- Volume 4, Issue 2, 1950

SUMMARY: Culture fluids of fifty-two strains of Fusarium spp. were examined for antibacterial activity. Four groups were distinguished: (a) six strains equally active against a strain of Staphylococcus aureus and Mycobacterium phlei strain 1; (b) sixteen strains much less active against Staph. aureus than against Myco. phlei 1; (c) fourteen strains inactive against Staph. aureus, active against Myco. phlei 1; (d) sixteen strains inactive against both Staph. aureus and Myco. phlei 1, of which six were active against Myco. phlei strain 2.

Examination of pure antibiotic substances isolated from the culture fluids of nine of the strains showed them to be both bacteriostatic and bactericidal; they were very active against mycobacteria and effective to a lesser degree against other Gram-positive bacteria. They were ineffective against Gram-negative bacteria and fungi.

SUMMARY: The effect of temperature and some chemical substances on the fruiting of strains of nine species of Chaetomium was studied. The optimum temperature for fruiting was generally lower than that for growth. Micro-nutrients of the nature of growth factors and starvation with respect to nutrients may both stimulate fruiting, whereas staling inhibits it, the ultimate balance between these effects determining the fruiting behaviour of a given species. These factors had no significant effect on the final amount of the vegetative growth within the conditions of the experiments.

SUMMARY: Variants whose growth was either dependent upon or enhanced by streptomycin appeared spontaneously during a sensitivity titration of a strain of Staphylococcus aureus isolated from a nose and throat culture. In addition to these variants, multiple single colony strains from the original culture exhibited a wide range of susceptibility to streptomycin. The variability after exposure to streptomycin in the laboratory was no greater than that exhibited by the original isolates.

The mechanism by which these variants utilize streptomycin is not yet known. Streptomycin inactivated by semicarbazide or l-cysteine did not support or enhance growth. The acquisition of the ability to utilize streptomycin had no measurable effect on the other biochemical characteristics investigated.

When large inocula of the dependent variant were planted on streptomyein-free agar, a few colonies appeared after prolonged incubation. The cells of such colonies underwent a profound morphologic change not unlike the production of ‘large bodies’ which occurs in several species of bacilli. The progeny of such colonies were of normal morphology and either resistant or susceptible to streptomycin but were no longer dependent on it.

Survival of the variants in chick embryos, except in those instances where mutation occurred, was dependent upon the presence of streptomycin. These variants were mouse avirulent, even in the presence of hog mucin in addition to streptomycin.

SUMMARY: Certain single-cell strains of brewer’s top fermentation yeasts require p-aminobenzoic acid as an essential nutrient. Relatively large quantities of adenine, together with certain amino-acids, of which methionine and histidine were of prime importance, could substitute for the p-aminobenzoic acid.

In the presence of adenine, histidine, and suboptimal amounts of methionine, the addition of any one of seven other amino-acids caused a marked stimulation of growth. These amino-acids were leucine, isoleucine, norleucine, valine, norvaline, tyrosine and phenylalanine.

SUMMARY: Strains of Group A streptococci produced an extracellular carbohydrase which degraded starch. The enzyme in crude undialysed culture filtrates bore a general resemblance to pancreatic diastase. Amylolytic activity was decreased in environmental conditions which also affected streptococcal proteinase, namely in cultures grown at 23°, in filtered broth, or after serial mouse passage. Amylase production was associated with hyaluronidase production in strains having the type-specific M antigen 4, or the non-specific T antigen 4, whereas proteinase-positive strains of the same group of closely related specific Types 4, 24, 26, 28, 29, 46 were usually amylase-negative; but the association between production of any two of the three enzymes was not complete. Hyaluronidase-positive Type 22 strains did not produce amylase, and with two exceptions, a Type 2 strain and a strain serologically unidentified, other representative serological types were amylase-negative, though some strains degraded starch in growing cultures.

SUMMARY: The power of fermentation by yeast cells was decreased when the cultures were grown in media deficient in any of seven essential growth factors. A rapid increase in the rate of fermentation upon the addition of a growth factor was obtained in every case except that of inositol, where the response was much slower. The absence of a nitrogen source decreased the response to biotin, pantothenic acid or pyridoxin to a much greater extent than to aneurin or nicotinic acid. Differences were noted also in the behaviour of the two groups towards sodium azide, which can be explained on the assumption that biotin, pantothenic acid and pyridoxin affect fermentation only in a relatively indirect manner.

