- Volume 48, Issue 1, 1967

SUMMARY: Corynebacterium xerosis Strain NCIB 9956 (minimum temperature for growth about 20°) formed clumps in cultures or suspensions of bacteria from these cultures, when grown at 30° and rapidly cooled to 15° with fast stirring. Electron microscopy showed whole organisms to be connected by an adhesive material. Electron micrographs of thin sections showed that clumps appeared to be formed by single layers of bacteria collecting round gas bubbles. The extent of clumping was greatest around pH 3, and increased as the temperature was decreased from 30° to 15°. Substitution of nitrogen or oxygen for air as gas phase had little effect on the clumping. The clumping ability increased with the age of the culture from the mid-exponential to the late-exponential phase of growth, but thereafter declined. Salts were necessary for clump formation. The relative effects of different monovalent cations and anions depended on the positions of the ions in the Hofmeister series. Incubation of bacteria in buffered solutions of proteolytic enzymes decreased their clumping ability. The extent of clumping also decreased when bacteria were incubated in buffered solutions of guanidine HCl (5 M), urea (8 M) or in a solution of uranyl nitrate (10 mM) and NaCl (0.1 M). Isolated walls of the organism formed clumps when suspensions in phosphate buffer (pH 7.0) were incubated at temperatures between 35° and 5° with fast stirring. Pretreatment of walls with trypsin decreased clumping ability. The ability to form clumps when cultures were cooled to 5° with fast stirring was demonstrated with several but not all of the strains of C. xerosis tested.

SUMMARY: Vegetative organisms of Azotobacter chroococcum, as seen by electron microscopy of ultra-thin sections, had a single, very thin wall, surrounded by a capsule which appears to correspond structurally to an outer wall. The smaller gonidial forms had double walls and no capsule. Cysts had a spore-like multiple wall, and give evidence of being produced within the cell.

SUMMARY: Electron microscopy of sections of Azotobacter chroococcum show that gonidia c. 0.05 μ are produced by or near the cell envelopes, increasing in size to c. 1 μ and filling the lumen of the cell before release, which occurs by rupture of the envelopes.

SUMMARY: The nodules of yellow lupin plants (Lupinus luteus L.) increased logarithmically in wet weight, leghaemoglobin and rhizobial numbers. Bacteroids were isolated from such nodules and the changes in concentration of protein, RNA and DNA per organism were followed as a function of nodule age. Six weeks after emergence, DNA and RNA per organism had fallen to 40% and 13%, respectively, of the values found in the bacteria from 1-week-old nodules. No further changes in RNA and DNA were found after this time. The decreases are discussed with reference to previous reports of loss of nuclear material during bacteroid formation.

SUMMARY: The rate of utilization of maltose in shaken cultures of a strain of Corynebacterium diphtheriae Park Williams 8 was much higher than that of the N source. Considerable gain in toxin yields was achieved when maltose or some intermediates of its metabolism (glucose, glycerophosphate, lactate, acetate) were added to the cultures between 20 and 32 hr of incubation. When, however, the initial concentration of these carbon sources in the medium was increased above the usual value (25 mg./ml.) a decrease in toxin formation resulted. The carbon intermediates were active at concentrations up to 15 times lower than that of maltose. Their action on the toxin titre was immediate, as contrasted to the lag of 3-4 hr which followed the addition of maltose.

SUMMARY: By the use of Freund's complete adjuvant, high-titre agglutinating antisera were prepared to nine trypanosomatids: Crithidia fasciculata (Anopheles strain), C. fasciculata (Culex strain, Wallace isolate), C. fasciculata (Culex strain, Nöller isolate), C. luciliae, Crithidia sp. from Euryophthalmus davisi, Leptomonas sp. from Dysdercus suturellus, L. mirabilis, and Blastocrithidia leptocoidis. The three C. fasciculata strains (Culex, Wallace isolate: Culex, Nöller isolate: Anopheles strain) and C. oncopelti are immunologically similar according to agglutination tests. Crithidia sp. from Euryophthalmus and C. luciliae are distinct from each other and from C. oncopelti. The two Leptomonas species are distinct from each other and are not closely related immunologically to Crithidia species. The trypanosomatids tested here are not separable into groups according to original host (hemiptera or diptera).

