Alkaline protease production using a membrane bioreactor

Alkaline proteases are an important class of industrial enzymes that are mainly used in detergents, and also in industries like leather, food, photography and pharmaceuticals. Most industrial processes use submerged fermentation (SMF) for alkaline protease production. Recently, solid state fermentation (SSP) has been used. This research presents the potential of an additional process for alkaline protease production, namely membrane bioreactor (MBR) system. lts application has been extended from ultrafitration operation to a potential enzyme production system. This research is therefore based on the evaluation of skinless polysulphone capillary membrane for the production of enzymes. The initial step in this project involved the experimental determination of the most suitable test organism for immobilization and biofilm formation on the membrane. This involved the use of a flow-cell chamber system with strains of Thermomyces lanuginosus ATCC 38905, T. lanuginosus ATCC 46882, Cryptococus laurentii, Aspergillus aculeatus DSM 2344, Gliocladium roseum, Penicillium grabrum, P. chrysogenum CCRC 31619, P. italicium, Saccharomyces cerevisiae, E. coli B8, Sclerotium rolfsii and a winery effluent sample comprising of a consortium of unidentified bacteria. Biofilm formation on the surface was observed visually over a period of seven days, while immobilization of the organism within the microvoids was observed microscopically using fluorescent and electron microscopy. Experimental data provided evidence that the T. lanuginosus strains ATCC 38905 and ATCC 46882, A. aculeatus DSM 2344, S. cerevisiae, E. coli and S. rolfsii were poor biofilm producers and did not demonstrate the ability to immobilize onto the membrane. G. roseum, P. glabrum, P. chrysogenum CCRC 31619, P. italicium, C. laurentii and the effluent sample were adequate biofilm producers with the ability to immobilize onto the membrane. The alkaline protease producing strain of P. chrysogenum CCRC 31619 was chosen for use for the next phase of this research.