- Volume 5, Issue 4, 1951

When Alternaria solani is grown on any one of a variety of defined culture media, an antibiotic metabolic product, alternaric acid, accumulates in the medium. The quantity of alternaric acid produced is directly related to the amount of mycelium formed; good yields of alternaric acid are obtained on any medium which supports good growth. Optimal media contain high concentrations (7·5% (w/v) or more) of sucrose, which is better than any other carbon source tested. Nitrogen may be supplied as nitrate or casein hydrolysate; ammonia as nitrogen source is equally good when supplied in conjunction with a suitable organic acid, 0·25% (w/v) acetic acid being particularly favourable.

The antibiotic is isolated from optimal media by extraction with chloroform after adjustment to pH 3·5; the solvent is then evaporated and the residue recrystallized from benzene. Yields of the order of 150 mg./l′ are obtained.

Alternaric acid is not antibacterial. Germination of spores of some fungi (e.g. Absidia glauca, Myrothecium verrucaria) is prevented by 1μg./ml. or less of alternaric acid. Germination of spores of other fungi (e.g. Botrytis allii) is unaffected by concentrations as high as 100 μg./ml., but extension of the germ-tubes is markedly retarded shortly after germination. This secondary retarding effect may be produced by very low concentrations; 0·1 μg./ml. produced an obvious effect with B. allii.

SUMMARY: Substances found to be essential for pyocyanine production by Psaulomonas aeruginosa were Mg, PO4, SO4 and NH4 ions, together with a carbon source, preferably glucose, glycerol or ethanol. Ca, Na, K, Fe ions were not essential, nor was asparagine. Pyocyanine was formed in nutrient broth prepared with distilled water; the addition of chalk improved pigment production. Reliable and good yields were regularly obtained on an ordinary broth medium containing glucose (0·2%) and chalk.

Recommended media for stimulating pyocyanine production were tested. Turfitt′s medium gave more reliable pyocyanine formation when the NH4NO3 was replaced by NH4Cl and chalk was added. Increasing the MgSO4. 7H2O content of this medium from 0·25% to 0·2% inhibited pyocyanine production.

Various amino-acids were tested. Glycine, l-tyrosine, dl-alanine, l-leucine, when added separately or in various combinations to a salt mixtureglucose, glycerol or ethanol permitted the production of pyocyanine. A mixture of glycine, l-leucine and dl-alartine (recommended by Burton, Campbell & Eagles, 1947) exerted a stimulating effect on pyocyanine production far superior to that obtained on any other medium tested.

The highest yield reached was 231 mg. pyocyanine/100 ml. of a medium consisting of: 0·4% dl-alanine; 0·8% l-leucine; 0·2% MgSO4. 7H2O; 0·05% K2HPO4; 0·001% FeSO4. 7H2O; 1% glycerol and chalk.

The heat-stability of the T antigen of strains of Streptococcus pyogenes grown in Pope &Smith (1932) broth (containing maltose and yeast) with added pancreatic extract varied considerably from strain to strain; with several strains 30 minutes' boiling was insufficient to eliminate all T agglutinability.

By heating suspensions of streptococci to 80 for 30 min. and then treating the heated suspensions with trypsin-containing pancreatic extract for a few hours, T antigen was obtained in solution and could be demonstrated by precipitin tests with appropriate type-specific sera.

SUMMARY: The growth-promoting action of β-alanine on Saccharomyces carls-bergensis and two strains of S. cerevisiae is stimulated or inhibited to different extents by the optical enantiomorphs of methionine, glutamic acid, asparagine and a-alanine. This behaviour can be considered as due, in each individual case, to one or more of three separate effects: (a) stimulatory, (b) inhibitory, and (c) antagonistic. In general, the l-forms of the amino-acids have a more pronounced action than the d-isomers. Racemic mixtures have intermediate effects. Similar but less striking results are observed when β-alanine is replaced by pantothenic acid. Atypical effects are obtained with d-alanine and d-glutamic acid.

SUMMARY: Phase-contrast microscopy enables germination to be studied in the spores of Bacillus cereus and B. subtilis a few minutes after the addition of adenosine; by this means adenosine can be identified in minute concentrations. Adenosine in high concentrations is, however, inhibitory to vegetative growth.

Adenosine appears to act as an indicator of conditions suitable for vegetative existence, and induces, almost instantaneously, profound physical changes in spores. The analogy with hatching of eel-worm and amoebic cysts, also susceptible to specific excitants, is stressed.

