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An efficient method for the high-yield production of l-theanine using a newly isolated glutaminase-producing organism

Shuai, Yuying, Zhang, Tao, Jiang, Bo, Hua, Ying, Mu, Chao-Feng
Food bioscience 2019 v.28 pp. 164-169
Pseudomonas nitroreducens, enzymatic reactions, enzyme activity, glutaminase, hydrochloric acid, osmotic stress, pH, sucrose
Current enzymatic synthesis of l-theanine industrially has low yield and involves a complicated enzyme purification and post-treatment process. In this paper, Pseudomonas nitroreducens SP.001 was screened for intracellular glutaminase production. P. nitroreducens SP.001 cells were permeabilized using an osmotic shock method. The glutaminase activity of cells permeabilized with 15.5% sucrose treatment was 239% higher than that of non-permeabilized cells. The conditions for l-theanine production were optimized using the permeabilized cells. The enzyme reaction was done at 30 °C and pH 9.5 in the presence of L-Gln (0.3 M) and ethylamine·HCl (1.0 M). L-Gln was added at different rates to increase the yield of l-theanine. L-Gln (0.75 M) was converted to l-theanine (0.49 M), and the conversion rate and production rate reached 66.1% and 45.1 mmoL/h·L, respectively. Taken together, an efficient method for the high-yield production of l-theanine using permeabilized cells was developed without any detected levels of L-Gln. The method may be usable for the simple, large-scale enzymatic synthesis of l-theanine.