- Volume 34, Issue 2, 1964

SUMMARY: Spores of Bacillus subtilis were gamma-irradiated (60Co source) and viable counts performed by surface spread and tube dilution methods. Surface spread counts were greater than tube dilution counts by factors varying from 1·57 to 3·90 (aqueous suspensions) and 2·36 to 6·10 (freeze-dried). In 8 cases out of 10 there was no significant difference in the regression coefficients of log % survivors against radiation dose for the two counting methods under identical conditions of irradiation. Freeze-drying from 5 % (w/v) aqueous solutions of glucose, lactose or fructose had a significant protective effect on the radiation resistance of the spores. Freeze-drying from aqueous suspension, or from 5 % maltose had no effect on the resistance.

SUMMARY: A fractionation of sulphur isotopes was found in all metabolic processes investigated except those in which elemental sulphur was the starting substrate for growth of Thiobacillus concretivorus and Chromatium sp. and for reduction by Saccharomyces cerevisiae. Except for polythionates formed during sulphide oxidation by T. concretivorus or Chromatium sp., the products of metabolism were enriched in 32S relative to the starting substrates. The magnitudes of the enrichment differed for different processes and for the same overall process carried out by different organisms. The δ34S values (%0) ranged from -46·0 for sulphide from sulphate reduction by Desulfovibrio desulfuricans to +19·0 for polythionate formed during growth on sulphide by T. concretivorus. Fractionation during sulphate reduction was inversely proportional to rate of reduction when lactate and ethanol were electron donors and directly proportional with molecular hydrogen as the electron donor. Temperature and sulphate concentration, within the normal physiological ranges of these parameters, influenced fractionation only in so far as they influenced rate of reduction. However, anomalous fractionation effects were obtained at low temperatures and when a resting suspension reducing sulphite was subjected to changes in temperature. The data are discussed with reference to the mechanism(s) of fractionation.

SUMMARY: Lactate oxidation during sulphate and sulphite reduction by growing or resting Desulfovibrio desulfuricans resulted in an enrichment of 12C in the CO2 released and also in the cell carbon during growth. The enrichments observed varied between δ13C --5·5 to --12·8 %0. With sulphite as the oxidant, the fractionation appeared proportional to rate of metabolism of lactate; no definite rate effect on fractionation was suggested by the limited data obtained with sulphate as oxidant.

SUMMARY: Reported sedimentation coefficients of bacterial ribosomes display noticeable variation. Since this might be due to differences in experimental conditions or to actual differences amongst the bacteria this problem needed re-investigation. The sedimentation coefficients of ribosomes from seven widely divergent bacteria (Streptomyces, Acetobacter, Pseudomonas, Azotobacter, Escherichia, Streptococcus and Bacillus) were determined by analytical ultracentrifugation. The bacteria were selected to cover nearly the entire range of molar guanine + cytosine content of DNA. Correction for pressure and dilution was always negligible; correction for temperature was eliminated by working directly at 20·0°. The correction for concentration was the most important one. Further reduction to standard conditions (from dilute buffer to water) resulted in a change of about 3%. The corrected sedimentation coefficients, expressed as (s 20, w)0, were nearly the same for all these bacteria, being in the ranges 29·5±2, 37·5±2·8, 56·3±1·9, 76·7±2·5, 110·5±1·6 × 10−13 sec. It thus seems unlikely that these coefficients will be useful as an aid in bacterial taxonomy. Disruption of samples of the same bacterial suspension by ultrasonic treatment or with the French pressure cell frequently resulted in quantitative, and sometimes qualitative, differences in the yield of ribosomes.

