Effect of Heat Sterilization on Growth-Promoting Activity of Pyridoxine for Streptococcus lactis R

Abstract

In a previous publication 1 the existence of a physiologically active metabolite of pyridoxine which possessed much greater activity for Streptococcus lactis R than did synthetic pyridoxine itself was demonstrated. For convenience this metabolite (or mixture of metabolites) was called “pseudopyridoxine.” It was further shown that the absorption of pyridoxine by this organism from media in which pyridoxine (or a derivative) was in limiting concentration did not occur to a measurable extent. This result is in conutilized by the organism for growth, while most of the pyridoxine present remained unchanged and hence unavailable for growth of the organism. It was not clear why such a conversion process should cease, and growth of the organism stop, while an excess of unchanged pyridoxine was still present in the medium.

Results cited below show that the conversion results not from activities of the test organism, but rather from interaction of pyridoxine with certain constituents of the trast to those secured with all other known nutrilites which have been investigated. On the basis of this fact, it was postulated that pseudopyridoxine, rather than pyridoxine, was the physiologically essential factor for this organism. this organism. The growth-promoting activity of pyridoxine, according to this view, resulted from a transformation of a minute amount of pyridoxine to a more highly activeform (pseudopyridoxine), which was then medium during heat. sterilization. It is shown that the activity of pyridoxine can vary greatly, depending upon how long it is autoclaved with the medium.

Experimental. The medium and technic used were exactly similar to those previously described in detail. 1