Isolation and identification of growth stimulators of Escherichia coli M-17

The stimulating activity of E. coli M-17 culture fluid (CF) is determined by the action of low-molecular exometabolites, readily soluble in water. The high-molecular fraction was removed from CF by ultrafiltration, the growth stimulators were adsorbed on anion exchange resin and eluated at pH 3.1. In further purification HPLC and chromatography on TSK gel HW-40 were used. The identification of compounds was carried out by the methods of thin-layer chromatography, amino acid analysis and 1H-NMR spectroscopy. Glutamic acid (glutamine) and succinic acid proved to be the most active growth autostimulators. The data of biological testing made it possible to believe that CF also contained less active stimulators and/or synergic substances which had no their own activity, but stimulated growth, acting jointly with other compounds. In view of the definite specificity of action observed in initial CF, some differences in the spectrum of growth stimulators of other E. coli strains may be supposed.