Colony-forming units or cells in suspension of oral anaerobic spiroche
tes (Treponema denticola, Treponema vincentii and Treponema socranskii
) bind hemin and Congo red. Hemin or Congo red binds to a hydrophobic
polypeptide receptor that is located in the outer membrane of the bact
erial cells and it has a relative molecular mass of 47 kDa. These oral
spirochetes also lyse sheep erythrocytes to produce beta-hemolytic zo
nes around colony-forming units. The oral spirochetes may acquire iron
for growth when they lyse erythrocytes and bind heme from which they
may sequester and transport iron into the cells.