Complementation by restricted phage T1.

The ability of restricted phage T1hr to complement stocks of T1am mutants carrying the P1 modification has been tested in mixed infection of Escherichia coli B(P1). Of the 18 genes tested, 15 could be complemented to give successful infection of approximately 10 to 25% of the cells, and 2 other genes consistently gave at least 5% complementation. The progeny phage produced in these infections was predominantly of the hr(+)am genotype. A mutant in gene 12 could be complemented very poorly, if at all. With one double mutant stock, the complementation obtained was nearly as good as the more poorly complemented of the two corresponding single mutants.