Hydrophobic interactions within biofilms of nitrifying and denitrifying bacteria in biofilters

Hydrophobicity of the solid surface and microbial cell surface is important factor for the development of biofilms applied in bioengineering systems. An adsorption of phenanthrene was used for analysis of the hydrophobicity o f support fibers and bacterial cell surfaces within the biofilter of wastew ater. The adsorption of phenanthrene was measured by synchronous fluorescen ce spectrometry. Cell surface hydrophobicity does not depend on the fixatio n procedure, pH of microbial suspension, and has no clear correlation with an adherence of the cells to hexadecane droplets. Notwithstanding high hydr ophobicity of bacterial cells, the hydrophobicity of intact biofilm is dete rmined by the hydrophobicity of the support fibers. New indexes were propos ed to evaluate the reactor performance related with hydrophobic interaction s within the biofilm. These indexes showed that significant share of hydrop hobic sites within the nitrifying biofilm is protected from the hydrophobic interactions between the cells and environment.