IDENTIFICATION OF STIMULATORY FACTOR INVOLVED IN SYMBIOTIC GROWTH OF STREPTOCOCCUS LACTIS AND STREPTOCOCCUS CREMORIS.

Dahiya, R. S. (North Carolina State College, Raleigh) and M. L. Speck. Identification of stimulatory factor involved in symbiotic growth of Streptococcus lactis and Streptococcus cremoris. J. Bacteriol. 85:585-589. 1963.-Single-strain cultures of Streptococcus lactis and S. cremoris isolated from a commercial starter culture showed symbiotic growth in milk. This study dealt with identification of the main component responsible for high acid production resulting from the combined growth of these cultures. Paper chromatography and bioautography were adapted to isolate the main stimulatory factor excreted by the slower-growing culture (S. lactis) in the culture media. It was identified as adenine on the basis of ultraviolet absorption spectra and paper chromatographic R(F) value. Pure adenine possessed the same properties and was also stimulatory to the faster-growing culture (S. cremoris) when added to milk.