Abstract
We compared the sensitivity of new Escherichia coli tester strains having the TolC outer membrane transport protein mutation (tolC strain), viz., WP2tolC, WP2tolC/pKM101, WP2uvrA,tolC and WP2uvrA,tolC/pKM101, with E. coli strains not carrying this mutation (non-tolC strain), i.e., WP2, WP2/pKM101, WP2uvrA and WP2uvrA/pKM101, by measuring the specific activity (revertants/mg) of mutagens using a preincubation method. The tolC strains were more sensitive to polycyclic and heterocyclic compounds such as 2-aminoanthracene, 2-nitrofluorene, Glu-P-1, benzo[a]pyrene, mitomycin C, streptonigrin and doxorubicin than the non-tolC strains. Mutagenicity of 2-nitrofluorene was not detected by non-tolC strains WP2, WP2/pKM101 and WP2uvrA, but was detected by their tolC counterpart strains WP2tolC, WP2tolC/pKM101 and WP2uvrA,tolC. However, these tolC strains were less mutagenic to streptozotocin or cisplatin than that of parent strains. Mutagenicity of 9-β-D-arabinofuranoside was also not detected by the tolC strain WP2uvrA,tolC/pKM101, but was detected by the non-tolC strain WP2uvrA/pKM101. The enhancing effects of the mutagen detecting sensitivity by TolC outer membrane transport protein mutation were clearly observed with the low sensitivity strain WP2, but less clearly with the high sensitivity strain WP2uvrA/ pKM101.
