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This studies were designed to improve the productivity of L-lysine by protoplast fusion and immobilized system of fusants using strains of Brevibacterium flavum ATCC 21528, Brevibacterium lactofermentum ATCC 21086 and Corynebacterium glutamicum 820. Mutants were isolated with concentration method of 300g/ml penicillin-G after treatment of 250μg/ml N-methyl-N-nitro-N-nitrosoguanidine. B. flavum 37-2(Hos_-, Kan_r, AEC_r), B. lactofermentum 6-2(Ile´, Val-, Str_r, AEC_r) and C. glutamicum 57-5(Met_-, Thr_- , Rif_r, AEC´) were isolated from mutants. Protoplasts were induced by being incubated with 500μg/ml lysozyme of lysis solution for 6 hr and the ratio of protoplast formation and regeneration were ranging from 97-99 and 33-37, respectively. Fusion frequencies of fusants of BBFL 21, BCFG 37 and BCLG 59 were shown in the range from 1.25 x 10_(-6) to 5.83 x 10_(-7) under the optimum conditions. The fusant BBFL 21 showed the highest productivity of 411.1 ng/ml·hr L-lysine in the lysine productivity broth at 30 C for 72 hr. In the immobilization systems, fusant BBFL 21 was employed in various polymer matrices such as sodium alginate, polyacrylamide, agar and a-carrageenan. The immobilization of sodium alginate showed the highest productivity of 413 ng/ml hr L-lysine in the batch system. Continuous fermentation of immobilization system by using tube fermentor was produced the highest productivity 416.7 ng/ml·hr L-lysine under optimum condition.
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