Immobilized Deekunha Aeruginosa Production Of L-alanine

A process to obtain optically pure L-alanine had been developed using a L-aspartate beta-decarboxylase(ADL)-producing bacterium Pseudomonas dacunhae. Efforts were made to obtain the optimal culture medium and the optimal culture conditions. The results were given as follows: fumaric acid 0.5%, peptone 3%, KH2PO4 0.05%, MgSO4 0.01%, pH7.2, at 30 of culture temperature and 24~26-hour of culture time.Based on the above results, a method for producing L-alanine from L-aspartic acid using immobilized Pseudomonas dacunhae cells was investigated in this thesis. The cells were immobilized with K-carrageenan and treated with two kind of hardening agents. 88.6% of yield of ADL activity was obtained and only 3.5% of ADL activity decreased within 60 days at 4. The optimal temperature, the optimal pH value and the optimal substrate(L-aspartic acid) concentration for the enzymatic reaction by ADL were 40, 5.0 and 66.5~133g/L, respectively. Also, the activation of the substrate solution on ADL activity was studied. ADL activity significantly increased by culturing the immobilized cells in 150g/L substrate solution in the rotatory shaker at37 for 30 hours.A packed bed reactor filled with the immobilized cells was developed to continuously produce L-alanine from L-aspartic acid. The reactor with100g/L substrate solution had been running for 20 days at 37. The half-life was then determined as 71 days and the crystal powder sample, containing more than 98.61% of L-alanine, was obtained.