Variation of Lipopolysaccharide among the Three Major Agrobacterium Species and the Effect of Environmental Stress on the Lipopolysaccharide Profile

Lipopplysaccharide (LPS) is a variable component among the bacterial species as wall as strains of a single species and this characteristic is helpful for discrimination between strains. However, we have only limited information about LPS variation and influence by environment in Agrobacterium strains. In this study, we analyzed variation of lipopolysaccharide (LPS) among 34 Agrobacterium strains; 9 strains of A. tumefaciens, 15 strains of A. rhizogenes, 9 strains of A. vitis and one A. rubi strain. Most of the A. tumefaciens strains and every A. rhizogenes strains had high and low molecular weight LPS molecules (LPS I and LPS II, respectively). On the contrary, every A. vitis strains and two exceptional A. tumefaciens strains lacked LPS I but had a single LPS II band. The LPS profiles were stable phenotype in the Agrobacterium strains. Abiotic stresses such as high salinity, high and low pH and high and low temperature were given to representative strains in each species. Only a little alternation in the LPS profiles was observed under the stress conditions except the high temperature to LPS I. Cultivation at 35°C or higher resulted in a significant size reduction of LPS I in A. tumefaciens C58 strain down to the size similar to that of LPS II which attenuated the tumor formation. On the contrary, cultivation at the high temperature induced the exceptional A. tumefaciens strain MAFF 03-01001 to synthesize LPS I, which was absent at lower temperature in the strain. This phenomenon has never been observed so far at least in the family Rhizobiaceae.