VITAMIN EFFECTS IN THE PHYSIOLOGY OF MICROORGANISMS

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Abstract
Rates of multiplication of Azotobacter chroococcum and Rhizobium leguminosarum show that vitamin B does not stimulate multiplication. Although many more organisms may be present in a culture containing a concentration of a vitamin B preparation as high as 1:10,000 than are present in the control flask, rates of multiplication are the same within the 2 flasks. The greater number of organisms in the one flask results from initial stimulation of multiplication due to small amounts of readily available food material other than vitamin B. On exhaustion of this foodstuff the rate of multiplication is no greater than in the control flask. The meaning of the term vitamin should not be extended, therefore, to include substances necessary for growth and reproduction of microorganisms and certainly not to indicate any substance serving to stimulate their growth or reproduction, but should be restricted to those substances not carbohydrates, proteins, fats, or minerals essential to growth and reproduction of suitable animals.