- Volume 38, Issue 2, 1965

SUMMARY: A small-scale apparatus for the continuous culture of anaerobic bacteria is described.

SUMMARY: Strains of Streptococcus bovis, Selenomonas ruminantium, and an anaerobic lipolytic bacterium (5s) have been grown under carbohydrate-limiting conditions in continuous culture for long periods. With S. ruminantium and bacterium 5s the fermentation products varied with growth rate. Yield of organism in continuous culture of all three bacteria showed a maximum at a particular growth rate. The yield of S. ruminantium was much higher in continuous culture at optimum growth rate than in batch culture, and was also higher than can be explained on present concepts of the energy from fermentation available for growth. The various results are discussed in the light of results obtained with other bacteria and the conditions obtaining in the rumen.

SUMMARY: Erythrocytes from various species of animals were tanned by exposure to 1/20,000 tannic acid for 10 min. at 37°, and were used in various haem-agglutination systems together with untreated red cells as control. The titre of fresh human anti-AB serum was decreased from 4-to 64-fold when tested with tanned homologous red cells, while no decrease of titre was observed in commercially prepared sera of the same group under identical experimental conditions. The titre of anti-sheep red cell serum was not appreciably affected when tested with tanned sheep red cells, but there was a 2-to 4-fold increase in the agglutinin titres of myxoviruses (influenza, mumps) tested with tanned chick or sheep red cells. The haem-agglutinin titres of West Nile and Sindbis viruses were not changed when tanned goose red cells were used instead of untreated red cells in haem-agglutination tests. Human, guinea pig and fowl red cells did not become agglutinable by West Nile and Sindbis viruses after treatment with tannic acid. West Nile and Sindbis viruses agglutinated sheep red cells to low titres. These titres were twice as high when tanned red cells were used instead of untreated cells. There was a sharp drop in the titres of anti-human cell sera when tested with tanned human group O red cells. It is suggested that tannic acid may act on certain species of red cell to increase or decrease their agglutinability in the presence of immune serum.

SUMMARY: For three streptomycin-dependent (S-dependent) strains of Escherichia coli, the streptomycin concentration necessary for optimal growth during incubation for 24 hr in a nutrient broth medium was about 10 μm./ml. Less than 5 μg./ml. was sufficient for fairly heavy growth and the minimal streptomycin concentration permitting appreciable growth was 0·40/μg./ml. Division of S-dependent bacteria was inhibited at streptomycin concentrations greater than 20 μg./ml. and small inocula gave no visible growth in 24 hr at more than 30 μg. streptomycin/ml.

Following addition of any of several salts to the growth medium at 0·05m growth occurred over a wide range of streptomycin concentrations and the optimum was increased from twofold to as much as 1000-fold. Maximal concentration of streptomycin in which growth of S-dependent Escherichia coli was possible increased to as high as 20,000 μg. streptomycin/ml. in some instances, and the minimal concentration which supported growth was increased in the presence of several of the salts. Salts also increased the degree of resistance of a streptomycin-resistant E. coli mutant from 20 to as much as 10,000μg. streptomycin/ml. In 0·10m phosphate-buffered nutrient broth, maximal and optimal concentrations of streptomycin increased with increasing acidity; at pH 5·8 heavy growth of an S-dependent strain of E. coli occurred at 200,000 μg. streptomycin/ml.

SUMMARY: Two biochemical variants were obtained from a strain of Streptococcus pyogenes, type 19. One variant, known as ‘starch-positive’, always produced amylomaltase, readily forming starch from maltose. The other variant, known as ‘starch-negative’, did not usually form starch from maltose in the same cultural conditions. The starch-positive variant had low mouse virulence and the starch-negative variant had high mouse virulence. The starch positive variant was avirulent for the rat, but the starch-negative variant had some rat virulence. Both variants had plenty of M antigen in precipitin tests and showed good anti-phagocytic power both in bactericidal tests with human blood and in surface phagocytosis tests with isolated human leukocytes. The mouse virulence of the starch-positive variant was enhanced by casein polypeptide and by human plasma. Starch-positive and starch-negative variants obtained from a type 12 strain also had the same properties.

SUMMARY: Study of the kinetics of the effect of KCl and NaCl on the genetic transformation process has shown that an activation of a 3 min.-old DNA-bacterial complex by 0·2m-salt is responsible for a several-fold increase in the frequency of transformation. It is assumed that this is due to activation of a temperature-dependent metabolic process which is connected with the penetration of DNA into the competent cells. Studies of the kinetics of DNA penetration, by the addition of deoxyribonuclease as a function of time, in the presence and absence of the activating salts, indicate that competence is also a state of increased permeability to macromolecules. The activating effect of both sodium and potassium chlorides bears some relation to the stage of competence achieved and to the dilution or non-dilution of the receptor culture.

