Abstract: Objective:?To study the effects of heme concentration on the pathogenic potential of P. gingivalis in C. albicans - P. gingivalis dual-species biofilm. Methods:?P. gingivalis-C. albicans dual-species biofilm and P. gingivalis single-species biofilm were established in a low- and high- heme environment. The living and dying status of microorganisms in biofilms was observed by laser confocal microscope. Trypsin-like proteinase (TLP) activity of P. gingivalis in culture supernatant and cells was determined by standard curve. The drug resistance of P. gingivalis was detected by K-B disk agar diffusion method. Results:?Under the condition of low heme culture, the number of viable P. gingivalis in the dual-species biofilm was significantly higher than that in the single-species biofilm, and as well as the thickness of the dual-species biofilm was wider in 3D images. The TLP activity in the supernatant and cell of P. gingivalis in dual-species biofilm was higher than that in single-species biofilm (P<0.05). In addition, the resistance rates of P. gingivalis in the dual-species biofilm against cefazolin and ciprofloxacin were also increased, while they were sensitive to sulfamethoxazole. There was no significant differences in Live/Death rate, TLP activity and drug sensitivity between the dual- and single-species biofilm under high heme culture condition, but the TLP activity and the resistance against cefazolin and ciprofloxacin were lower than those of the biofilms cultured in a low-heme environment. Conclusions:?Under the condition of low heme culture, the pathogenicity potential of P. gingivalis in the dual-species biofilm was increased.

Key words: Porphyromonas gingivalis, heme, Candida albicans, pathogenicity potential, periodontitis