Isolation of Thermotolerant Inulinase-producing Bacteria from Compost using Enrichment and Baiting Techniques

Abstract

Despite the growing demand for thermostable inulinases, only a limited number of microorganisms have been identified as producers of inulinase. While fungi and yeasts are known to produce large amounts of inulinase, bacterial inulinases exhibit greater thermostability, making them ideal for diverse industrial applications. This investigation aims to isolate thermotolerant bacteria from compost using two isolation methods - enrichment and baiting. The two techniques are compared in terms of the population of bacteria isolated and the mean enzyme activity across different temperatures. Both methods yielded a comparable number of isolates, but their performance differed in terms of enzyme activity and optimum temperature. The enrichment technique exhibited an optimal temperature of 46.3°C with an enzyme activity of 2.96 U/mL, whereas the baiting method showed 44.4°C and 1.56 U/mL, respectively. These findings suggest that enrichment is a more effective strategy than baiting for isolating thermotolerant bacterial producers of inulinase. The investigation resulted in the isolation of Bacillus sonorensis and a novel thermophilic strain, Aneurinibacillus thermoaerophilus, both capable of producing the inulinase enzyme.