Preparation of Silicic Acid Jellies for Bacteriological Purposes

Abstract

FOR the preparation of jellies intended for the cultivation of micro-organisms, agar-agar is generally used. For some purposes., however, it is desirable to have an opportunity of obtaining cultures of bacteria or fungi on inorganic gels to which only known substances are added. Agar-agar is an organic substance varying in composition and containing other organic substances, which may influence the cultivation of bacteria. Attempts have been made to prepare gels, for example, of silicic acid; sodium silicate and hydrochloric acid were used for the purpose1,2,3,4. But this method entails certain difficulties. Instead we have tried to make silica gels for bacteriological purposes from ortho-silicic acid tetra-methyl ester, Si(OCH3)4. When water is added to this silico-compound, silicic acid and methanol are formed, and the solution is transformed into a firm coherent gel as clear as glass. This gel formation was observed by Grimaux5.