- Volume 8, Issue 2, 1953

SUMMARY: The Schmidt & Thannhauser (1945) procedure was applied to the nucleic acid fractions of Streptococcus faecalis. A part of the deoxypentose nucleic acid was differentiated as being insoluble in n-NaOH at 37°, and appeared to be firmly bound to polysaccharide material. Base analyses of the nucleic acid fractions are reported, and qualitative determinations of the amino-acid and sugar composition of the residue described.

SUMMARY: Bacteria possessing active amino-acid decarboxylases, isolated from horse-stomach and sheep-rumen contents, were classified within the genus Lactobacillus. One strain, studied in detail, was a homolactic fermenter, the lactic acid formed being optically inactive; lactose was not fermented. Of twenty-six named strains belonging to eight species of the genus, only two possessed amino-acid decarboxylases, namely, one strain of L. pentoaceticus and one strain of L. bifidus.

SUMMARY: The histidine decarboxylase produced by a species of Lactobacillus (strain 30a isolated from horse-stomach contents; Rodwell, 1953a) has been examined in detail. Attempts to resolve a cell-free enzyme preparation into an inactive apoenzyme and a coenzyme were unsuccessful. Cells grown in a medium deficient in pyridoxin had greatly diminished lysine and ornithine decarboxylase activity, whereas their histidine decarboxylase activity was not at all diminished.

SUMMARY: The strain of Lactobacillus used (strain 30a) possessed decarboxylases specific for l-histidine, l-lysine and l-ornithine. The rate of decarboxylation increased after a lag period to a maximum value which was dependent on the concentration of pyridoxal. A number of factors was found to affect the rate of activation of the apoenzymes, or, it is thought, probably the rate of pyridoxal phosphate synthesis. Among these factors were: the presence in the test system of the specific substrate for the decarboxylase, the concentration of pyridoxal, and the pH value of the test system. Cells grown in medium deficient in both pyridoxin and folic acid had greatly decreased activation rates for ornithine apodecarboxylase, and pyridoxal phosphate synthesis was also decreased. The addition of folic acid to the system did not affect the rate of activation with folic acid-deficient cells. The addition of thymine to the test system increased the activation rate for folic acid-rich cells, but had no effect with folic acid-deficient cells; other purines were ineffective. It is concluded that some product of thymine metabolism which folic acid-deficient cells are unable to make is concerned with the biological phosphorylation of pyridoxal by this organism.

SUMMARY: Labyrinthula vitellina var. pacifica requires a steroid as growth factor. Cholesterol, Δ4-cholestenone, fucosterol, and β-sitosterol are active. When cholesterol is modified by (1) the C3‡ hydroxyl group becoming trans to the C10 methyl group, (2) esterification of the C3 hydroxyl group, or (3) saturation of the C5, 6 double bond, the resulting compound is inactive. Modification of the side chain of cholesterol or cholestenone by the addition of a C24 ethyl or vinyl group does not destroy activity but unsaturation at C22, 23 does, as do the more marked changes found in diosgenin, deoxycorticosterone acetate, and methyltestosterone. Bile salts are inactive. The specificity of the requirement indicates that active steroids function as essential metabolites rather than solely as protective agents. Active steroids may be obtained by this micro-organism in nature from host plants or from diatoms and bacteria associated with the hosts.

SUMMARY: Serum could be replaced in media for growing the L-phase of Proteus vulgaris by a phospholipid fraction from egg yolk and for growing the L-phase of Streptobacillus moniliformis by the addition of this fraction + bovine albumin. Organisms of the pleuropneumonia group grew in media in which serum was replaced by these materials; only with the further addition of cholesterol. The L-phase organisms thus differ in nutrient requirements from the pleuropneumonia group. They also differ in their requirements from the parent bacteria. Differences were noted in colonial appearances between the L-phase organisms studied and the organisms of the pleuropneumonia group.

SUMMARY: Isolated colonies of anaerobic bacteria can be obtained in a layer of agar enclosed between a watch-glass and a glass plate. They can be examined and removed without difficulty.

SUMMARY: At high aeration rates in submerged culture, lard oil (mainly glycerides of oleic and stearic acids) may be utilized by Penicillium chrysogenum as a source of carbon in preference to carbohydrate. At relatively low aeration rates, carbohydrate serves as the principal carbon source.

Enzymes involved in the utilization of lard oil appear to be synthesized by the growing mycelium, this synthesis being favoured by conditions of high aeration.

SUMMARY: A Gram-negative motile bacterium isolated from soil can grow with naphthalene as sole carbon source and produces from it d-trans-1:2-dihydro-1:2-dihydroxynaphthalene and salicylic acid.

SUMMARY: When the guanine analogue, 5-amino-7-hydroxy-1-v-triazolo (d) pyrimidine (guanazolo), was sprayed on the leaves of tobacco or Nicotiana glutinosa plants it reduced the number of local lesions and delayed or inhibited systemic spread of lucerne mosaic virus. Guanazolo was more effective when applied before inoculation, but had some effect if applied up to about the second day after inoculation. The compound was more effective in solution in 0·1% sodium bicarbonate than in aqueous suspension. With mechanically inoculated plants guanazolo watered on the soil around the plants was less effective than when sprayed on the leaves.

