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Characterization of a Nalidixic‐Acid‐Resistant Mutant of Escherichia coli as a Strict Aerobe
Author(s) -
Yoshizawa Yukio,
Yamamoto Nobuto
Publication year - 1989
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.1989.tb01994.x
Subject(s) - biology , nalidixic acid , escherichia coli , pbr322 , mutant , ethidium bromide , agarose gel electrophoresis , mutation , dna , gene , acriflavine , gel electrophoresis , microbiology and biotechnology , genetics
An Escherichia coli mutant, C18, which plates at an efficiency of 5.0 × 10 −4 under anaerobic condition, was isolated among spontaneous nalidixic‐acid‐resistant mutants. This strict aerobic mutation was mapped by Pl cotransduction with a gyrA linked transposon Tn10 and found to be at the gyrA gene. A low degree of superhelicity of pBR322 DNA isolated from C18 was demonstrated by agarose gel electrophoresis with various concentrations of ethidium bromide. The superhelical density of pBR322 isolated from C18 was 80% of the value of pBR322 isolated from wild‐type bacteria cultured under aerobic condition, and 50% cultured under anaerobic condition. These results lead us to conclude that a certain mutation of the gyrA gene causes a decrease in DNA superhelicity and prevents anaerobic growth.