BDSF Inhibits Mycelial Growth Of Candida Albicans

Candida albicans is a very important opportunistic human pathogen. C. albicans is a commensal fungus that harmlessly inhabits various niches of the human body, including the oral cavity, gastrointestinal tract, vagina and skin of healthy individuals. However, among the patients who have been immunocompromised by infection of HIV, HBV or diabetes, C. albicans can cause infection, or candidiasis, which can range from superficial mucous membrane infection to life-threatening systemic disease. This organism has a number of virulence traits, one of which morphogenic switch from a yeast state to a hyphal state is very important.BDSF originates from Burkholderia cenocepacia. BDSF is structurally similar to the diffusible signal factor (DSF) that is produced by the RpfF enzyme of Xanthomonas campestris. Bcam0581, which encodes an RpfF homologue, was essential for BDSF production. The gene is highly conserved and widespread in the B. cenocepacia. Exogenous addition of BDSF restored the biofilm and extracellularpolysaccharide production phenotypes of X. campestris DSF-deficient mutants.In this thesis, morphologically, we firstly tested whether BDSF inhibits the hyphae growth of C. albicans from yeast state; then, we checked whether BDSF accelerates the transition from hyphae state to yeast state. During these experiments, we chose GS medium as the hyphae-induced medium which has a modest ability of inducing the hyphae growth of C. albicans. When Candida albicans was incubated in GS medium, it is after3hours that the medium could translate more than90%yeast into hyphae and after4hours that it could translate more than95%yeast into hyphae. So the GS medium is the ideal choice.Results demonstrated that BDSF can strongly inhibit the hyphae growth of C. albicans when the concentration≥30μM. Once the hyphae was formed, at the concentration of30μM and60μM, BDSF could not inhibit the further growth and branch of the formed hyphae, but it could transform the new-born hyphae into yeast state, however, the formed hyphae remained what it was; At the concentration of120μM, BDSF nearly inhibited the hyphae growth of C. albicans.