This study was designed to investigate the stability of a lipase fused with a cellulose-binding domain (CBD) to cellulase. The fusion protein was derived from a gene cluster of a CBD fragment of a cellulase gene in Trichoderma hazianum and a lipase gene in Bacillus stearothermophilus L1. Due to the CBD, this lipase can be immobilized to a cellulose material. Factors affecting the lipase stability were divided into the reaction-independent factors (RIF), and the reaction-dependent factors (RDF). RIF includes the reaction conditions such as pH and temperature, whereas substrate limitation and product inhibition are examples of RDF. As pH 10 and 50°C were found to be optimum reaction conditions for oil hydrolysis by this lipase, the stability of the free and the immobilized lipase was studied under these conditions. Avicel (microcrystalline cellulose) was used as a support for lipase immobilization. The effects of both RIF and RDF on the enzyme activity were less for the immobilized lipase than for the free lipase. Due to the irreversible binding of CBD to Avicel and the high stability of the immobilized lipase, the enzyme activity after five times of use was over 70% of the initial activity.
All Science Journal Classification (ASJC) codes
- Applied Microbiology and Biotechnology
- Biomedical Engineering