- Volume 29, Issue 2, 1962

SUMMARY: Hydrolysates of the cell walls of 26 strains of group A streptococci were examined by paper chromatography. In all cases lysine, glutamic acid, alanine, glucosamine, muramic acid and rhamnose were found as the principal components. The mean relative proportion of lysine: glutamic acid:alanine was 1.1:1:4. Thus even when a number of strains of a particular bacterial species was tested, there was good uniformity in the cell-wall composition. Samples of cell-wall material which remained undigested after treatment with proteolytic enzymes all contained small amounts of several amino acids. It seems probable that a small amount of polypeptide or protein remained firmly attached to the cell walls examined.

SUMMARY: The paper deals with the relationship betweeen the water content of washed Serratia marcescens and the thermodynamic activity of water, a w, over the range 0 < a w < 1.0. Two overlapping types of measurement are used: osmotic water exchange and water-vapour sorption. The data are given in terms of the equation w = Bm −r where w is water content, m is external osmolality (actual or effective, depending upon the technique used), B is a constant and r has values which can be interpreted in terms of the type of process involved: e.g. in the initial stages of osmotic dehydration, r of unity would indicate ideal solution behaviour; in the final stages of drying, any constant value of r would conform to an adsorption function like that of Halsey (1948). The data obtained by the two techniques used fall on a single curve with several zones including (a) non-ideal solution behaviour at high a w, (b) two intersecting ‘co-operative adsorption’ zones at very low a w, and (c) a region of variable r where processes such as dissolution of small molecules and ‘saturated’ swelling of interlinked polymeric structures are presumed to occur. It is thought that detailed interpretation of the unified water uptake curves would be valuable in understanding mechanisms of humidity-dependent loss of viability, in particular the zones of exceptionally rapid attenuation.

SUMMARY: There were found considerably fewer biochemically active microorganisms among heterotrophs inhabiting the equatorial-tropical zone of the World Ocean than in the high latitude area. Many micro-organisms with many-sided enzymic activities were present in the microbial population of the near-polar area, determining more profound transformations of organic matter in the waters of these areas as compared with the tropical area and consequently an increased concentration of biogenic substances. It is suggested that there is a unique exchange between the areas of low latitudes and those of high latitudes in the World Ocean. Currents driving equatorial-tropical waters to the north and south carry with them organic matter, chiefly allochthonous in origin; this material is more completely decomposed by the microbial species which inhabit high latitudes. The liberated biogenic substances are carried by currents into the depths of other geographic areas, thus increasing the reserve of substances taking part in the primary production of organic matter in these areas of the World Ocean.

SUMMARY: Samples of populations of Aerobacter aerogenes grown in continuous culture on a limited supply of glycerol died linearly with time without significant cryptic growth when aerated in buffered physiological saline at their growth pH and temperature. Death was uninfluenced by atmospheres varying from pure O2 to 2% O2 in N2 but was accelerated under N2 in media of various Eh values. Death was accelerated in environments of higher or lower tonicity, in unbuffered media, at pH values above 7, temperature above 40°, by strong illumination. Within limits, lower pH values or temperatures prolonged survival. Death was not immediately accompanied by breakdown of the osmotic barrier. Populations more dense than equiv. 20 μg. dry wt./ml. survived longer, sparser ones died more rapidly. The death rates of the populations studied were not influenced by 30% i-erythritol or by certain high molecular weight materials. Several metabolic inhibitors were tested; most of them accelerated death or had no effect; three protected transiently. Mg2+, Ca2+ or Fe3+ ions delayed death. A variety of trace elements, inorganic ions, growth factors, or an amino acid mixture, had no significant action; glycerol or intermediate compounds accelerated death. Dying populations showed rapid initial breakdown of intracellular RNA with release of phosphate and base fragments into the medium; most of the ribose was metabolized. Intracellular protein was degraded after a lag; intracellular polysaccharide and DNA were scarcely degraded at all. Endocellular reserves declined much more rapidly than did viability; the with glycerol and ‘glycerol dehydro-genase’ activity declined in parallel with viability. Populations permitted to grow at different rates died more rapidly the slower the growth rate; steady states were obtained by slow continuous culture in which constant proportions of the organisms were dead.

For a given growth rate the nature of the limiting nutrient influenced the form of the survival curve: carbon, phosphorus, sulphur or oxygen limitations gave almost linear curves, N-limitation gave a sigmoid curve and Mg-limitation a concave form. In some instances the growth rate influenced the form of the survival curve and the death rate; Mg-limited organisms apparently died faster the faster they grew. The survival of stationary phase populations derived from batch cultures depended markedly on which chemical component of the environment limited growth; ‘logarithmic phase’ and ‘stationary phase’ C-limited organisms differed insignificantly in death rates. Partially synchronized populations from batch cultures died marginally more rapidly when harvested just after division ceased.

SUMMARY: Fluorescent antisera to strains of small Selenomonas ruminantium var. lactilyticas grown in vitro from sheep rumen contents appeared to react specifically with some of the large selenomonads seen in vivo in rumen contents. It seems probable, therefore, that the selenomonads isolated by the usual cultural methods are those seen in rumen contents.

