Acid pH responses of Escherichia coli: inhibition of colicin V synthesis and activity at pH 5.0.
On solid medium, streaks of ColV+ Escherichia coli strains produced much larger inhibitory zones on sensitive indicators at pH 7.0 and 9.0 than at pH 5.0. Such an acid pH effect also occurred in liquid medium, with sensitive strains being killed by ColV+ ones at pH 7.0 or 9.0 but not at pH 5.0. Colicin V was responsible for the killing effect. Culture filtrates from PAP1401 (ColV+) were used to examine the basis for the pH effect and it was found that acid pH interfered directly or indirectly with colicin V production but that colicin V was not irreversibly inactivated at pH 5.0. Additionally, colicin V formed at pH 7.0 was less active when tested on sensitive strains at pH 5.0 than at pH 7.0. Neither reduced colicin synthesis nor its reduced activity can be attributed to increased availability of iron at pH 5.0.
Rowbury
R J
RJ
Department of Biology, University College London, Great Britain.
Goodson
M
M
D003087:Colicins / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000378:metabolism; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D013045:Species Specificity
D003087:Colicins