Effect of Carbon Nanomaterials on Biofilm Formation and Morphometric Characteristics of the Cells of Alcaligenes faecalis, a Typical Member of the Activated Sludge Microbial Community

The effect of single-walled carbon nanotubes (SWCNTs) and graphene derivatives on biofilm formation, metabolic activity, and morphometric characteristics of Alcaligenes faecalis 2 cells was studied. It was found that in the cultivation medium, graphene derivatives caused a 30–40% decrease in biofilm biomass and metabolic activity of A. faecalis 2 cells, without complete suppression of their metabolism or biofilm formation inhibition. In the cultivation medium, SWCNTs and SWCNTs-COOH significantly enhanced the biofilm formation by A. faecalis 2. SWCNTs modified with octadecylamine caused morphological changes and lysis of some of the cells. The pro-biofilm activity of SWCNTs was due to the adaptive response of bacterial cells to the presence of nanocarbon in the medium, which damages the cells.