SUMMARY: Mycoplasma laidlawii and M. gallisepticum were found to incorporate [14C]acetate from the growth medium mainly into their polar lipids, whereas M. hominis and M. orale incorporated the acetate mainly into their neutral lipids. M. mycoides var. mycoides, Mycoplasma sp. strain 14 and M. fermen-tans did not incorporate acetate, although they were found to possess acetokinase activity. Most of the radioactivity of incorporated acetate was found in the fatty acid fraction of M. laidlawii lipids. Palmitic and stearic acids almost completely inhibited acetate incorporation by this organism, whereas oleic acid did not, indicating that the major part of the acetate incorporated by M. laidlawii was used for the synthesis of saturated fatty acids. Washed M. laidlawii required glucose, coenzyme A (CoA) and Mg2+ for acetate uptake. The uptake process was temperature-dependent and pH-dependent and was inhibited by several metabolic inhibitors, in particular iodoacetate. Pyruvate considerably enhanced acetate incorporation into M. laidlawii lipids without raising the low degree of radioactivity in the cell fraction soluble in cold trichloroacetic acid. Pyruvate did not replace glucose as an energy source for acetate uptake. Propionate and butyrate markedly decreased the acetate uptake, probably by inhibition of the acetokinase activity of the organisms.

SUMMARY: The substrate of basal respiration of conidia of Fusarium culmorum (W. G. Smith) Sacc. was found to be a mixture of triglycerides. The rate of utilization of this substrate increased when the conidia germinated. One of the main products of glucose metabolism in the germinating conidium was glucosamine which was a major constituent of the hyphal and conidial walls. The conidia fixed atmospheric carbon dioxide primarily into one compound, probably glutamine. Experiments on the conditions necessary for the swelling of the conidia indicated that metabolic pathways are involved, possibly terminating in the formation of glucosamine as the compound which initiates swelling. The use of tritiated water eliminated a theory of selective permeability as the mechanism for swelling; a theory based on a change in the elasticity of the conidial wall is now proposed.

SUMMARY: A new species and genus of the Actinomycetales is described, for which the name Intrasporangium calvum is proposed. The organism is a typical actinomycete, producing branching mycelium 0.4-1.2 μ in diam. which has a definite tendency to fragment. It is characteristic for the organism to produce sporangia intercalary in the mycelial hyphae. The sporangiospores are non-motile. This new genus is proposed to be a member of the family Actinoplanaceae.

SUMMARY: The requirement of a mutant strain of Escherichia coli for lysine + methionine was due to its inability to make lipoic acid. Aerobic growth of the mutant in minimal medium + lipoic acid was equal to that of the wild-type organism. The factor was replaceable by acetate + succinate. When grown without lipoic acid, suspensions of this organism did not oxidize pyruvate but did so upon addition of the factor; they also accumulated pyruvate from glucose. Extracts from deficient organisms did not oxidize α-ketoglutarate with 3-acetyl-NAD as acceptor. The growth requirements were only exhibited aerobically when provision of acetate + succinate required the operation of the lipoic-dependent pyruvate and α-ketoglutarate oxidase systems, respectively. Anaerobically, these metabolites were formed by lipoic-independent mechanisms, such as fumarate reductase which is repressed by oxygen.

SUMMARY: Preliminary agglutination and precipitin tests to which 60 newly isolated strains of Pseudomonas aeruginosa were submitted confirmed the existence of at least five serological groups. Ouchterlony precipitin tests and immuno-electrophoresis experiments, made with the concentrated trichloroacetic acid extracts of eight strains representative of these groups, revealed the antigenic heterogeneity of this species while the presence of at least 12 antigens was demonstrated. One of these was common to seven of the eight strains. Each of five strains, representative of five different serological groups, possessed at least one antigen peculiar to itself. The remaining ones appeared to be distributed at random among the strains. At least three different antigens migrated towards the positive electrode, of which two appeared to be electrophoretically inhomogeneous.

SUMMARY: The original strain of Vibrio 01 (Happold&Key, 1932) appears to have been lost. The Bacterium ncib 8250, which is frequently referred to as ‘Vibrio 01’, has different properties from those of the original isolate and is a Gramnegative non-motile oxidase-negative coccobacillus.

SUMMARY: Morphological, physiological, growth and chemosusceptibility characters were determined for 80 ‘atypical’ acid-fast and 3 non acid-fast strains isolated from tuberculous, or presumed tuberculous, patients, and for 24 control strains belonging to various mycobacterial species. Overall similarity analysis was used for establishing the relationships upon the basis of 60 characters codified by 153 features.

