Sol-gel applications in environmental biotechnology.

Sol gel process was applied for three different applications in environmental biotechnology: (1) thin, fluorescein diacetate-doped sol-gel film made possible epifluorescent microscopic examination of adsorbed Escherichia coli CN13 cells without additional staining: (2) Thiobacillus thiooxidans cell-free extract entrapped into sol-gel matrix displayed oxidative activity on H2S in liquid medium; and (3) two media (E. coli (EC) and sulfate-reducing bacteria (SRB)) were doped into sol-gel and used to enumerate environmental samples for E. coli and sulfate-reducing bacteria, by the most probable number (MPN) method. The comparison of the modified method with the standard enumeration method revealed very good correlation. The sol-gel MPN method is sensitive, saves times, and the substrate can be prepared and stored long-term at room temperature (up to 1 year).