The decrease in the power of fermentation produced by pyridoxin deficiency was not observed until the pyridoxin content of the cells was only about one-fifth of the normal. Such yeast showed also an enhanced Pasteur effect. Pyridoxin deficiency produced no decrease in the proportion of glucose assimilated by resting cells.

SUMMARY: Nitrosomonas europaea (Winogradsky) was isolated in pure culture from Rothamsted soil. The method used entailed: (1) building up the population of nitrifiers in enrichment cultures; (2) removal of the cells from the chalk in an enriched culture with a stream of carbon dioxide; (3) picking colonies from poured silica gel plates.

SUMMARY: A new species of Acetobacter, A. acidum-mucosum, isolated from a sample of brewery yeast is proposed. In a malt extract medium at pH 4·5 or lower it forms large capsules and a voluminous viscid sediment, whereas at pH values above 4·9 the capsules are smaller and the deposit is powdery. Its ability to form a starch-like polysaccharide is a characteristic which has not been noted in the case of any other species of Acetobacter.

SUMMARY: Lineola, a new bacterial genus, is characterized by large and very long cells of an unusual type and by the formation of motile trichomes of considerable length which may be branched.

Two species were isolated in pure culture by the use of capillary pipettes. Even when their nutritional requirements were known it was difficult to purify them by plating. The growths of the two species on agar are different because the trichomes of L. articulata are much softer than those of L. longa.

The cells of both species contain a large number of nucleoids and divide by constriction. In L. longa the daughter cells remain firmly connected, whereas in L. articulata the links become pliable, the whole chain-like trichome bending when swimming. Both species are Gram-negative and have numerous flagella. No spores were found.

Media with peptone, meat extract, yeast extract, and the like must be supplemented with acetate and with agar or certain other substances, to support multiplication.

SUMMARY: With the aid of abrasives, paracrinkle virus, hitherto transmitted only by grafting, was transmitted to Arran Victory potatoes by inoculation with sap from infected plants, either symptomless King Edward or diseased Arran Victory. The proportion of plants that became infected was increased when they were kept in darkness for some days before inoculation.

Tomato plants were more readily infected than Arran Victory potatoes, no abrasive being needed. Infected tomatoes were symptomless, but electron microscopy showed their sap to contain rod-shaped particles of variable lengths and about 10 mμ. wide. Such particles have not been found in uninfected tomatoes and they are presumed to be the virus; they were destroyed by heating at 60°.

The nature of similar particles in King Edward and Arran Victory potatoes with paracrinkle is uncertain, because rod-shaped particles were also found in uninfected Arran Victory. Rod-shaped particles also occurred in uninfected plants of all other potato varieties examined and in newly raised potato seedlings; they were not transmitted, either by inoculation or by grafting, to tomato or other hosts tested, and they withstood heating to 98°.

These results with paracrinkle parallel those with certain other plant viruses. They invalidate theories that postulate its origin as a consequence of grafting and render unnecessary the concept that it is intrinsic to King Edward potatoes.

SUMMARY: Electron micrographs of potato virus X, show tenuous rod-shaped particles of variable length but constant width of about 10 mμ. Lightly shadowed rods lying along the direction of shadowing show a regular cross banding at intervals of about 10 mμ. Attempts to purify the virus cause the particles to aggregate and become entwined to form extensive rope- and net-like structures. This aggregation may be responsible for the loss of solubility that often accompanies purification, though similar structures are visible in micrographs of both soluble and insoluble preparations of the purified virus. Hydrolysis by chymotrypsin yields products too small to be resolvable, and the material remaining after most of a preparation has been hydrolysed appears similar to that in unincubated preparations.

SUMMARY: The method of estimating potency of lethal substances by determining death times was applied to the titration of the virus isolated from a case of bovine Lumpy Skin Disease. It was more reliable than that based on the occurrence of recognizable lesions in the embryo after amniotic inoculation.

The method was used to demonstrate the growth of virus in tissues other than skin epithelium, to determine the susceptibility of the virus to destruction by heat, and for the demonstration of neutralizing antibody.

