Differences in optical trapping prompt investigations of Agrobacterium surface characteristics

Comparison of the optical trapping efficiency of Agrobacterium rhizogenes and A. tumefaciens strains indicates the A. rhizogenes strain, ATCC 11325, is significantly less efficiently trapped than A. rhizogenes A4, ATCC 15834, and the A. tumefaciens strain LBA4404. Differences were also found in capsule generation, growth media viscosity, and transmission electron microscopy negative staining. These observations imply a difference in surface structure exists. Calcofluor fluorescence suggests the difference involves an exopolysaccharide.