A new biochemical method for more efficient production of Nalpha-benzyloxycarbonyl-L-aminoadipate delta-semialdehyde (Nalpha-Z-L-AASA) and Nalpha-Z-D-AASA was developed with cells of Rhodococcus sp. AIU Z-35-1. Using the cells harvested after 1 d of cultivation, more than 95 mM Nalpha-Z-L-AASA was produced from 100 mM Nalpha-Z-L-lysine by incubating at pH 5.0 for 1 d at 30 degrees C or by incubating at pH 7.0 for 2 d at 10 degrees C. A similar conversion yield of Nalpha-Z-D-AASA was also obtained under the same conditions. These reaction times required were 1/4 and 1/2 of the respective ones by the method with amine oxidase, and the yields of Nalpha-Z-L-AASA and Nalpha-Z-D-AASA were 2 times higher than the respective ones by the method with amine oxidase. In addition, this method had the advantages of not requiring purification of enzyme and addition of catalase. Thus, the microbial method proposed here was superior to the chemical and other biochemical methods in simplicity, reaction rate, and yield.