Competition for glucose between Candida albicans and oral bacteria grown in mixed culture in a chemostat

The competition for glucose as a growth-limiting substrate between Candida albicans and a mixed community of oral bacteria was investigated. A chemost at was operated under glucose-limiting and glucose excess conditions at a d ilution rate of 0.05/h. A mixed population of oral bacteria was established and after a steady state had been reached the chemostat was inoculated wit h C. albicans. Seven bacterial species Streptococcus sanguis, S. sobrinus, S. mitis, Lactobacillus casei, Veillonella dispar, Eubacterium saburreum an d Fusobacterium nucleatum - were able to establish stable populations under glucose-limiting conditions. The yeast was unable to grow with the bacteri a under glucose limitation. Only three bacterial species, S, sobrinus, L, c asei acid E, saburreum, became established under glucose-excess conditions. C, albicans was also able to become established in the glucose-excess chem ostat and could grow and maintain a steady state in a mixed culture with th ese organisms. L, casei, S, mitis and S, sobrinus had faster glucose consum ption rates than C. albicans. All the bacteria, except for F. nucleatum, ha d maximum specific growth rates higher than C. albicans, The results sugges t that glucose may act as a growth-limiting substrate for C. albicans in th e establishment and growth of the yeast in a mixed community of oral bacter ia.