title: Widespread distribution of deletions of the bgl operon in natural isolates of Escherichia coli.
abstract: A deletion that includes the bgl (beta-glucoside utilization) operon of Escherichia coli was originally detected in several rarely occurring natural isolates that utilize cellobiose. Here I show that bgl deletions are present in 95% of the Cel+ isolates obtained from diverse sources. They are also present in 29% of the Cel- strains in two different collections of natural isolates of E. coli. At least three versions of bgl deletions are present in E. coli populations. In the most common version approximately 8 kb of DNA around the bgl region of E. coli K12 is replaced by a specific 6.5-kb DNA fragment. In another version a deletion of similar length is not replaced by the same sequence. A third version involves deletion of approximately 14 kb without the replacement fragment being present. The distribution of these deletions suggests that the version 1 deletion occurred very early in the history of E coli. It also appears likely that there is selection for bgl deletions in Cel+ strains of E. coli. The presence of the version 1 deletion within distantly related phylogenetic groups of E. coli provides evidence for recombination within natural populations of E coli.
mesh_terms: D002475:Cellobiose / Q000378:metabolism*; D002872:Chromosome Deletion; D002874:Chromosome Mapping; D004187:Disaccharides / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics*; D005960:Glucosides / Q000378:metabolism*; D006027:Glycosides / Q000378:metabolism*; D009876:Operon
chemical_list: D004187:Disaccharides; D005960:Glucosides; D006027:Glycosides; D002475:Cellobiose