A number of metabolic reactions have been shown to occur in microorganisms in recent years, which help to explain their ability to utilize 2-carbon compounds for growth. The central reaction for acetate-grown organisms appears to be the malic synthetase described by Wong and Ajl (1956, 1957) in which a 4-carbon compound, malic acid, is synthesized from acetyl coenzyme A (CoA) and glyoxylic acid. Other adaptive enzymes, such as citritase (Dagley and Dawes, 1953; Gillespie and Gunsalus, 1953) and isocitritase (Campbell, Smith, and Eagles, 1953; Smith and Gunsalus, 1954, 1957), are found in acetate-grown organisms. Kornberg and Krebs (1957) have proposed the name "glyoxylic acid by-pass" for the isocitritase-malic synthetase enzymes acting in concert to provide carbon substrates feeding into the tricarboxylic acid cycle. Nonetheless, this may be only one of a number of ways in which acetate-grown organisms synthesize larger carbon compounds. Glasky and Rafelson (1959), measuring the incorporation of C14-acetate into various compounds by a method similar to that of Calvin and co-workers (1950), have found that succinate is formed prior to malate and isocitrate in the Crookes strain of

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Protoplast membranes from Streptococcus pyogenes incorporated rhamnose into a preexisting polysaccharide when incubated with thymidine diphosphate rhamnose-C(14). This polysaccharide, when extracted from the membranes, did not give a precipitin reaction with group A antisera, but could be coprecipitated with added group A polysaccharide by acetone. It is presumed to be a precursor to group specific polysaccharide of the streptococcal cell wall.

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