Visualization of an extracellular mucoid layer of Treponema denticola ATCC 35405 and surface sugar lectin analysis of some Treponema species

Slime layers and capsules are common amongst medically relevant bacteria. We herein report that Treponema denticola, which has been associated with periodontitis, synthesizes or acquires an extracellular polysaccharide layer that we have observed through electron microscopy using the polysaccharide-specific dye Alcian blue and phosphotungstate. We have also visualized this extracellular layer by dark-field microscopy of Alcian blue-stained spirochete cells. A representative strain of each of the oral spirochete species T. denticola, Treponema vincentii and Treponema socranskii were differentiated by concanavalin A, phaseolus, lotus A and arachis lectins in a microtiter plate immunoassay for the detection of surface sugars.