The Research About Effects Of Pseudomonas Aeruginosa On Candida Albicans Biological Activity In Vitro And The Change Of Hyphae-specific Gene Expression

Objective To explore the effects of Pseudomonas aeruginosa(PA)on Candida albicans(CA)ATCC90028 morphology transition and biofilm formation in vitro,and learn more about some of the hyphae specific gene(ALS3 HWP1 ECE1 HGC1)expression.Methods Bactericidal test were applied to search for inhibitory effects of 50 PA clinical isolates on CA survival on plates.Studying the influence on CA phenotypic switching when co-culture with 3 supernatants from obvious inhibitory and no inhibitory PA isolates,respectively,under inverted microscope after 6 hours.Adding of LB liquid medium as control.Adding twice the original concentration of PA supernatants 100 ml to hyphae promoting culture RPMI-1640 100 ml,The biofilm development of CA after 24 hours co-culture was measured using a semiquantitative reduction assay(MTT)in 96-well polystyrene plates.Adopting fluorescence quantitative reverse transcription PCR(rt-q PCR)method,extracting total RNA in CA and reversing transcript to c DNA,then amplifying the target genes,the data analysis using 2-??CTmethod,to understand relative expression of hyphae-specific genes under the different PA supernatants compare with the control group.Results19 of total 50 PA strains appeared obvious inhibition zone against fungi(19/50)whereas the zone diameters were distinctly different,and was related to the expression of pigment from PA.Only the supernatants from positive-zone PA isolates can inhibit the CA morphological switching under inverted microscope after 6 hours,no hyphae can be seem but the yeast and germ;The experiment of other 3 negative-zone PA isolates were not see any obvious different compare wih control group.As well as the supernatants from positive-zone PA isolates can obstruct biofilm development(p<0.01),one of the supernatants from negative-zone PA isolates can also obstruct development of biofilm(p<0.05).In the assay of rt-q PCR,most of the supernatants can obviously inhibit the expression of hyphae-specific genes(ALS3?HWP1?ECE1?HGC1)except one of them have no statistical significance to the expression of gene HWP1 and ECE1,the level of inhibition ranged from 1/50 to 1/2 differently.Conclusion A part of the supernatants from PA clinical isolates can efficiently inhibit CA early morphology switching as well as biofilm development in vitro.Most of the supernatants can dramatically inhibit the expression of hyphae-specific gene although the level of inhibition apparently different.