Improved inulinase activity by Penicillium purpurogenum grown in microwave pretreated coffee spent by L16 orthogonal design of experiment

Abstract

Inulin belongs to non-digestible carbohydrate, storage polysaccharide, widely distributed in grasses and other plants. Recently, inulin has gained significant economic importance and received great interest because they can represent as cost effective and abundant substrate for the production of microbial inulinases with commercial viability. In this aspect, we have investigated the microwave assisted pretreatment process of coffee spent for effective inulin extraction and thereby, better inulinase activity. In the present study, fungal species showing high inulinase activity have been isolated from rhizosphere region of soil samples collected from Non such estate, Coonoor and Yercaud, India. Two different species viz., Penicillium purpurogenum (0.953 U/ml) and Aspergillus tamarii (0.432 U/ml) showed maximum inulinase activity. Under normal inulin extraction conditions the inulinase activity by Penicillium purpurogenum has been observed as 28.08 U/ml (29.46 fold increase) whereas, maximum inulinase activity was recorded as 42.57 U/ml (44.67 fold increase) by the pretreatment (inulin extraction) of coffee spent using microwave assisted extraction (MAE). The optimum conditions of MAE of inulin with improved inulinase activity were found to be 540 watts, 1: 25 material ratio and 30 seconds. Based on the results MAE may be considered as significant and cost effective method for inulin extraction.