QUANTIFICATION OF THE FEULGEN REACTION IN BACTERIA

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Abstract
A study was made to evaluate some of the factors which might influence the Feulgen reaction. The need for a fully quantitative Feulgen test was indicated by a superficial survey of several strains of bacteria with a semi-quantitative tube test. The results suggested that some of the variation of the microscopic Feulgen reaction depended on age of the culture, the type of substrate, and the species. A quantitative test tube Feulgen method was based on extraction of Feulgen stained material from bacterial cells with 5% perchloric acid. Quantification of the reaction made possible the use of more significant tests of its specificity than were possible with a qualitative method. Evidence indicated that lipids did not contribute significantly to the color under the conditions used. Desoxyribonuclease treatment decreased the Feulgen value. A high correlation (r = 0.95) was observed between the Feulgen value and the diphenylamine test for desoxyribonucleic acid. Some observations on behavior of Azotobacter agile, as well as other microorganisms toward the Feulgen reaction are presented.