Phenotypic evaluation of the effect of anaerobiosis on some virulence attributes of Candida albicans.

The current assumption that Candida albicans is a facultatively anaerobic organism has been widely accepted since its recovery from anoxic sites became common. However, the link between anaerobiosis and virulence remains uncertain. This study investigated the differential cell-surface hydrophobicity (CSH) using a hydrocarbon/water partition technique and analysed the differential secretion rates of secretory aspartyl proteases (Saps), esterase, chondroitinase and haemolysins of C. albicans strains recovered from periodontal pockets and non-periodontium-related intra-oral sites. For the enzymic tests, all strains from both sets were grown under aerobic and anaerobic conditions and the harvested cells were inoculated onto suitable normal or pre-reduced culture media in the presence or absence of molecular oxygen, respectively. The results showed that no variations were perceptible for CSH and chondroitinase (P>0.05). The secretion rates of esterase and haemolysins strongly decreased in an anoxic environment (P<0.0001). However, a consistent increment (P<0.0001) in Sap secretion was detected when cultures were grown under anaerobic conditions. Based on these results, it is suggested that the oxygen concentration in the atmosphere surrounding cells exerts a variable influence on the virulence attributes of C. albicans.