SUMMARY: Some of the recorded properties of a filterable organism (the PAP organism) isolated by Eaton and colleagues from cases of human primary atypical pneumonia suggest that it may be related biologically to the Mycoplasma (pleuropneumonia-like) group. In further investigation of this possibility now reported it was found that the organic gold salt, sodium aurothiomalate, which is known to inhibit certain mycoplasmas, would also inhibit infection with the PAP organism in the hamster and chick embryo lung. Some accepted viruses of a similar order of size to the PAP organism —namely, Nigg’s pneumonitis virus of mice (psittacosis group), three strains of influenza virus A, vaccinia and variola viruses—were not inhibited by sodium aurothiomalate. On the other hand, grey lung virus of mice, an organism with some properties resembling those of the PAP organism, was strongly inhibited. Diethyl ether and the antibiotic kanamycin sulphate both inhibited the growth of the PAP organism in chick embryo lung. An intensified Giemsa-staining method revealed small red-purple coccobacillary bodies (later called elementary bodies, EB) in the lungs of chick embryos infected with three different strains of PAP organism isolated, respectively, in 1944, 1954 and 1960 in different parts of the United States. The EB were not seen in uninfected chick embryo lungs. The EB and the antigen of the PAP organism stained by the fluorescent antibody technique occupied essentially the same position in relation to the mesobronchial epithelial cells of chick embryo lung. The formation of both was suppressed in parallel by treatment of inoculum or eggs with diethyl ether, kanamycin sulphate or sodium aurothiomalate. There was a good but not absolute correlation between the presence or absence of EB and antigen in experiments on the growth or survival of the PAP organism in chick embryos, in cell-free media, and in titrations in eggs.

SUMMARY: In addition to R outgrowths, strains of Lactobacillus casei growing on a carbohydrate-free medium also formed smooth secondary colonies situated on the primary colonies. These secondary colonies arose after about 6 days of incubation and were of two types: when centrally situated they formed papillae; when near the margin of the mother colony they often spilt over and formed fan-shaped outgrowths adjacent to the parent colony. Cultures of several different species of Lactobacillus were examined; secondary colony formation was confined almost exclusively to strains of L. casei. The fan-shaped outgrowths were pure cultures of organisms possessing a shorter generation time than those comprising the mother colony. An inverse relationship existed on crowded and sparsely inoculated plates between numbers of papillae and fan-shaped outgrowths/colony observed. The distribution of colonies bearing different numbers of secondary colonies did not follow a Poisson distribution; the random origin of fast-growing variants could not be established. On subculture the fast-growing variants produced colonies with a slightly different morphology from that of the wild-types. This difference was stable and persisted through numerous subcultures. In the presence of small quantities of fermentable carbohydrates secondary colony formation was not observed and this possibly explains how the wild type competes successfully with fast-growing variants in natural environments.

SUMMARY: Micrococcus denitrificans is capable of carrying out assimilatory and dissimilatory nitrate reduction, though only the assimilatory process occurs under both aerobic and anaerobic conditions. Aeration affects the dissimilatory activity (reduction of nitrate to nitrogen) of a growing culture in at least three ways: (a) it prevents the adaptive formation of the system, (b) it partially represses any further synthesis if the system is already present, and (c) it inhibits the activity of the preformed system completely. To some extent these effects of oxygen are reflected in the control which it exerts upon the organism’s content of nitrate reductase (the enzyme responsible for the initial reduction of nitrate to nitrite) and upon its activity during growth.

Ammonium ions partially inhibit the transformation of nitrate into cell nitrogen but have no detectable effect on the nitrate reductase activity of crude extracts of this organism.

SUMMARY: Differences in behaviour of Thiobacillus thioparus, T. denitrificans and T. thiocyanoxidans were found in growth experiments carried out in thiosulphate or thiocyanate containing media and using aerobic or anaerobic conditions. These differences were: T. denitrificans and T. thioparus grew anaerobically in thiosulphate + nitrate and thiocyanate + nitrate media; T. thiocyanoxidans did not. During growth of T. thioparus in thiocyanate + nitrate medium, nitrite accumulated but thiocyanate was not completely oxidized; no nitrite accumulated during growth of T. denitrificans under similar conditions. After aerobic, serial subculture in thiosulphate medium T. denitrificans no longer grew anaerobically in thiosulphate + nitrate or thiocyanate + nitrate media whereas T. thioparus did. T. thioparus produced copious growth on thiosulphate agar slopes under aerobic conditions; T. denitrificans proved difficult to culture under such conditions, i.e. there was a failure to guarantee growth on each occasion, and where growth occurred this was poor. T. denitrificans did not produce the mucoid slime associated with T. thioparus cultures. T. thioparus accumulated and subsequently used up tetrathionate during aerobic growth in thiosulphate medium; T. denitrificans did not.