The overall analysis differentiated five clusters having mean matching indices above 80% (80 phenon = 80P), namely: 80P-I (human and bovine mycobacteria); 80P-II (‘atypical’ mycobacteria belonging to the Ist, IInd and IIIrd Runyon groups); 80P-III (mycobacteria related to Mycobacterium fortuitum); 80P-IV (scotochromogenic mycobacteria with greater metabolic abilities); 80P-V (M. smegmatis). Nine strains (among which were three non acid-fast bacilli) were not included in these clusters.

The ‘atypical’ mycobacteria cluster (80P-II) was formed by three clearly delimited subgroups, which broadly corresponded to Runyon's classification.

A more detailed analysis of certain groups, and the determination of the characters of some ‘hypothetical average organisms’, allowed the further differentiation of some subgroups and aberrant strains.

The need to standardize the coding methods is stressed. Because of the value of overall similarity in such a variable genus, an international system to classify and identify strains upon a phenetic basis is suggested.

SUMMARY: Alcohols, amino acids, organic acids and sugars were tested as carbon sources for the growth of Pyrobotrys (Chlamydobotrys) stellata in the light and dark. Growth was only recorded with acetate in the light. A carbon balance sheet of 14C-acetate assimilation showed a greater incorporation of 14C into polysaccharide and less released as 14CO2 in the light, compared with the dark. The primary products of 14C-acetate assimilation into the soluble fraction of the organisms were identified; after 10 sec. 40% of the total 14C present in this fraction was in succinic acid, 15% in citric acid and 16% in malic acid. The percentage of total 14C in this fraction present in succinic and malic acids decreased consistently with time, while that in citric acid initially increased before decreasing. After 10 sec. the specific activity of succinic acid was more than twice that of citric acid. 4 x 10−3 M-monofluoroacetate (MFA) effectively inhibited the incorporation of 14C-acetate into tricarboxylic acid cycle intermediates and related compounds, and markedly inhibited 14CO2 evolution. 10−6 M-N 1-(3-4, dichlorophenyl)-N,N-dimethyl urea (DCMU) did not significantly inhibit 14C-metabolism. The key enzymes of the glyoxylate cycle, isocitrate lyase (E. C. 4.1.3.1) and malate synthetase (E. C. 4.1.3.2) were found to be present in P. stellata, and did not disappear in the absence of acetate, but even so growth was not recorded on acetate in the dark.

SUMMARY: Pseudomonas aeruginosa 8602 was grown in continuous culture in minimal salts medium with 10 mM-succinate as carbon source. Changes in bacterial concentration and amidase activity were measured when the carbon source in the ingoing medium was changed to 10 mM-succinate plus 10 mM-acetamide. At low dilution rates (D = 0.2 hr−1) amidase synthesis occurred rapidly with little or no lag. At higher dilution rates the lag increased until at the highest dilution rate tested (D = 0.76 hr−1) almost no amidase had been synthesized 4 hr after the change of medium. It was concluded that at the highest dilution rates amidase synthesis was subject to catabolite repression by high intracellular concentrations of succinate and its metabolites. Severe repression of amidase synthesis was accompanied by incomplete utilization of acetamide for growth.

Periodic oscillations were observed in amidase activity and in bacterial concentration both during the transition period after the change of medium and when the culture had reached the new steady state. These oscillations occurred at all dilution rates and oscillations in amidase activity were also found when the non-substrate inducer N-acetylacetamide was supplied with 20 mm-succinate.

SUMMARY: The electrokinetic behaviour of intact conidia and cell walls of Neurospora crassa was studied using a micro-electrophoresis technique. By chemical and enzyme treatments it has been established that amino, carboxyl and phosphate groups are integral components of the spore surface; acid phosphate groups, however, were not found on the surface of washed cell walls. The fungicide dodine acetate reduced the negative charge on conidia to zero and, with increasing concentration, gave a positive charge to the spores: at lower fungicide concentrations the negative charge on the surface of cell walls and stabilized protoplasts was also neutralized. These results are consistent with an ionic reaction between the dodine cation and the carboxyl and phosphate groups of the cell. There was no evidence that the toxic reaction between dodine acetate and N. crassa conidia is located on the spore surface—the spores were completely killed before there was a perceptible reduction in electrophoretic mobility.