SUMMARY: When holotrich ciliates of hay-fed sheep’s rumen acted upon water-soluble carbohydrates under conditions comparable with those in the rumen save for the absence of appreciable bacterial competition, only glucose, fructose, sucrose, inulin, bacterial levan (from Bacillus megatherium) and to a lesser extent celloblose were utilized for rapid and extensive storage of iodophilic polysaccharide granules (cf. Oxford, 1951). No other soluble carbohydrate tried (including maltose) was so utilized. When polysaccharide storage did take place the product always gave a purple colour with iodine, and had the properties of a starch rather than glycogen in that it gave an insoluble iodine complex under the conditions of Pucher, Leaven-worth & Vickery (1948). Storage of starch by oligotrich ciliates was much slower than with holotrichs, and did not take place with cellobiose as substrate, Holotrich ciliates continued to replace themselves in the sheep's rumen even when large volumes of rumen contents were periodically withdrawn over a long period. The protozoan starch could be isolated in about 1% yield by application of the Pucher et al. (1948) method direct to the dry matter of strained rumen liquor taken from sheep which had grazed on starch-free Spring grass.

SUMMARY: The role of electrolytes in the adsorption of the citrate-sensitive staphylococcal typing-phages and the citrate-insensitive phage K on to their propagating strains was studied in broth+Na citrate and in distilled water+CaCl2, MgCl2, and NaCl. Some phages when in the free state were partially inactivated by 1% (w/v) Na citrate. In all except two phages, K and 51, citrate inhibited adsorption in broth; adsorption occurred in distilled water. Three phages, 7, 42B and 42E, had a specific requirement of 50 µg. CaCl2/ml. for adsorption. With the remainder, the requirements of CaCl2 varied from 5 to 400 µg./ml.; similar amounts of MgCl2 acted equally well.

With the citrate-sensitive phages adsorption in NaCl was variable and, where it occurred, recovery of viable phage from cells infected in NaCl was less than from cells infected in CaCl2. These phages appear to have a specific requirement of divalent cations for adsorption, suggesting that adsorption and penetration are enzymic in character.

The electrolyte requirements of the citrate-insensitive phage K were related geometrically to the valence of the cations used, 5 µg. CaCl2 or MgCl2/ml, or 25 µg. NaCl/ml. giving optimum adsorption.

SUMMARY: By a simple chromatographic technique with filter-paper disks the distribution of glutamic acid decarboxylase in the family Enterobacteriaceae was surveyed. The decarboxylase occurred irregularly among 230 strains belonging to this family. The test for glutamic acid decarboxylase may prove to be of value in the classification of organisms related to the genus Salmonella, in the classification of paracolon types and in the identification of sub-groups within the genera Escherichia and Aerobacter.

SUMMARY: The amount of coagulase formed in vitro by coagulase-positive staphylococci depends on: the age of the bacterial cells, coagulase being produced only during the latter part of the lag-phase of growth; the period of incubation of the bacterial cells under ideal conditions, the optimum period depending upon the age of the cells when incubation starts; the initial concent ration of bacteria. It also depends on the presence in the medium of a fermentable sugar and a factor found in brain-heart infusion and partially replaceable by peptone; the salt concentration in the medium; the initial pH value of the medium; the temperature of incubation: and upon substances present in rabbit serum and, to a lesser extent, horse serum, human serum and egg yolk, egg white and commercial nucleic acid not showing this effect. The activity of rabbit serum is destroyed by treatment with pepsin. Provided that the requisite conditions are met, cell-free coagulase which clots rabbit plasma within a few minutes, can be prepared in less than one hour.

SUMMARY: The serum-protein determination method of Robinson & Hogden (1940), using the biuret reaction, has been applied to the determination of small quantities of bacteria. This ‘direct protein' estimation involves about three-quarters of the total protein of the bacteria.

SUMMARY: Osmophilic yeasts are found in the film of molasses on the crystals of raw sugars and in intermediate sugar-refining products of a wide range of concentration. They are allied to yeasts found in similar situations such as concentrated fruit juices, etc., and can be made to spore more or less freely under dry conditions, usually with conjugation. They are unable to destroy sucrose in strongly buffered solutions; some are able to produce sufficient acid from traces of invert sugar present gradually to invert the sucrose. During this process multiplication takes place. Previous workers have shown that the majority of organisms of this group is highly acid resistant.

Organisms which grow in a wide range of concentration of dissolved solids (salts, sugar) show, at acid pH values, an adaptation to growth in higher concentrations accompanied by a diminished metabolic rate. This is lost after a period of 6· 8 weeks in dilute media, but can be revived in many cases by increasing the sugar concentration in not less than two steps. Temperature resistance is also increased in concentrated media.