Neutralizing antibody was found in convalescent bovine sera. Normal sera from a variety of animal species including bovines feebly neutralized the virus. This feeble neutralization may indicate the presence in sera of virus-inhibiting substances other than antibody or, in the case of bovines, antibody acquired as a result of inapparent infection.

SUMMARY: A base exchange column for the preparation of silica sols is described. Sols prepared by the method can be sterilized by heat treatment and are stable for some weeks. Bacteriological media can easily be prepared with such sols and the gelling time regulated by the concentration of sodium chloride used.

SUMMARY: Examination by paper partition chromatography of casein-hydrolysate/glucose culture filtrates of forty-seven strains of coliform organisms indicates that the decarboxylation of glutamic acid is characteristic of Wilson's Bacterium coli Type I.

SUMMARY: The filamentous forms of fowl-plague virus, isolated from infected eggs by Elford and Dawson, may be similar in origin to the stalked forms of vaccinia virus discovered in preparations of infected cells by Bland & Robinow, who contended that they were elementary bodies attached to cytoplasmic threads derived from the host cell.

SUMMARY: Under standard conditions of subculturing in increasing drug concentrations, licheniformin and subtilin (polypeptide-containing antibiotics from the genus Bacillus) induced resistance in Mycobacterium phlei more slowly and to a much smaller degree than did streptomycin. Strains resistant to licheniformin and subtilin tended to revert, whereas streptomycin-resistance was stable. Licheniformin resistance was somewhat more difficult to induce and less stable than subtilin resistance.

Cross-resistance tests of bacteriostatic activity between the resistant strains and the three antibiotics distinguished completely licheniformin from both subtilin and streptomycin. Although the difference between licheniformin and subtilin was largely confirmed by a more sensitive bactericidal test, making viable counts after varying periods of exposure of the resistant strains to the antibioties in nutrient medium, the test, nevertheless, revealed a minor overlap between the two antibiotics, which was either the result of contamination of one by the other or, more probably, the expression of some common chemical property. Licheniformin and subtilin differed in the speed of their lethal action on M. phlei, subtilin being much the slower.

When M. phlei was exposed to mixtures of streptomycin and licheniformin in certain proportions, the rapid development of high streptomycin resistance, was prevented.

SUMMARY: Microbes were grown on microscope slides so that the growth could readily be observed by phase-contrast microscopy.

Proteus vulgaris, grown on agar containing penicillin, undergoes extraordinary morphological changes which vary with the temperature of incubation, the concentration of the penicillin, the concentration of the agar and the presence of small amounts of fluid between the agar and the cover-slip. The bacilli may divide normally once or twice into elements that grow without dividing and which may develop into fantastically shaped thread or swollen forms. In high concentrations of penicillin the fantastic shapes are obtained by enlargement without division. At first the nuclei divide as in normal organisms. The thread forms have condensed nuclei arranged in alternating pattern along the side of the cells. In the swellings there may be either nuclear material filling the cells, a condensed central mass or a reticulum. When vacuoles are present these displace the nuclear material.

When the misshapen organisms are transferred to a medium free from penicillin and containing penicillinase they divide, forming normal bacilli. Many of the swollen elements burst and disappear.

The motility of the greatly enlarged organisms is sluggish, and flagellar movement can clearly be observed by phase contrast. The movement of the flagella of the organisms responds readily to radiant heat, and a careful study of these movements makes it impossible to accept Pijper’s contention that bacterial motility is due entirely to undulatory movements of the body and that the flagella are merely mucoid strands cast off as the result of motility.

The flagella were demonstrated in the large forms by fixing the culture through the agar for several days, detaching the agar and staining the cover-slip, which carries the fixed colony, with a saturated watery solution of night blue. The nuclei were shown by treating films with hot nitric acid, washing and staining first with cresyl blue then Leishman’s stain.

SUMMARY: Certain batches of nutrient agar were inhibitory to small inocula of Shigella dysenteriae. The inhibitory effect was abolished by catalase and by manganese dioxide. It occurred only with surface cultures incubated aerobically; poured plates or plates incubated anaerobically showed no inhibition. The inhibitor was a peroxide formed during the heating of nutrient broth and agar; it was present in minimal inhibitory concentrations since dilution with one to four volumes of saline agar removed the inhibition. It is suggested that some nutrient agars contain material which, on exposure to air, forms inhibitory concentrations of peroxide in the surface layer.