Anaerobic enhancement of protease secretion by periodontal Candida albicans strains

Abstract

OBJECTIVES: This study evaluated the secretion patterns of aspartyl-protease (Sap) by periodontal and non-periodontal Candida albicans strains in normoxic and anoxic conditions. METHODS: Ten non-related periodontal and other ten non-periodontal C. albicans strains were planktonically grown under normoxic and anoxic conditions in protease-inducible broth. Sap activities were quantified in supernatants using azoalbumin as substrate. One unit of Sap activity was defined as the amount of enzyme necessary to increase in 0.001 unit of OD440nm per min of digestion. Protein concentrations of supernatants were spectrophotometrically determined by Coomassie blue method, with BSA as standard. The number of units of Sap activity per milligram of protein was taken as the specific enzymatic activity. RESULTS: All candidal strains, independent from their origin or atmospheric environment, secreted Saps. Non-parametric multiple comparisons among the four subgroups revealed that in anoxic conditions periodontal strains tend to secret significant higher amounts of Sap than in normoxic conditions (p < 0.0001). However, this superior secretion rate is not different from those obtained for non-periodontal strains grown in normoxic or anoxic conditions. CONCLUSION: There is a possibility of adaptation or selection of C. albicans strains by the periodontal microenvironment. This study was supported by grants supplied by Araucaria Foundation (Process 9042), Coordination for the Improvement of Higher Education Personnel (CAPES Process BEX 0559/06-7), and intramural funds from OBU-PPDH-HKU.