Large deletions in the region of the replication termination of Escherichia coli K-12 chromosome

The Escherichia coli strain PLK1427 (Henson, Kopp, Kuempel, 1984) was used in this work. It carries a deletion of 60 thousand pairs of nucleotides in the chromosomal region 30-31 min and a partially deleted prophage lambda rev cI875Sam7 integrated into the 30 min region, instead of the rac prophage. Among the mutants of PLK1427 strain selected for resistance to 42 degrees C, deletions extending about 4 min and affecting the loci nirR (29.3 min), zdc235::Tn10 (32.3 min) and zdd230::Tn9 (33.3 min) were found. Although the deletion mutants obtained affect the region of replication termination (terC) of the chromosome, they have no alterations in the growth rate. It was demonstrated that some deletions may be transferred and are capable of recombination, giving the wild type in transductional experiments with the mutant phage T4.