Patent ID: 8211674

Claim:
A method of making theanine comprising the steps of: deriving a glutaminase from a culture of one or more microbes selected form the group consisting of Bacillus amyloliquefaciens, Bacillus coagulans, Aspergilus niger, Rhizopus stolonifer, Saccharomyces cerevisiae, Saccharomyces rouxii, Candida utilis , and Candida Antarctica ; and reacting glutamine and an ethylamine with the derived glutaminase under conditions suitable to synthesize the theanine, wherein (i) the microbes are cultured so that the culture supernatant of the microbes has a specific activity of not less than 10 mU/mg, (ii) a ratio of the theanine synthesized from the glutaminase as a main product to glutamic acid synthesized from the glutaminase as a by-product is larger than 5, (iii) the method has a pH in a range of 9 to 12, (iv) the mol conversion ratio of L-glutamine to theanine is at least 70%, and (v) the mol conversion ratio of L-glutamine to glutamic acid is not more than 6%.