大腸菌K-12株,L-型の分離とその性質

Suspension of Escherichia coli K-12 was sequentially treated with N-methyl-N-nitro-N-nitrosoguanidine and lysozyme,and its L-forms were selected on brain heart infusion (BHI) agar medium. Of those clones,L-form NC7 was adapted to grow in a liquid cultue with osmotic stabilizer. The L-form NC7 was stable in penicillin-free medium. Morphology of this L-form NC7 agreed with that described for other bacterial L-forms in many respects. The L-form NC7 multiplied in soft agar (0.5%, W/V), but did not in hard agar (1.5%, W/V). In osmotic stabilizers tested,NaCl was most effective in the range of 2 to 3% (W/V). In BHI medium containing NaCl CaCl_2 was required for growth of the L-form NC7. Studies of the growth characteristics for L-form NC7 gave the following results:an optimal temperature of 32℃, an optimal pH of 7 to 8,and no requirement for serum . This L-form NC7 also retained many of the physiological characters of the parent strain.