Optimization Of Fermentation Medium Of Microbial Transglutaminase

Microbial transglutaminase (protein-glutamine- γ-glutamytransferase, MTG) is an enzyme, which can catalyze acyl transfer reactions in vitro introducing covalent cross-links between proteins as well as peptides and various primary amines. These transglutaminase catalyse reaction can be used to modify the function of proteins. Therefore, MTG was interested because its potential application in food, cosmetic, pharmacy and other industries. However, the low productivity of strain of MTG is a key factor that prevents the application of MTG on an industrial scale. To improve the productivity of MTG is a main task in this thesis. Several methods were studied in this thesis to improve the productivity of MTG, including screening high productivity strains, optimizing fermentation medium and optimizing the culture condition and so on.In order to increase MTG activity, the main method is flask-shaking batch fermentation. The main contents of the research are as follows: First, Streptomyces sp. HS-1 was used as original strain to screen the high productivity strains, and the right methods of Streptomyces sp. conservation were selected. Second, several important singal fermentation medium factors were investigated. Third, the effects of different soybean hydrosylate on MTG activity were studied. Fourth, the optimal fermentation medium with SAS was investigated. Fifth, fermentation of Streptomyces sp.HS-2 in 10L fermentor.Main results are as follow:(1) One high productivity strain was selected by studying the MTG activity from 300 strains randomly, named as HS-2. Three methods for Streptomyces sp. conservation were studied and freeze-drying was the best way in the three methods.(2) When Zn²⁺ was added in the fermatation medium, the activity of MTG was increased slightly. However, bean oil and rape oil, and several surfactants decreased the activity of MTG Results showed that the MTG activity was increased by adding corn plasm into fermentation medium from 7.42u/mL to 8.66u/mL, and the optimal concentration of corm plasm was 12ug/mL.(3) Effects of different hydrolysate of soybean on MTG production and MTG activity were studied. Results showed that soybean from Norway had the best effect...