SUMMARY: Mutant staphylococci with impaired respiration, induced by ultraviolet radiation, were used for testing various inhibitors with already known mechanisms of action. Inhibitors of protein synthesis (the tetracyclins) affected the growth of parent and mutant cultures to the same degree. To the inhibitors of cell-wall synthesis (the penicillins) mutant staphylococci were more resistant than the parents; this was related to the altered amino acid composition of cell-wall material in the mutants. On the other hand, the mutants were much more vulnerable than parents to the action of inhibitors which affected the nucleic acids—namely, mitomycin C (x 50 times), actinomycin C (x 50). trypaflavine (x 300), nitrogen mustards (x 10-20). A specific thymine synthetase inhibitor (5-fluorodeoxyuridine) strongly inhibited the growth of parent staphylococci, but did not at all inhibit the growth of mutants. This points to some deficiency in the enzymic mechanism of synthesis of thymine in the DNA of mutants. Experiments with 5-bromodeoxyuridine suggest that the mutant staphylococci lacked the enzymic mechanism necessary for effective incorporation of halogenated pyrimidines into the DNA precursor pool.

SUMMARY: Nutritional experiments were carried out dealing with (1) the utilization of sulphur compounds; (2) the action of different mineral salts and their interaction. The results showed that the species of Phyhium used grew well at 28° buffered with Sorensen’s salt to give an initial pH of 6.5 and incubated for 13 days for Pythium afertile and 10 days for the remaining species. Acid conditions below pH 5.0 and alkaline conditions above pH 8.0 were not tolerated. The best carbon and nitrogen sources are given. The best sulphur sources were Na2S. Na2S2O3, Na2S04. 10 H2O, Na2SO3.7H2O, Na2S2O5.5H2O, K2S2O8, molecular sulphun. DL-methioninee thioacetamide, L-cysteine, sodium thioglycolate, and DL-cystine Factorial experiments were carried out in which the fungi were incubated at 28° for 13--14 days. Statistical analysis of the results showed that under the given conditions optimal growth measured as mg. dry wt. was obtained in liquid media containing glucose, 10.0 g./1.; KCl. 0.5 g.l with varying amounts of K2HPO4, KNO3 and MgSO4. 7H2O for the different species specified. There was a balance between K2HPO4 and MgSO4. 7H2O for P. debary-anum and there were significant interactions between the salts above taken two at a time for P. debaryanum and P. ultimum but the interactions for the remaining fungi were more variable. There was interaction between all three salts together for two of the species. P. debarganum is more exacting in its nutritional requirements than the other species.

SUMMARY: The bacteriocinic strain of Escherichia coli known as K235L+OC+ which elaborates colominic acid (poly N-acetylneuraminic acid) possesses a K antigen and has the serotype E. coli O1:K1:HNM in accordance with the Kauffmann-White classification scheme of the enterobacteriaceae. Strains of E. coli with O1:K1:HNM or O2:K1:HNM serotype elaborate a similarly constituted colominic acid. Chemical analysis has revealed that all E. coli with a K1 serotype contain neuraminic acid, but that strains which have other K serotypes do not contain significant amounts of this substance. The nature of the O serotype and the ability to produce haemolysins or bacteriocines are unrelated to the presence of neuraminic acid in the various strains analysed. Thus, the close association between a K1 serotype and colominic acid in E. coli suggests that all strains of this serotype produce colominic acid. Salmonella dahlem, S. djkarta, E. coli O1O:K5:HNM, Group C Neisseria meningitidis 1908 and 1935, and Citrobacter freundii O5:H30 (E. coli 5396/38) contain neuraminic acid as shown by chemical tests. However, the neuraminic acid is firmly bound and polysaccharides containing this material are not readily elaborated. As no serological relationship exists between these strains and strains of E. coli having a K1 serotype, it is concluded that they are non-producers of colominic acid. Thus, bacteria of various genera which contain neuraminic acid have this substance in different chemical combinations.

SUMMARY: L-Cystathionine is rapidly degraded to homocysteine, pyruvate and ammonia by cell-free enzyme preparations of an auxotrophic strain of Escherichia coli which requires pyridoxin, glycine or serine for growth. One molecule of each of the products was formed from each molecule of cystathionine throughout the course of the reaction. The preparation did not form pyruvate from L-serine and L-alanine (which were possible intermediates); it is concluded that the cleavage is a single step reaction. After precipitation with ammonium sulphate and dialysis the enzyme required both pyridoxal phosphate and magnesium ions for full activity, but no dependence on magnesium was found with preparations from another strain. The reaction was inhibited totally by cyanide and cupricions and partially by isonicotinic acid hydrazide and sulphydryl compounds (cysteine, homocysteine, glutathione). An auxotrophic strain of E. coli which grew with methionine or homocysteine, but not with cystathionine, did not contain the enzyme.

SUMMARY: Salmonella cultures in which loss of a major antigenic component resulted in the formation of stable serotypes of simpler constitution, previously were thought to have lost a third flagellar phase. Further study of cultures of Salmonella hamilton, S. worthington, and S. meleagridis of complex constitution indicated that loss of a third phase was not involved but that instead the organisms lost a major antigenic constituent present in both phases of diphasic types and in the single flagellar phase of monophasic types. Attention was drawn to the similarity of their behaviour to that of S. salinatis, S. montgomery, and certain other salmonellae of complex constitution.