 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|||||||||||||||
 |
 |
 |
 |
 |
 |
 |
|
|||||||||
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
|||||||
 |
 |
|
||||||||||||||
 |
 |
 |
|
|||||||||||||
 |
|
|||||||||||||||
 |
|
|||||||||||||||
 |
|
|||||||||||||||
Strain Information
E. coli K-12 MG1655
Description
Genotype: F- lambda- ilvG- rfb-50 rph-1
Serotype: OR:H48:K-
This strain was sequenced by the Blattner laboratory because it approximates wild-type E. coli and "has been maintained as a laboratory strain with minimal genetic manipulation, having only been cured of the temperate bacteriophage lambda and F plasmid by means of ultraviolet light and acridine orange, respectively." [1]. The mutations listed in the genotype are present in most K-12 strains and were probably acquired early in the history of the laboratory strain. A frameshift at the end of rph results in decreased pyrE expression and a mild pyrimidine starvation, such that the strain grows 10 to 15% more slowly in pyrimidine-free medium than in medium containing uracil [2]. The ilvG- mutation is a frameshift that knocks out acetohydroxy acid synthase II [3]. The rfb-50 mutation is an IS5 insertion that results in the absence of O-antigen synthesis [4].
MG1655 was derived and named by Mark Guyer from strain W1485, which was derived in Joshua Lederberg's lab from a stab-culture descendant of the original K-12 isolate. This original E. coli strain K-12 was obtained from a stool sample of a diphtheria patient in Palo Alto, CA in 1922 [5].
References:- Blattner, et al (1997) The complete genome sequence of Escherichia coli K-12. Science 277(5331), 1453-1462. PMID: 9278503
- Jensen (1993) The Escherichia coli K-12 "wild types" W3110 and MG1655 have an rph frameshift mutation that leads to pyrimidine starvation due to low pyrE expression levels. J Bacteriol 175(11), 3401-3407. PMID: 8501045
- Lawther, et al. (1982) DNA sequence fine-structure analysis of ilvG (IlvG+) mutations of Escherichia coli K-12. J Bacteriol 149(1), 294-298. PMID: 7033211
- Liu and Reeves (1994) Escherichia coli K12 regains its O antigen. Microbiology 140(Pt 1), 49-57. PMID: 7512872
- Bachmann (1996) Derivations and Genotypes of Some Mutant Derivatives of Escherichia coli K-12. p2460-2488 in Neidhardt (ed), Escherichia coli and Salmonella, 2nd Edition ASM Press, Washington DC
Media and growth curves
MG1655 grows on LB and M9 minimal medium (+ Glucose + 1ug/ml thiamine). In doing experiments with microarrays, we sought a medium that was both defined and reproducible (unlike LB), yet supported fast growth rates. We now use Neidhardt's MOPS-based rich defined medium (MOPS-RDM). We also sought a commercially available rich defined medium, and finding none tried to grow MG1655 on a medium sold for mammalian cell culture. It grows quite well, but we decided to stick with Neidhardt's medium because it shows a sharper transition to stationary phase.
Recipe for MOPS Rich Defined Medium and MOPS Minimal Medium
Growth curve for MG1655 on MOPS Minimal Medium
Growth curves for MG1655 on M9 Minimal Medium