Treponema denticola transcriptional profiles in serum-restricted conditions

Treponema denticola is a major pathogen in periodontal disease, frequently isolated from lesions of chronic periodontitis. The ability to adopt its environment is believed to be important for T. denticola in colonizing and proliferating in the gingival crevice. T. denticola use serum as a major nutrient source in the gingival crevices, suggesting that this microorganism utilize serum components to proliferate in gingival crevice. The purpose of this study was to identify T. denticola serum utilization genes. Precultured T. denticola were suspended in tryptone-yeast extract-gelatin-volatile fatty acids medium containing 0, 1 and 10% serum, and incubated anaerobically for 17 h. Total RNA was isolated and T. denticola gene expression was compared by microarray and reverse transcription-polymerase chain reaction. In serum-depleted conditions, the expression of a potential hydroxylamine reductase, several ABC transporters, and phosphoenolpyruvate synthase were increased, while methyl-accepting chemotaxis proteins and a transcriptional regulator were decreased. The results suggest that T. denticola may uptake serum components via ABC transporters. Decreased dmcA expression with decreased serum concentration suggests its involvement in chemotaxis toward serum-rich environments. Comparison of 3 culture conditions. Treponema denticola was cultured in medium containing 10%, 1% or 0% for 17 h. Profile of gene expression of T. denticola grown in medium containing 1% or 0% serum was compared to that grown in medium containing 10% serum.