SUMMARY: Synthesis of ornithine carbamoyltransferase by yeast grown in a medium containing a suboptimal concentration of biotin was less than in biotinoptimal yeast and was diminished still further when l-aspartate was included in the biotin-deficient medium, although the presence of this amino acid is known to cause restoration of nucleic acid and total protein synthesis. Addition of l-ornithine to biotin-deficient medium increased synthesis of the enzyme to a value approximately half of the maximum recorded in biotin-optimal yeast, but dl-citrulline, l-glutamate, l-proline, oleate, or cytosine and uracil and their nucleosides and nucleotides had little or no stimulatory effect on synthesis of the enzyme. l-Arginine had little effect on enzyme synthesis by biotin-optimal yeast but caused a marked decrease in synthesis of the enzyme by yeast grown in biotindeficient medium containing l-aspartate. With yeast grown in unsupplemented biotin-deficient medium, but not in this medium supplemented with aspartate + ornithine, norbiotin (10−8 m) restored synthesis of the enzyme to a level greater than the maximum recorded in biotin-optimal yeast. Homobiotin (10−8 m) had a similar though less marked effect.

SUMMARY: Isoleucine increased the quantity of α-acetolactic acid-forming enzyme which takes part in the synthesis of valine and isoleucine in Pseudomonas aeruginosa. Threonine and α-ketobutyric acid, the precursors of isoleucine, had a similar effect. In P. aeruginosa during the initial stage of growth after inoculation, a temporary substantial increase of α-acetolactic acid-forming enzyme can be observed. This increase was not so great when valine was present, and was enhanced by isoleucine, which was effective during the whole period of growth. The repressive effect of valine can be counteracted with isoleucine and the end product inductive effect of isoleucine can be inhibited by valine. In extracts of disrupted organisms the activity of the α,β-dihydroxy acid dehydrase changes parallel with the concentration of the α-acetolactic acid-forming enzyme.

In the case of Escherichia coli the repressive effect of valine on the α-acetolactic acid-forming enzyme can be counteracted with isoleucine.

SUMMARY: In order to study the distribution of the murine toxin in Pasteurellapestis, whole organisms were converted to spheroplasts by treatment with penicillin or glycine in a sucrose medium. The spheroplasts were broken by osmotic lysis and homogenization. After centrifugation and washing, the membrane residues contained about 10% of the total activity of the spheroplast; the remainder of the toxic activity resided within the cytoplasm. Ribosomes were of low toxic activity. Magnesium ions selectively inhibited the destruction of these membranes by sonic oscillation; their treatment with trypsin resulted in the release of large amounts of non-toxic protein and peptides. Varying the temperature during spheroplast formation altered both the distribution of toxin between the anatomical components as well as the amount of toxin synthesized. Preliminary tests indicated that toxin obtained from the membrane and that found within the cytoplasm were identical.

SUMMARY: The carotenoids of two Cryptophytes, one heterokont and five Rhodophytes have been examined. The main pigments present are, in Cryptomonas sp., α-carotene, and diatoxanthin; in Hemiselmis virescens, α-carotene, and diatoxanthin; in Vischeria sp., β-carotene and three unidentified xanthophylls; in Antithamnion plumula and Nemalion multifidum, β-carotene, lutein and neoxanthin; in Erythrotrichia carnea, Rhodosorus marinus and Polysiphonia fastigiata, β-carotene, zeaxanthin and lutein.

SUMMARY: Type cultures or proposed neotype cultures of 20 species in the genus Bacillus are listed, together with their histories and their accession numbers in the American Type Culture Collection, the National Collection of Industrial Bacteria and the National Collection of Type Cultures.

SUMMARY: Susceptible bacteria are clumped in the presence of purified chemically-separated T-even tail fibres. The clumping is partially host-specific, serologically specific, and dependent upon the ionic environment. The clumping principle is adsorbed by bacterial suspensions with coincident disappearance of tail fibres. Clumping is believed to be caused mainly by phage tail fibres and the evidence suggests that the mechanism is by the formation of bridges between bacteria. It is inferred that the tail fibre must have at least two adsorbing sites.

SUMMARY: An agent which induced acidity and cytopathic effects in HEp-2 tissue cultures was investigated. The agent grew well in certain other tissue culture systems. Typical mycoplasma colonies were isolated from the contaminated HEp-2 cultures and on re-inoculation into HEp-2 cultures produced effects indistinguishable from the original effects. There was no appreciable growth in tissue culture medium alone. The mycoplasma had biological properties similar to those of known mycoplasmas, including Mycoplasma hominis type 1 (the common tissue culture contaminant), but was serologically distinct from these. Fluorescent antibody and Giemsa-staining techniques showed extracellular forms. Other mycoplasmas were shown to grow in tissue culture; M. gallisepticum induced similar effects to the cytopathic agent but was distinct in serological and biological properties. The agent partially inhibited the growth of measles virus.

