title: Immobilization of bacteria in silica matrices using citric acid in the sol-gel process.
abstract: The aim of this work was to use citric acid in the sol-gel process to generate an inorganic polymer that allows bacterial survival for long periods of time and to study the influence of different storage temperatures. We compared gram-negative Escherichia coli and gram-positive Staphylococcus aureus, immobilized and preserved at different storage temperatures in silica matrices prepared by the method proposed. Immobilized E. coli and S. aureus in silica matrices were stored in sealed tubes at 20, 4, -20, and -70 degrees C for 4 months during which the number of viable cells was analyzed. Results show that the immobilization in silica matrices using citric acid, to neutralize the alkalinity of the silica precursors, makes the technique not only biocompatible but also easier to perform since polymerization does not occur immediately as it does when hydrochloric acid is utilized.
authors.affiliation: Cátedra de Química Analítica Instrumental, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956 Piso 3, 1113, Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Gisela S
authors.initials: GS
authors.lastname: Alvarez
authors.forename: Martín F
authors.initials: MF
authors.lastname: Desimone
authors.forename: Luis E
authors.initials: LE
authors.lastname: Diaz
mesh_terms: D001709:Biotechnology / Q000379:methods*; D018914:Cells, Immobilized; D019343:Citric Acid / Q000737:chemistry*; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000502:physiology*; D005615:Freezing; D050296:Microbial Viability; D044367:Phase Transition; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
chemical_list: D019343:Citric Acid; D058428:Silica Gel; D012822:Silicon Dioxide