Sn. Wai et al., VIBRIO-CHOLERAE O1 STRAIN TSI-4 PRODUCES THE EXOPOLYSACCHARIDE MATERIALS THAT DETERMINE COLONY MORPHOLOGY, STRESS RESISTANCE, AND BIOFILM FORMATION, Applied and environmental microbiology (Print), 64(10), 1998, pp. 3648-3655
Vibrio cholerae O1 strain TSI-4 (El Tor, Ogawa) can shift to a rugose
colony morphology from its normal translucent colony morphology in res
ponse to nutrient starvation. We have investigated differences between
the rugose and translucent forms of V. cholerae O1 strain TSI-4. Elec
tron microscopic examination of the rugose form of TSI-4 (TSI-WR) reve
aled thick, electron-dense exopolysaccharide materials surrounding pol
ycationic ferritin-stained cells, while the ferritin-stained material
was absent around the translucent form of TSI-4 (TSI-4/T). The exopoly
saccharide produced by V. cholerae TSI-4/R was found to have a composi
tion of N-acetyl-D-glucosamine, D-mannose, 6-deoxy-D-galactose, and D-
galactose (7.4:10.2:2.4:3.0). The expression of an amorphous exopolysa
ccharide promotes biofilm development under static culture conditions.
Biofilm formation by the rugose strain was determined by scanning ele
ctron microscopy, and most of the surface of the film was colonized by
actively dividing rod cells. The corresponding rugose and translucent
strains,were compared for stress resistance. By having exopolysacchar
ide materials, the rugose strains acquired resistance to osmotic and o
xidative stress. Our data indicated that an exopolysaccharide material
on the surface of the rugose strain promoted biofilm formation and re
sistance to the effects of two stressing agents.