Immobilization of bacteria in silica matrices using citric acid in the sol–gel process
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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°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.
KeywordsCitric acid Escherichia coli Immobilization Preservation Sol–gel Staphylococcus aureus
G.S.A. is grateful for her doctoral fellowship granted by the Agencia Nacional de Investigaciones Científicas y Técnicas. M.F.D. is grateful for his post-doctoral fellowship granted by the CONICET. The authors would like to acknowledge the support of grants from the Universidad de Buenos Aires (UBACYT B055 and B817); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET PIP 02493) and Agencia Nacional de Investigaciones Científicas y Técnicas (BID 1728/OC-AR PICT 14192). L.E.D. is a member of the CONICET Research Counsil. We also wish to thank Professor Rex Davis for language corrections.
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