Researches On Trehalose Synthesis From Dextrin By A Trehalose Synthase From Brevibacterium Helvolum

Trehalose was first described in the early 19th century as a component of the ergot of rye, later it was discovered in a great variety of species, most notably the anhydrobionts.In this article, a method of using Brevibacterium helvolum converting liquefied starch to product trehalose was described. Several conditions, which influence the growth of strains screened from culture dish and test tube slant, such as medium component, temperature, initial pH and growth time, were evaluated. Conditions such as temperature, pH, substrate structure, substrate concentration and activator which affect enzymatic reaction were also studied, respectively.Under the condition of 27°C and pH6.5, 80mL medium was put into a 500mL flask with a 6% inoculum concentration. After 3 days oscillating culture the density of cell reached maximum and dextrin proved to be a better carbon source for Brevibacterium helvolum to produce trehalose synthase. A 5% liquefied starch with a DE of 20 was converted by this cell under 35℃ and pH6. 5 and the conversion ratio was above 70%.Maltose was found to have obvious influence on the detection of trehalose concentration in the reaction mixture containing glucose, maltose and trehalose mainly. By changing the ratio of acetonitrile and water, maltose and trehalose were finally completely separated when the ratio was 80:20. So the HPLC analysis of trehalose in fermentation broth can be done by using a Carbohydrate Analysis column with an injection of 20L sample and then eluting with a solvent containing acetonitrile and water (80:20) at a flow rate of lmL/min at room temperature. The retention time of maltose and trehalose was about 11.3 and 13.8 minutes respectively.