GROWTH STIMULATING EFFECT OF AUTOCLAVED GLUCOSE MEDIA AND ITS RELATIONSHIP TO THE CO 2 REQUIREMENT OF PROPIONIBACTERIA

206

101

When Myxococcus xanthus FB was grown on 0.2% casein it exhibited a phenomenon we call cooperative growth. That is, above 104 cells per ml, both strains that were studied exhibited increasing growth rates as a function of increasing cell numbers. Between 104 and 107 cells per ml, the mean doubling times of strains YS and TNS decreased from 15.2 to 8 h and 26 to 8.5 h, respectively. The extracellular proteinase activity of the two strains was equivalent and directly proportional to cell number. Cooperative growth was correlated with increased concentration of hydrolyzed casein in the medium, suggesting cooperative hydrolysis of casein. At low cell densities neither strain was capable of measurable growth on casein in liquid media, and we have calculated that the average concentration of hydrolyzed casein in the medium was indeed too low to support growth. At low cell densities, growth on hydrolyzed casein (Casitone) was normal and independent of cell concentration. Demonstration of cooperative growth at higher cell densities supports the suggestion that the communal behavior of myxobacteria results in more efficient feeding.

Section: Discussionmentioning

confidence: 99%

Cell density-dependent growth of Myxococcus xanthus on casein

Rosenberg¹,

Keller²,

Dworkin³

1977

206

101

“…The properties of the Watson-Reid medium, namely, the importance of low pH and the effects arising from autoclaving, require further comment, for it is possible that the compound(s) formed during autoclaving may in part be responsible for the circumvention of the mycobactin requirement. With regard to growth stimulation by breakdown products of glucose, the fastidious M. paratuberculosis is analogous to organisms belonging to species of lactobacilli (Snell, Kitay, and Hoff-Jorgensen, 1948;Rogers, King, and Cheldelin, 1953;Ramsey and Lankford, 1956), streptococci (Smiley, Niven, and Sherman, 1943;Rabinowitz and Snell, 1947), propionibacteria (Field and Lichstein, 1958), and the genus Bacillus (Sergeant, Lankford, and Traxler, 1957;Lankford, Kustoff, and Sergeant, 1957). As indicated, it is indeed possible that the very slow growth of M. paratuberculosis on filtered media at pH 5.5 can be accomplished only because the essential growth-stimulating factor(s) is formed very slowly during incubations at 37 C. Speculation regarding the function of the autoclave factor(s) for M. paratuberculosis must await chemical definition of the factor(s) itself.…”

Section: Discussionmentioning

confidence: 99%

Circumvention of the Mycobactin Requirement of Mycobacterium paratuberculosis

Morrison

1965

Circumvention of the mycobactin requirement of Mycobacterium paratuberculosis. J. Bacteriol. 89:762-767. 1965.-The mycobactin growth requirement of Mycobacterium paratuberculosis was circumvented on glucosecontaining synthetic medium with an initial pH of 5.5. Mycobactin was required during the first transfer on the synthetic medium. Subsequent transfers have grown in the absence of mycobactin. The growth of mycobactin-"independent" strains of M. paratuberculosis on the synthetic medium was found to be stimulated by low concentrations of mycobactin. The circumvention of the mycobactin requirement appears to depend upon the properties of the medium and not upon having created conditions which promote endogenous mycobactin synthesis. Investigation of the glucose-containing synlthetic medium showed that: (i) growth stimulatory compounds were formed during autoclaving, and (ii) compared with neutrality a pH of 5.5 gave markedly increased pellicle yields. It was suggested that the growth-stimulatory compounds formed during autoclaving may in part be responsible for the circumvention of the mycobactin requirement.

“…Stimulation by glucose autoclaved in media was equally strong with the strains utilizing glucose and the strains not utilizing glucose. Consequently, the growth stimulation must be attributed, not to the glucose, but to derivative products when glucose was autoclaved in the media as little as 5 min at 121 C. Such an effect has been reported previously (4,13,14,16,28), but it is difficult to identify these mediating substances because of the great multiplicity of possible products (3,11).…”

Section: Downloaded Frommentioning

confidence: 91%

Acidaminococcus gen. n., Acidaminococcus fermentans sp. n., Anaerobic Gram-negative Diplococci Using Amino Acids as the Sole Energy Source for Growth

Rogosa

1969

100

Acidaminococcus gen. n. and the type species Acidaminococcusfermentans sp. n. were described. Amino acids, of which glutamic acid is the most important, could serve as the sole energy source for growth. Acetic and butyric acids and CO2 were produced; propionic acid and hydrogen were not produced. Amino acid media supporting growth and the amino acid and vitamin requirements were described. Glucose was frequently not fermented or was weakly catabolized. Derivative products from glucose autoclaved in media, but not glucose itself, stimulated or were required for growth in amino acid media. A wide range of polyols and carbohydrates were not attacked. Lactate, fumarate, malate, succinate, citrate, and pyruvate were not used as energy sources for growth. Pyruvate completely suppressed growth. Cytochrome oxidase and benzidine reactions were negative; catalase, indole, acetyl methyl carbinol, and H2S were not produced; nitrate and sulfonthalein indicators were not reduced; ammonia was produced; gelatin liquefaction was negative or slow and partial; vancomycin (7.5 ,Ag/ml) was resisted. Acidaminococcus was different from Veillonella in morphology, serology, nutrition, utilization of substrates, and accumulation of products in media supporting growth; Acidaminococcus resembled Peptococcus in utilization of glutamic acid and accumulation of similar products, but the two genera differed in morphology, gram reaction, serology, guanine plus cytosine content of deoxyribonucleic acid, and nutrition. Fuller (6) isolated 49 strains of gram-negative anaerobic cocci from the pig alimentary tract. In some cursory morphological and physiological respects, particularly in their reported inability to ferment carbohydrates, polyols, and lactate, these strains appeared to resemble some Veillonella, as