Acid-producing capacity from sugars and sugar alcohols among Lactobacillus isolates collected in connection with radiation therapy

Abstract Objective To investigate the acid-producing capacity from sugars and sugar alcohols of oral Lactobacillus collected in connection with radiation therapy (RT) to the head and neck region. Design Lactobacillus were collected from the tongue, buccal mucosa and supragingival plaque in 24 patients before, during, and after RT. The acid-producing capacity of Lactobacillus isolates (n = 211) was analyzed using a colorimetric fermentation test in microtiter plates. Solutions containing 2% sugars (sucrose, glucose, fructose, lactose) or sugar-alcohols (sorbitol and xylitol) were used. After 24 h of incubation, bacterial acid-producing capacity was determined as strong (pH   6). Data regarding intake frequency of sugar-rich products and products with sugar-alcohols was collected. Results The highest acid-producing capacity using the sugars was seen for isolates collected during RT. Sorbitol was fermented to a higher extent during and post RT, especially among isolates from plaque. Lactobacillus fermenting xylitol showed the highest acid-producing capacity during RT (p  Conclusion The results suggest that Lactobacillus isolates, collected from the tongue, buccal mucosa and supragingival plaque, have a higher acid-producing capacity using sugars and sugar-alcohols during RT than one year post RT.