Streptococci of souring milk with special reference to streptococcus lactis: Studies of the streptococci. IX

Ayers, S. Henry; Johnson, W. Thomas; Mudge, C. S.

doi:10.1093/infdis/34.1.29

Cited by 20 publications

(7 citation statements)

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“…They conform exactly to the characterization of Str. kefir Migula as emended by Evans (26) and to the additional features of that species described by Ayers, Johnson & Mudge (27). Str.…”

Section: Heterofeementative Streptococcimentioning

confidence: 75%

362. Studies in the bacteriology of milk: I. The streptococci of milk

Abd‐el‐Malek¹,

Gibson²

1948

Journal of Dairy Research

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The bacteria that occur in milk have frequently been studied in the mass by making counts of the organisms or by measuring their total chemical activity. Comparatively little attention has been given, however, to the composition of the bacterial populations in different types of milk. It is generally accepted that streptococci are frequently the dominant organisms, and much information is available concerning the coliform group; but for other bacteria and the individual species of streptococci there are few records of the frequency with which they occur. The question whether market milk possesses a special and characteristic microflora, or one that is too variable and heterogeneous to define, cannot be answered by the information at present available. The solution of practical problems in the dairy industry is often impeded by this lack of knowledge; too frequently the only approach must be an empirical one.The object of the present investigation was to provide a clearer picture of the microbic populations in raw and pasteurized milks of varying purity. The general plan of the work was to make quantitative platings and to investigate the organisms that formed colonies. The pure cultures were studied for the purposes of identifying them and of discovering their properties, especially those properties that appeared to be of significance in relation to dairy products. Problems arising during the course of the diagnostic work were investigated with the object of improving methods of recognizing the more frequently occurring organisms. This, the first paper of a series, describes work on the streptococci of milk. Subsequent papers will be concerned with the other major groups of bacteria and with the quantitative relationships of the organisms in different classes of milk. METHOD OF EXAMINING MILKIn selecting milk for examination the intention was to secure specimens varying widely in bacteriological condition. Thus, three main types of raw milk were used: (1) samples obtained by aseptic milking, (2) milk produced under good or fairly good conditions and bottled on the farm, and (3) bulked milk in which heavily contaminated supplies were invariably represented.Samples were examined in the raw state and also after pasteurization in the laboratory at 63° C. for 30 min. They were plated in duplicate on meat infusion agar containing 1 % tryptone peptone and 0-25 % glucose. Each plate inoculated with less than 1 ml. of the sample received an addition of 0-5 ml. of sterile skim milk. Plates were incubated for 5-6 days at 30° C. This combination of medium and incubation was expected to permit the growth of most types of the bacteria occurring in the samples. If this expectation was in fact realized, only the predominant organisms would be obtained from samples giving

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“…They conform exactly to the characterization of Str. kefir Migula as emended by Evans (26) and to the additional features of that species described by Ayers, Johnson & Mudge (27). Str.…”

Section: Heterofeementative Streptococcimentioning

confidence: 75%

362. Studies in the bacteriology of milk: I. The streptococci of milk

Abd‐el‐Malek¹,

Gibson²

1948

Journal of Dairy Research

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“…Although some diversity among different types of lactic streptococci is indicated on the basis of fermentation reactions and certain other characteristics, most workers have considered these only variants from type, or at most varieties, rather than species. (Ayers, Johnson and Mudge, 1924;Hammer and Baker, 1926;Stark and Sherman, 1935;Yawger and Sherman, 1937a.) On the other hand, there have been suggestions, notably by Orla-Jensen and Hansen (1932), that this group of streptococci should be divided into a number of species based upon fermentation reactions.…”

Section: The Lactic Streptococcimentioning

confidence: 99%

“…Quite independent of the work of Orla-Jensen, and uncorrelated with it, is that of Ayers, Johnson and Mudge (1924) who described a unique type of lactic-acid streptococcus as Streptococcus lactis Var. B.…”

Section: Streptococcus Lactismentioning

confidence: 99%

The Streptococci

Sherman¹

1937

Bacteriological Reviews

222

133

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“…A definitive difference between the two "species" was established by a number of workers (5,7,20,35) who showed that some streptococci such as S. lactis hydrolyzed peptone (and specifically arginine) with the production of ammonia, whereas S. cremoris strains lacked this ability. Agar media were subsequently developed (26,28,34) to differentiate S. lactis from S. cremoris on the basis of ability to produce ammonia from arginine; such media are important in selecting strains for use in milk fermentations.…”

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confidence: 99%

Arginine metabolism in lactic streptococci

Crow¹,

Thomas²

1982

J Bacteriol

163

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Streptococcus lactis metabolizes arginine via the arginine deiminase pathway producing ornithine, ammonia, carbon dioxide, and ATP. In the four strains of S. lactis examined, the specific activities of arginine deiminase and ornithine transcarbamylase were 5- to 10-fold higher in galactose-grown cells compared with glucose- or lactose-grown cells. The addition of arginine increased the specific activities of these two enzymes with all growth sugars. The specific activity of the third enzyme involved in arginine metabolism (carbamate kinase) was not altered by the composition of the growth medium. In continuous cultures arginine deiminase was not induced, and arginine was not metabolized, until glucose limitation occurred. In batch cultures the metabolism of glucose and arginine was sequential, whereas galactose and arginine were metabolized concurrently, and the energy derived from arginine metabolism was efficiently coupled to growth. No arginine deiminase activity was detected in the nine Streptococcus cremoris strains examined, thus accounting for their inability to metabolize arginine. All nine strains of S. cremoris had specific activities of carbamate kinase similar to those found in S. lactis, but only five S. cremoris strains had ornithine transcarbamylase activity.

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Streptococci of souring milk with special reference to streptococcus lactis: Studies of the streptococci. IX

Cited by 20 publications

References 0 publications

362. Studies in the bacteriology of milk: I. The streptococci of milk

362. Studies in the bacteriology of milk: I. The streptococci of milk

The Streptococci

Arginine metabolism in lactic streptococci

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