Effect of Graphene Derivatives on Biofilm Formation of Candida maltosa

Graphene derivatives (oxide and its reduced form) are the promising carbon nanomaterials (CNMs) used in industry, electronics, medicine, and biotechnology. The goal of the work was to study the effect of graphene oxide (GO) and its reduced form (rGO) on the formation and destruction of Candida maltosa VKPM Y-194 biofilms, metabolic activity, intracellular ATP content, and the permeability of the cytoplasmic membrane of biofilm cells. It was found that GO and rGO slightly inhibit yeast biofilm formation, and the decrease in biofilm biomass during growth in the presence of GO was more significant than during cell growth with rGO. The destruction of mature 7-day yeast biofilms is slightly greater in the presence of CNMs than in the control, and significantly greater than in 3-day biofilms exposed to CNMs. At the same time, the metabolic activity of biofilm cells assessed based on the reduction of tetrazolium salt (methyl thiazolyl tetrazolium reagent) is significantly higher in 3-day biofilms grown in the medium with rGO and in 7-day biofilms with GO and rGO compared to the control. The content of intracellular ATP in biofilms grown in the presence of CNMs exceeded that in the control but was lower after 4-h of the exposure of mature biofilms grown in a nutrient medium without CNMs. The greatest negative effect on the cytoplasmic membrane of biofilm cells, which was manifested in an increase in its permeability, was observed after 4-h exposure of a 7-day biofilm to GO. It was found that the negative effect of CNMs on biofilms of C. maltosa VKPM Y-194 is more pronounced when exposed to GO than to rGO and higher with exposure of 7-day biofilms than 3-day. Complete inhibition of biofilm formation and complete eradication of mature biofilms when exposed to CNMs have not been observed.