SUMMARY: A survey has been made of the immunological relationships between glutamate dehydrogenase (GDH) and the related proteins of the amination deficient (am) mutants of Neurospora crassa. Serum against GDH was prepared in rabbits which had been injected with crude extracts of wild type N. crassa. The effect of this serum on the activity of normal GDH and the activity of activated mutant proteins was studied. The techniques of double diffusion in agar gel and of immunoelectrophoresis were used to study the relationships between the wild-type GDH and mutant forms of the protein. The identification of the relevant precipitation line on these gel plates was confirmed by the use of a specific stain for the enzyme antibody complex. The relationship between the antigenic and enzymic sites in the wild-type protein is discussed.

SUMMARY: A newly isolated strain (c) of Thiobacillus thioparus is described. The organism oxidizes thiosulphate, sulphide, tetrathionate or trithionate to sulphate; carbon dioxide fixation is coupled to the oxidation of each of these compounds. Concentrations of arsenate, 2,4-dinitrophenol, and other inhibitors of oxidative phosphorylation, inhibit carbon dioxide fixation without appreciably affecting oxygen uptake. Carbon dioxide fixation coupled to sulphide oxidation is more sensitive to arsenate and 2,4-dinitrophenol inhibition than that coupled to thiosulphate oxidation. This result is consistent with the suggestion that thiosulphate oxidation is linked to a substrate phosphorylation which is relatively insensitive to inhibition by 2,4-dinitrophenol and arsenate.

SUMMARY: Homogenates of brains from mice clinically affected with scrapie have been fractionated by differential centrifugation and equilibration in sucrose density gradients. Most of the infectivity was found in the heavy particulate fraction containing mitochondria and possibly lysosomes.

SUMMARY: The rate of decrease in optical density (increase in size of organisms) was determined in washed suspensions of a strain of Pseudomonas aeruginosa after they were added to potassium, sodium, or potassium + sodium phosphate buffers. The rate was increased by the addition of pyruvate or acetate. The maximal effect of pyruvate occurred in potassium + sodium buffer; of acetate in potassium buffer. Rate changes were also dependent on pH value and osmotic pressure.

SUMMARY: Purified teichoic acids and extracts with group-specific activity have been examined with specific antisera for a number of lactobacilli. The wall teichoic acids from groups D and E lactobacilli have been identified as the group-specific substances, whereas in group A the intracellular teichoic acid showed group-specificity. It is possible that group-specificity is associated with intracellular teichoic acid in group F.

SUMMARY: Cultures of form 2 mycobacteria, which had been recently isolated from form 1 of strains of Mycobacterium tuberculosis and atypical mycobacteria, were cultivated on nutrient agar in screw-capped bottles and kept unopened for 6 weeks at room temperature. Gram-positive granules developed in organisms which had penetrated into the medium. When these organisms were incubated in digest broth at 37° with intermittent aeration, the granules were liberated into the medium and gradually increased in size to that of a small coccus. After a resting period of about 2 weeks, the ‘cocci’ started to multiply independently, forming diplococci and tetrads. At this stage the cocci yielded colonies on subculture on nutrient agar. The cocci were identified as members of the genus Mycococcus, family Mycobacteriaceae, order Mycobacteriales (Krassilnikov, 1959). Mycococci were not obtained in broth cultures which were either not aerated or were aerated frequently or continuously. Prolonged subcultivation of the parent form 2 strains on nutrient agar prevented the development of mycococci in broth. Evidence, such as the failure to isolate mycococci from uninoculated but aerated media, is submitted that the mycococci were not contaminants. Previous work on isolation of similar cocci from different members of the order Actinomycetales, including human and bovine strains of M. tuberculosis is reviewed.