Abstract
During the past year two papers have appeared in the Journal of Biological Chemistry, one by Dr. Bachman 1 and the other by Dr. Williams 2 , which postulate the requirement of the water-soluble B vitamine in yeast growth. Both these papers suggest the use of yeast cells as a means for the measurement of vitamine content and present a technique that may be used to that end.
In an earlier number of the PROCEEDINGS 3 we reported on a study of the suitability of the Bachman test for vitamine measurement and some of the difficulties encountered. Since that time we have carried out similar studies of the Williams technique and as a result have devised a method which employs features of both authors but seems to permit of better control and to be at the same time more easily handled than the Williams method. This method is presented herewith, not as a finished product for we are still experimenting with certain details of standardization, but with a view to stimulating criticism and suggestion.
The Bachman test measures the vitamine activity in terms of gas generated; it is really a measure of enzyme activity. This fact makes it difficult to be sure that the stimulus is a growth stimulus or merely an enzyme control in any given test. The Williams test measures the effect of the vitamine in growth of yeast cells and this seems to us a more reliable indicator than the gas production. On the other hand the hanging drop method of Williams makes difficult the control of concentration during incubation and we found the preparation of drops containing single yeast cells far from easy to prepare. We believe that our method obviates both these difficulties while retaining the yeast cell count as an indicator.
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