www . Science-Projects . com

THE PEDIGREE OF E.coli W3110
E.coli K-12 wildtype (F+ λ+)
X-ray	U.V. Light
58 F+ λ+ bio-1 spoT1	W1485 F+ λ-	W1485E Yanofsky λ- supE42
X-ray	spontaneous mutant from motility agar
58-161 F+ λ+ bio+ spoT1 metB1	W2637 F- λ- gal- (weak)
spon- taneous	spontaneous mutant from EMB(gal)
W6 F+ λ+ spoT1 metB1 relA1	W3110 F- λ- IN (rrnD-rrnE)1
most of old Hfr's

References: see Bachmann 1972 Bacteriol. Rev except: note that (1) spoT1 is now known to have arisen in 58 (M. Cashel - personal commun.); (2) Lederberg's W1485 does not carry supE42 but the strain called "W1485" by Yanokshy does; and (3) the inversion of approx 20% of the chromosome in W3110 was discovered by Hill and Harnish 1981 PNAS 78:7069.

A Seemingly Common Myth about the Origin of E. coli K-12

Many of us have heard that K-12 was the row and seat number of a student of Joshua Lederberg in his early days. This student, along with her classmates, produced auxotrophic strains of separately isolated Bacillus coli (as it was known then) such that one strain was met^- and the other was leu^-. This particular student was the only one in the class to find upon mixing them that a prototrophic recombinant strain was produced. Thus the powerful genetic tool of "sexual" E. coli was discovered.

HOWEVER: according to Joshua Lederberg, no such row and seat number is part of the story, and that K-12 was merely one of the many accession numbers in the Stanford University culture collection. What is more is that strain K-12 was isolated in 1922, which was before Lederberg was born (1925).

The Real Story is being researched and assembled.

|Site's Table of Contents | Site's Index |