Transformation in E. coli K12: relation of linkage to distance between markers.

E. coli K12 transformants, selected as leu+ or pyrA+ transformants, were analysed for inheritance of some closely linked unselected markers. Based on the observation that the number of recombinants which require, besides an integration event, one or more crossing-over events was negligible, a simple mapping function was deduced. The function L= e-kd, which directly relates observed linkage of an unselected marker and the relative distance of that unselected marker to the selected marker, gave a consistent interpretation of the experimental results.