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Abstract
Transformation of Escherichia coli with foreign DNA is dependent on DNA binding and translocation at the cell surface. E. coli D23 is a mutant strain that contains two additional mutations, mreB11 (e nvB ) and sloB1, in comparison to the parent strain E. coli D21. These two mutations alter the cell morphology into a sphere with decreased surface area and cause growth rate to slow down in comparison to E. coli D21 which maintains the growth rate and rod shape that are associated with wild type E. coli. This study investigated the effect of decreased cell surface area, produced by the mreB11 and sloB1 mutations in the E. coli D23, on the transformation efficiency. Both E. coli strains D21 and D23 were transformed with a plasmid encoding a kanamycin resistance by using a calcium chloride/heat shock -5 method. E. coli D23 cells had a transformation frequency of 1.1 x 10 transformants/cell -6 surviving transformation while E. coli D21 cells had a transformation frequency of 1.2 x 10 transformants/cell surviving transformation. Our results demonstrate that E. coli D23 cells show increased transformation efficiency compared to E. coli D21, with 755 and 83 transformants/µg DNA respectively, suggesting that one of these mutations or possibly both may contribute to this increase by means of removing the physical barrier to foreign DNA and/or upregulating competence genes to facilitate DNA entry. However, the relative contribution of each of these mutations on the enhanced transformation still needs to be determined.