A CLOSE CORRELATION BETWEEN IMPROVEMENT OF ORGANIC-SOLVENT TOLERANCE LEVELS AND ALTERATION OF RESISTANCE TOWARD LOW-LEVELS OF MULTIPLE ANTIBIOTICS IN ESCHERICHIA-COLI

We have isolated cyclohexane-tolerant mutants from Escherichia coli st rain JA300, which is cyclohexane-sensitive and n-hexane-tolerant. Thes e mutants were resistant to low levels of ampicillin, chloramphenicol, nalidixic acid, and tetracycline, and were sensitive to a low level o f kanamycin. Spontaneous clones resistant to low levels of the antibio tics, isolated from JA300, showed altered levels of organic solvent to lerance. The clones resistant to ampicillin and chloramphenicol had cy clohexane tolerance. Some of the resistant clones had cyclohexane and n-pentane tolerances. On the other hand, some kanamycin resistant clon es became sensitive to n-hexane. Therefore, mechanisms to improve tole rance levels toward organic solvents are closely correlated with some antibiotic resistant system to low levels of antibiotics.