Identification and characterization of a novel Old Yellow Enzyme from Bacillus subtilis str.168

We identified and characterized YqiG, a novel Old Yellow Enzyme (OYE) from Bacillus subtilis str.168 , as a member of the “thermophilic-like” subfamily. It is most related to XenA from Pseudomonas putida , with 37.9% identity, but it exhibits certain differences in sequence and enzyme properties. The YqiG can reduce various activated alkenes and exhibits high temperature (60   °C for 12   h) and pH stability (pH 4.0 and 9.0 for 12   h), which indicates that it has a great potential for biocatalysis. However, it shows low tolerance toward organic solvents. Also the YqiG shows high activities towards maleimide, dimethyl maleate and acyclic ketones (55.5   U/mg, 6.22   U/mg and 2.97   U/mg, respectively). Besides, The YqiG can catalyze citral to (S)-citronellal with a low rate but high ee% (>99%).