SUMMARY: The glycogen content of peptone grown cultures of the ciliate Tetrahymena pyriformis gl, increased from 6% cellular protein during the exponential growth phase to 30 % or more in the stationary phase of growth. The oxygen content in the medium began to decrease at a population of 7500 organisms/ml. in gently shaken cultures and at 80,000 organisms/ ml. in well aerated cultures. In either case, depletion of oxygen in the medium was soon followed by cessation of multiplication. The stationary phase was rapidly induced by transfer of log phase organisms to conditions of restricted aeration. Within 3 hr after such a transfer, the rate of glyconeogenesis approximately doubled, both in cultures and in washed suspensions of organisms incubated with 0·1 % sodium acetate.

SUMMARY: Alter ultraviolet irradiation, the growth of Escherichia coli (non-lysogenic and lysogenic for phage λ) resulted in diminution of the 8S component of water extracts of the bacteria and the loss of its characteristic spike. In the induced lysogenic bacteria, 8S material was synthesized in the second half of the latent period and the characteristic shape of the boundary was regained. The 8S material was free DNA of relatively high molecular weight and these changes were correlated with alterations in the rate of DNA synthesis in the irradiated bacteria. The synthesis of ribosomal material was found to continue during the development of phage λ. After log phase bacteria had stood for a short time in saline, extracts prepared in tris buffer+0·01 m-magnesium acetate showed that an 85S component developed. The latter was replaced by slower material (73S) when the bacteria (non-lysogenic and lysogenic, irradiated or unirradiated) resumed logarithmic growth in broth. This conversion may reflect a configurational change in the 73 S component in environments which do not support growth.

SUMMARY: The base composition of DNA preparations from 12 strains of Streptomyces and 1 strain of Nocardia were determined from their denaturation temperature (T m) and buoyant density.

The % GC (guanine+cytosine) contents ranged from 74·4 to 78·5 (from T m) and from 69·4 to 73·4 (from buoyant density). The correlation between the two sets of data and the found differences are discussed. The range of pH values which did not affect T m and the degree of hyperchromic effect have been related to the ionic strength of the solvent. With 0·01 M-phosphate as solvent the pH indifference range was narrower and the hyperchromic effect smaller than with 0·2M-Na+ solvent.

Though the difference between the maximum and minimum % GC in Streptomyces is sufficient to distinguish the respective strains, within the extreme values there is a continuous progression of base composition which does not permit taxonomic divisions to be made on the basis of overall % GC alone.

SUMMARY: Several antibiotics were tested against a range of actinomycetes, bacteria and fungi representing types found in soil. From these tests four antibiotics, nystatin (50 μg./ml.), actidione (50 μg./ml.), polymyxin B sulphate (5·0 μg./ml.) and sodium penicillin (1·0 μg./ml.), were selected for incorporation into a starch + casein medium to achieve selective growth of actinomycetes on soil dilution plates. This mixture of antibiotics was tested with a number of soils and its efficiency compared with several other methods for selective development of actinomycete colonies. The most suitable mixture for the enumeration of soil actinomycete colonies was starch + casein medium with the two antifungal antibiotics (nystatin, actidione); for isolation of actinomycete colonies the same medium with all four antibiotics was the most satisfactory.

SUMMARY: An electronic computer was used to integrate differential equations for bacterial growth, and thus to determine simultaneously growth-rate constants, saturation (‘Michaelis’) constants, and initial numbers of bacteria. In one case numerical methods were necessary to effect the integration and the work would have been prohibitively great if a computer had not been used. By this means curves have been fitted to experimental data on the course of nitrification in water from the Thames Estuary.

Kinetic constants for Nitrosomonas and Nitrobacter at various temperatures were obtained, and the rate of death of these bacteria in the absence of their substrates was estimated.

SUMMARY: Enterococci mainly from laboratory collections were separated by established and new or modified tests into two distinct species, Streptococcus faecalis and S. faecium. Of the established tests only reducing activity and potassium tellurite tolerance completely differentiated the organisms. Of the additional tests the most useful were fermentation of glycerol in a soft agar medium containing fumarate, H2O2 formation from polyhydroxy alcohols and the ability to ferment them, H2O2 formation on a basal medium containing no added specific energy source, citrate fermentation and dissimilation of malate in the presence of glucose. Catalase activity and the ability to use malate as an energy source were also useful tests but did not completely differentiate the organisms.

SUMMARY: Spicules morphologically similar to those present on the spores of Pithomyces chartarum invest the spores of several other Pithomyces species. Depsipeptides are quantitatively removed from dried mycelial felts by brief chloroform washing, and their amount is proportional to the number of spores present. Three pure spore-coat depsipeptides have no demonstrable antibiotic activity.