Fed-batch Fermentation And Dynamic Model Of Microbial Transglutaminase

The transglutaminase can catalyze acyl transfer reactions in vitro introducing covalent cross-links between proteins as well as peptides and various primary amines. This reaction can change the properties of protein, increasing function characteristics and nutrition of protein. So the transglutaminase plays more and more important role in the food technology. Commercial transglutaminase has been mainly from animal tissues in the beginning stage. The scarce source and complicated isolation and purification procedures result in an extremely high price of the enzyme. Therefore it is not possible to apply such expensive tissue-type transglutaminase into food processing on an industrial scale. Microbial transglutaminase (MTG) has been produced from microorganisms. MTG is only studied for a few years, and there are some problems in the large scale production MTG, so lots of work must be done for the MTG use in a commercial way.The main studies were taken as follows:The Streptoverticillium mobaraense fermentation medium was optimized by flask batch culture. The fed-batch fermentation method was studied by flask culture based on the optimal medium. Then the fed-batch fermentation method was studied in 10L fermenter, which founded the base for industrial production. The MTG batch fermentation model was developed base on the data of 10L batch fermentation.The main results were as follows:1. The industrial optimal meidum: Starch:0.5%, Glucose: 2.0%, Yeast stract: 0.5%, soy hydrolysis : 2.0%, (NH₄)₂SO₄ 0.3%, MgSO₂·7H₂O : 0.2%, K₂HPO₄·3H₂O: 0.2%,Mg₃(PO₄)₂:1.0%,pH7.42. In flask fed-batch fermentation, the best carbon source was glucose, and the best feed time and feed concentration was 24h and 1.0%, respectively. That glucose divided into twice and feed at 12h and 24h can get the highest MTG production, which MTG activity (5.56 u·ml^-1) was 20.87% higher than the control (4.6u·ml^-1) and also was higher than 1.0% glucose once feed at 24h (5.12 u·ml^-1). It was no obvious effect to feed nitrogen source, with organic nitrogen source or inorganic nitrogen source.3. The fed-batch fermentation was feed from 8h with pH controlled. The results showed that relative slow feeding rate (0.01 L·h^-1and 0.02 L·h^-1) promoted the cell...