DEAE Sephadex A 50 Ion exchange column chromatography show that the fifth fraction of 20% fractionate had shown the maximum enzyme activity. The molecular weight of this enzyme was estimated at 66±2kDa and 43±2kDa using SDS-PAGE after ammonium sulphate precipitation, dialysis and chromatography analysis which showed exo-inulinase type.