Incubated with the virus in vitro the compound did not affect infectivity. In concentrations up to c. 0·005m guanazolo usually caused negligible plant damage, but at higher concentrations produced a slight yellowing and distortion in the younger leaves with general stunting if treatments were prolonged.

The virus-inhibitory activity of guanazolo was reversed by adenine, guanine and possibly by hypoxanthine, but not by xanthine, uric acid, theobromine, theophylline, caffeine, uracil or thymine.

The triazolo analogue of adenine severely damaged plants and had only slight virus inhibitory activity. The hypoxanthine analogue caused no plant damage. It was less effective than guanazolo in tobacco and N. glutinosa but more effective in reducing the number of local lesions produced in beans. Thiouracil, methyl-thiouracil and propylthiouracil were ineffective against lucerne mosaic virus. Thiouracil caused fairly severe plant damage.

Guanazolo had slight or negligible effects on spotted wilt virus in tomato, potato viruses X and Y in potato, and tobacco and pea mosaic virus in peas. Applied as a leaf spray at 0·01m concentration guanazolo delayed or prevented systemic movement of cucumber mosaic virus from mechanically inoculated cucumber leaves, but had no effect when watered on the soil. However, watering the compound on the soil gave some control when the virus was introduced by aphids.

SUMMARY: Microsporum canis Bodin, the causative agent of animal ringworm in children and adults, is able to digest human hair keratin in vitro. The process of degradation has been followed by microscopic observation and an analysis of the resulting amino-acids which accumulate in the medium after growth on human hair has been made by chromatographic techniques.

SUMMARY: A statistical method is described to test the compatibility between results of local-lesion counts and hypotheses relating changes in infectivity of plantvirus preparations to treatments applied to them. The method allows the varianceratio test to be applied: it involves establishing a relation between numbers of lesions and virus concentration for each experiment and a logarithmic transformation of lesion counts to make variance independent of the magnitude of the variate. Its use is illustrated with results obtained to see whether inactivation of viruses by ultraviolet radiation is a first order reaction.

SUMMARY: Chromatographic examination of an aqueous extract of jute showed the presence of inorganic phosphate, glucose-6-phosphate, fructose-1:6-diphosphate and calcium ion. A mixture of the last three in the amounts estimated to be present in the jute extract stimulated early and vigorous formation of perithecia of Chaetomium globosum in the same manner as does jute extract, although the amount of vegetative growth was appreciably less. No indication of the presence of a specific ‘fruiting factor’ was obtained.

When a strain of Bacterium coli derived from a single cell is grown under conditions approaching anaerobiosis, three different types of cell can be demonstrated: cells which divide to give the normal colonies; L-form; and an intermediate type which appears normal, divides once giving two daughter cells, one of which continues to divide normally while the other becomes an L-form.

An organism isolated from a top-fermentation beer was found to be a new heterofermentative species of Lactobacillus. It appears as very small rods of length 1·0–1μ5μ. and width 0·8–1·0μ. and forms chains. It ferments only glucose, maltose and sucrose and has been named L. parvus.

The total amount of growth of Aerobacter aerogenes and Bacterium coli in glucose ammonium salt media which provided substrates in excess was dependent on the initial pH value in aerated and unaerated cultures. Total crops in aerated cultures were always higher for any particular initial pH value, and for cultures inoculated at pH values less than 7·0 the pH fell to lower values in aerated than in unaerated media. Growth of a culture of A. aerogenes in its (unaerated) stationary phase resumed on aeration; when the pH value at inoculation was 5·0–6·0, the pH continued to fall; when the pH value at inoculation was 6·1–7·0, the pH rose slightly. Growth of similar cultures of Bact. coli lagged when aerated; pyruvate concentrations immediately increased and pH values fell when glucose was in excess but not when it was limiting for growth. The concentration of formic acid produced by fully grown cultures was sufficient to abolish growth in fresh media below pH 5·25 but not at pH 7·0. These observations are discussed in relation to views on the influence of aeration on growth.

Relationships between total growth and initial pH value of citrate media were established for aerated and unaerated cultures of A. aerogenes. Growth in unaerated media ceased at pH values slightly higher than those at inoculation, leaving some citrate unconsumed. Aeration then caused growth resumption accompanied by consumption of citrate and a further increase in alkalinity.

Purified tissue enzyme preparations, particularly bovine pancreatic deoxyribonuclease, have been shown to inhibit specifically pathogenic strains of Mycobacterium tuberculosis. Destruction of the enzymic activity did not influence this effect. Inhibition in Dubos's medium was markedly increased by Tween 80 but not by other surface active agents. Antibiotic potentiation by Tween 80 alone or combined with the tissue extracts was observed. The antimycobacterial activity of spermine was confirmed, but there was no evidence that it was present in our extracts and the inhibitory substance has not yet been identified.

Details are given of a new species of the genus Lactobacillus isolated from a sample of brewery yeast. The cells appear as short thick rods, mainly in pairs and small clumps. This organism, which ferments arabinose, xylose, glucose, fructose, mannose and sucrose, has the low optimum temperature of 22–23° and fails to grow above 30°. It has been named Lactobacillus frigidus.