The lactose system inKlebsiella aerogenesV9A: 1. Characteristics of two Lac mutant phenotypes which revert to wild-type
- 1 October 1972
- journal article
- research article
- Published by Hindawi Limited in Genetics Research
- Vol. 20 (2), 175-191
- https://doi.org/10.1017/s0016672300013690
Abstract
A wild strain of Klebsiella aerogenes (V9A), which contains a plasmid Fklac carrying the genes of the lac operon, gives two mutant cell types, recognized by the appearance of their colonies on MacConkey lactose agar. These are referred to as ML− and ML−/+, wild-type being ML+. ML− cells can grow rapidly on 1% lactose as carbon source but very slowly on 0·2% unless induced by TMG or D-fucose, or by previous growth on galactose, melibiose or raffinose, which enables them to grow rapidly on 0·2% lactose for 2–4 cell generations. Previous growth on 1% lactose does not induce the ability to grow rapidly on 0·2% lactose. It is concluded that ML− cells have a defect in the lactose permease gene which allows slow uptake of lactose when the external concentration is 0·2% and more rapid uptake when the external concentration is increased. In addition, TMG, D-fucose, galactose, melibiose and raffinose induce one or more other galactoside permeases which can accumulate lactose efficiently but are not induced by lactose. ML−/+ cells can grow normally on 0·2% lactose as carbon source, but only after a substantial lag when transferred from glucose, glycerol or sucrose, and after an even longer lag when transferred from melibiose or raffinose. Wild-type cells (ML+) grow normally on 0·2% lactose after a short lag of less than a cell generation time, when transferred from any other carbon source. Cells of each of the three phenotypes (+, −/+ and −) can mutate to give both of the other two phenotypes. Incomplete genetic evidence suggests that the ML− mutation is a result of a reversible change in the Fklac plasmid.Keywords
This publication has 9 references indexed in Scilit:
- FK-lac, an Episome with Unusual Properties found in a Wild Strain of a Klebsiella SpeciesNature, 1970
- The Genetics of Penicillinase Production in Staphylococcus aureus Strain PS 80Journal of General Microbiology, 1969
- Transport systems for galactose and galactosides in Escherichia coliJournal of Molecular Biology, 1968
- GENETIC CONTROL OF THE MEMBRANE PROTEIN COMPONENT OF THE LACTOSE TRANSPORT SYSTEM OF Escherichia coliProceedings of the National Academy of Sciences, 1967
- THE VOGES‐PROSKAUER REACTION AND ITS SIGNIFICANCE: A REVIEWJournal of Applied Bacteriology, 1961
- BacteriophagesPublished by Biodiversity Heritage Library ,1959
- The Life of BacteriaSoil Science, 1955
- Measurements of rate of mutation of flagellar antigenic phase inSalmonella typhi-muriumEpidemiology and Infection, 1949
- A SIMPLE METHOD for DEMONSTRATING the PRODUCTION of GAS by BACTERIABMJ, 1898