STUDIES ON A GROWTH STIMULANT FROM CORN STEEP USING LACTOBACILLUS CASEI

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Abstract
Methods for the quantitative assay of a stimulatory growth factor present in corn steep liquor and effective in semisynthetic media were developed. Growth was measured turbidimetrically after 12 and 14 hours incubation. Response curves were for the most part linear between increments of 0.4 and 2 corn steep units. A bioautographic technique was developed using L. casei and a pH indicator added to the medium whereby the presence and location of the stimulant on paper chromato-grams could be determined. The movement on the chromato-gram was accomplished by using a mixture of isopropyl alcohol, NH4OH, and water (3:2:5) with descending solvent flow. All of the activity from corn steep for L. casei in semisynthetic media was extracted in phenol, but only 2 to 3-fold purification was obtained. Corn steep activity was found in water obtained from commercial gluten tanks in unconcentrated steep water and in an aqueous extract of ground corn. The replacement of the effect of the corn steep stimulant by known growth factors was eliminated by measuring the response of L. casei to various concentrations of such factors added to the semisynthetic media. The phenol extract of corn steep was found to stimulate markedly the rate of anaerobic glycolysis by L. casei. The presence of O2 had a definite depressing action on the rate of glycolysis by L. casei. and the corn steep factor did not appreciably stimulate glycolysis under aerobic conditions.

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