Production of theanine by Xerocomus badius (mushroom) using submerged fermentation

Theanine is a rare amino acid mainly produced by the genus Camellia, which is also found in the Basidiomycete fungus (mushroom) Xerocomus badius. Besides its favorable taste, broad potential physiological effects have been reported in the recent years, leading to the very fast growing demand for theanine worldwide. Thus a series of methods to produce theanine have been developed, including tea callus cultivation, chemical synthesis, extraction from the fresh leaves of the tea plant, and enzymatic synthesis. Different from the previous procedures, we reported here a novel protocol to produce theanine from the mushroom X. badius by means of submerged fermentation. Moreover, response surface methodology (RSM) was employed to optimize various parameters during fermentation. The statistic results indicated that the maximum theanine yield of X. badius (17.2420 mg/L) could be achieved at the optimal conditions, with glucose of 29.17 g/L, yeast extract of 6.38 g/L in a broth volume of 61.43 mL (within a flask of 250 mL) at an initial pH at 5.63. These predicted values were also validated by experiments. Taken together, these findings provided us a promising strategy for the production of theanine from X. badius in addition to the traditional preparation processes.