SUMMARY: A liquid medium based on peptone, yeast extract and glucose is described, which is capable of supporting massive growth of Desulphovibrio desulphuricans ‘Hildenborough’ and certain other strains of sulphate-reducing bacteria. When peptone is used in large amounts yeast extract may be omitted, though yeast extract is stimulatory when the peptone supply is suboptimal. Glucose is better than lactate in this medium. Bicarbonate increases the growth rate. More than one factor is responsible for growth stimulation by peptone and yeast extract; the factors responsible for the stimulation shown by yeast extract in the presence of inadequate peptone are water-soluble and not removed by various extraction procedures. Cysteine promotes growth, and serine, ornithine and isoleucine act synergistically with it. These amino-acids do not account for the whole activity of peptone and yeast extract.

SUMMARY: Desulphovibrio desulphuricans, strain ‘Hildenborough’, was able to use sulphite, thiosulphate, tetrathionate, metabisulphite or dithionite in place of sulphate for growth. Resting cell suspensions reduced these ions using the theoretical amounts of hydrogen and forming the theoretical amount of sulphide, except in the case of dithionite, which probably decomposed spontaneously to sulphate and sulphur before being reduced.

The organism was unable to grow with or to reduce dithionate, perdisulphate, ‘formaldehydesulphoxylate’, sulphamate, benzenesulphonate, methanesulphonate, β-hydroxyethane-sulphonate, sodium ethylsulphate, dimethylsulphone or cystine. Elementary sulphur, if purified by re-distillation, was also not attacked. Five other strains of D. desulphuricans, four of them cultivated autotrophically, were also unable to grow with pure elementary sulphur.

Colloidal sulphur permitted slow growth, or slow hydrogen absorption when a resting cell suspension was used. This effect was not due to oxide impurities in the sulphur permitting growth, as an ultra-filtrate of colloidal sulphur had considerably less activity.

A study of the rates of H2 uptake suggested that sulphur, thiosulphate and tetrathionate were not intermediates in normal sulphate reduction, but that sulphite was.

SUMMARY: Normal mouse serum contains a haemagglutination inhibitor and a neutralizing factor for influenza virus. The inhibitor and the neutralizing factor are heat-labile, can be destroyed by a crude filtrate of Vibrio cholerœ and are much more active towards unadapted virus than towards mouse-adapted virus. The inhibitor enters into stable combination with the virus in the presence of Ca ions. It is adsorbed by a large amount of unadapted virus, even after the haemagglutinin of the latter has been destroyed by heating at 60° for 15 min. Three strains of freshly isolated influenza B virus tested were not significantly neutralized by normal mouse serum. By growing two strains of unadapted influenza A virus in eggs in the presence of normal mouse serum, two variants which are resistant to the neutralizing action of mouse serum were produced. It appears that this type of variation also occurs when an unadapted virus is passed in mice. The theoretical implication of this type of variation in response to a normal host component and its relationship to the mouse-pathogenicity of influenza virus are discussed.

SUMMARY: Haematin in concentrations of 1/1,000,000 1/2,000,000 inhibited the growth of a number of bacteria most of which were aerobic sporing bacilli. Deuterohaematin and mesohaematin were also inhibitory, but not haematohaematin, urohaematin and a number of iron-free porphyrin derivatives. In a few cases whole blood was inhibitory, but generally only trypsin-digested laked red cells. The mechanism of the antibacterial activity is not understood.

SUMMARY: Extracts of a strain of Aspergillus fumigatus stimulate fruiting of Chaetomium globosum, but the factor responsible is not identical with that present in jute extract. Hexose phosphates, although stimulating fruiting, do not account for the activity of the jute extract.

SUMMARY: A study has been made of the uptake of inositol from liquid media by Nematospora gossypii and Saccharomyces carlsbergensis 4228. All the available inositol was rapidly removed from the medium so long as growth continued. Small amounts were recovered from the organisms by water extraction, and up to 75% from the yeast by acid hydrolysis. This bound inositol in the yeast possessed properties resembling those of phytin. On media deficient in inositol, cell division was incomplete. No influence of inositol on the respiratory system of S. carlsbergensis could be detected. γ-Hexachlorocyclohexane inhibited growth and respiration of intact yeast cells, but not respiration of dried yeast preparations; its effect was not reversed by inositol. Streptidine, strepturea and streptamine neither inhibited growth nor could replace inositol as a growth factor.

SUMMARY: By irradiating with X-rays Acrobacter aerogenes (AlOC) in the dry state, mutants have been obtained differing from the parent strain in specific growth-factor requirements. About half of the mutants differ from the parent, not in having an absolute requirement for a nutrilite, but in having a longer lag-phase without it.

SUMMARY: Conditions for haemolysis by Bacterium coli have been investigated. The haemolytic factor is specific to haemolytic strains only, has not at present been separated from living bacterial cells, is associated with the logarithmic phase of growth, and requires for its action the presence of calcium ions.