Method: Culture supernatants were analyzed for the AbpA protein using a ligand-binding assay when S. gordonii was grown in chemically defined medium supplemented with 1% starch, 0.5 mg/ml amylase, starch and amylase together, and various linear maltooligosaccharides. Expression of the abpA gene was also tested by relative qRT-PCR.
Result: AbpA was undetectable in the supernatants of cultures containing starch alone or amylase alone. However, in the presence of both starch and amylase the amount of AbpA protein was notably increased. Transcription analysis of abpA revealed a significant increase in abpA gene expression (p < 0.05) after 40 minutes incubation in chemically defined medium supplemented with starch and amylase. Similar results were obtained in cultures in the presence of several short chain maltooligosaccharides.
Conclusion: These results suggest that the products of starch hydrolysis from the action of salivary α-amylase play a regulatory role in AbpA expression by S. gordonii.
Keywords: Bacterial, Biofilm, Microbiology, Plaque and Saliva