THE discovery of glutamine as a growth factor for Streptococcus haemolyticus [MDlclwain et at. 1939] and the occurrence ofhydrolytic and synthetic glutaminase in those animal tissues, kidney and liver [Krebs, 1935] which contain the most active deaminases [Krebs,. 1933], suggested that glutamine might play a part in the metabolism of amino-acids by streptococci, possibly as a carrier of labile NH3. It was considered desirable .therefore to examine the deamination of amino-acids by the organism since no interest has been shown in this field, though a soluble protease has been extracted by Stevens & West [1922]. Foster [1921] showed that NH, was liberated coincidently with disappearance ofNH,-N during the period of most active growth on glucose-broth or glucose-serum-broth, though subsequently NH2-N reappeared without disappearance ofNH3. This was assumed to be due to continued proteolysis without fuirther utilization of aminoacids. Out of 101 substrates tested as H-donators to indigo-tetrasulphonate, 71, including theamino-acids,werefound by Farrell [1935] to be inactive. The present work reconciles these findings, since it is shown that out of 22 c-amino-acids only arginine yields significant amounts of NH.3 and the reaction is not oxidative but 1. Str. haemolyticws. Richards. Group A from Dr L. Colebrook. 2. Str. haemolyticus. Kenny. Group B from Dr L. Colebrook. 3. Str. haemolyticus. N. Morris. Group B from Dr L. Colebrook. 4. Str. haemolyticu8. Batty. Group B from Dr L. Colebrook. 5. Str. viridans. N.C.T.C. No. 3165. 6. Str. faecalis. Freshly isolated by Dr G.
SUMMARY:The nutrition of three virulent and three avirulent strains of Pasteurella pestis has been studied at temperatures between 23 and 37" on a basal medium containing glucose, ammonium and other inorganic salts. The organism has considerable synthetic powers and the distinction between essential nutrients and non-specific stimulants of growth is not always definite. At 32" and below, the optimal medium contained phenylalanine, valine, isoleucine, cysteine, methionine and haemin. Five out of the six strains utilized leucine in place of valine, but the maximum count was then delayed. At 36" the optimal medium contained in addition, alanine, leucine, serine, threonine, biotin and pantothenate. Omission of alanine or leucine delayed growth without reducing the maximum population. When biotin and pantothenate were omitted the organism required a mixture of twenty amino-acids.The nutrition of Pasteurella pestis has been studied with conflicting results by Rao (1939, 1940b), Berkman (1942), Doudoroff (1943) and Herbert (1949). Rao (1939), using large washed inocula (c. 107 cells/ml.) at 2 7 ' , claimed that the only amino-acids for which there was a specific requirement were phenylalanine, proline and cystine, but that glycine was stimulatory and a t least two of the four comprising alanine, leucine, lysine and arginine were also required. Metabolic experiments (Rao, 1940 a) showed that arginine and lysine were not appreciably oxidized and these were then omitted from media used for investigating the stimulatory effects of some of the then-known growth factors (Rao, 1940b), but other amino-acids oxidizable by the organism were also added, viz. valine, isoleucine, methionine, serine, tyrosine and glutamate. Doudoroff (1943), working a t 29", claimed that only cystine and phenylalanine were essential on first transfer from blood agar, although proline stimulated two pathogenic strains. A non-pathogenic strain was able to utilize thiosulphate, sulphite, thiolacetic acid or homocystine, but not methionine, in place of cystine. Large inocula were necessary, however. Berkman (1942), using an inoculum of 1-2 x 104 cells/ml. and a temperature of 37", found that four out of five strains grew in 1-2 days on a mixture of 18 a-amino-acids or a gelatin hydrolysate medium, but the fifth strain failed to grow under these conditions. Using a similar medium containing 20 a-aminoacids, Herbert (1949), also working a t 37O, found growth to be irregular even with as large an inoculum as lo6 organisms/ml., but the addition of haemin led to consistent growth from as few as 10 cells/ml.Rao (1939) and Doudoroff (1943), working below 30" in the neighbourhood of the recognized optimum temperature, agree in claiming simpler nutritional requirements than those observed at 37' by Berkman (1942) and Herbert (1949). The observations of the two former authors are of little value, however, owing to the use of large inocula. It was considered desirable therefore to
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.