Sol–gel encapsulation of bacteria: a comparison between alkoxide and aqueous routes

The viability of bacteria in the presence of sol–gel reagents has been studied in order to define the best experimental conditions for the sol–gel encapsulation of E. coli. The β-galactosidase activity of these bacteria, trapped in sol–gel silica matrices, was then analyzed. Two routes, using alkoxide and aqueous precursors, have been used and compared. It appears that the aqueous route is less damaging than the alkoxide one. Moreover the aqueous silica matrix appears to slow down the lysis of cell membranes when bacteria are aged without nutrient.