QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Yang Lin, A. H. Articles by Williams, W. L. Search for Related Content PubMed PubMed Citation Articles by Yang Lin, A. H. Articles by Williams, W. L.

Growth Factors for Lactobacillus bulgaricus GS¹

Department of Biochemistry, University of Georgia, Athens, Georgia

The study of the nutrition of lactic acid bacteria has led to the discovery or isolation of several new vitamins and growth factors of general nutritional and biochemical interest. The observation that a new strain of Lactobacillus bulgaricus required 2 unidentified growth factors therefore appeared worthy of further research which has yielded the following results: 1) Unidentified growth factors for Lactobacillus bulgaricus GS are widely distributed in natural materials from animal tissues to bacterial cells. 2) Two unidentified growth factors are required by L. bulgaricus GS. The factors were separated by hot, aqueous extraction of liver, yeast, or bacterial cells and precipitation at pH 9. One factor, designated precipitate factor (PF), is precipitated at pH 9; and the second factor, filtrate factor (FF), is soluble at pH 9. The PF has been purified 170-fold by precipitation at selected pH and extraction of dried precipitates with hot absolute ethanol in the presence of acid. The PF is an essential growth factor; the FF is not essential but increases the growth response of the organism to PF 3- to 6-fold. 3) PF activity from liver extract was separated by paper chromatography with 35% ethanol into 3 forms with R_F values 0, 0.7 and 0.8. Two forms were present in yeast and bacterial extracts. The dominant form of PF with an R_F of 0.8 exhibited a blue fluorescence and the fluorescent emission spectrum showed a peak at 433 mµ with excitation at 355 mµ. The ultraviolet absorption maximum and minimum were 266 and 245 mµ, respectively. 4) PF is soluble in acidic, absolute ethanol and slightly soluble in chloroform. It is also soluble in water at pH 2, completely insoluble at pH 9, and diffusible through cellophane. 5) Harman and tetrahydroharman can replace PF activity in tube assays but are not identical with PF. Other indole derivatives, including 3-carbolines, produced little or no growth and some inhibited growth.

² H. M. Yang, in previous publications.

Manuscript received 28 October 1965.