Fluorescent bacteria encapsulated in sol-gel derived silicate films

Recombinant fluorescent E. coli cells were encapsulated in sol-gel derived silicate films. Green and red fluorescent proteins expression by recombinant E. coli strains within the silicate film were studied. The effect of the preparation protocol on the viability of the encapsulated cells and their ability to express the fluorescent proteins in response to genotoxicity stress were evaluated. Confocal microscopy studies revealed a homogeneous distribution of the recombinant cells within the silicate film. We further showed by confocal microscopy studies that the encapsulated cells do not divide within the silicate film. Further, dynamic green fluorescent protein expression studies of a single encapsulated cell were carried out for the first time. No contamination of the surroundings by the encapsulated cells or contamination of the encapsulated culture by the surrounding population of bacteria was observed. The implications of these observations for dual sensing and multistep biosynthesis and biodegradation are discussed.