排序方式: 共有42条查询结果,搜索用时 31 毫秒
41.
42.
Widespread distribution of deletions of the bgl operon in natural isolates of Escherichia coli 总被引:2,自引:0,他引:2
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.
相似文献