- Volume 6, Issue 3-4, 1952

Summary: Micrococci forming part of the marine flora, are especially important in fish spoilage. They are common in estuarine mud but rare in sea water and in marine mud of the Australian continental shelf. Non-pigmented and orange strains are most abundant; lemon-yellow strains are found in the early stage of spoilage of teleost fish, but are rare in mud. About 10 % of the cocci form packets, and these are commonest in mud. Nearly all marine micrococci are saccharolytic, hydrolyse urea, and attack asparagine, aspartic acid and alanine. The classification and taxonomic position of these cocci are discussed.

Summary: Mutants of Aerobacter aerogenes incapable of utilizing citrate (C −) were discovered in glucose cultures by a modification of the mutant-concentrating penicillin technique. These C − mutants utilize glucose as efficiently as does the wild-type (C +), despite their inability to utilize a wide range of other metabolites as carbon sources for growth, including compounds that would be oxidized if glucose were aerobically dissimilated via the Krebs cycle. The compounds that the C − mutants cannot utilize are citrate, α-ketoglutarate, glutamate, succinate, fumarate, aspartate and acetate, which are all substrates to which glucose-grown C + cells slowly adapt. A non-genetic loss of ability to grow in media containing these substrates also occurs in glucose-grown populations under certain conditions. The C − mutant can revert to the prototrophic condition directly, or indirectly by first mutating to a stable state (C − F +) in which fumarate and aspartate can be utilized whereas the other compounds cannot.

Summary: Mutations were induced in the unicellular green alga Chlamydomonas moewusii Gerloff by ultraviolet irradiation. The majority of mutants detected were slow-growing types which did not respond to organic supplements in the medium, and palmelloid forms in which flagellated cells were not produced, or only occurred in small numbers. Among biochemical mutants, one exhibited impairment of the photosynthetic mechanism, and two were vitamin-dependent, respectively requiring p-aminobenzoic acid (PABA) and aneurin for growth. Some mutants were distinguished by features of cell contents, cell form, or mode of cell division, while in others motility of the cells was restricted by the absence or paralysis of the flagella.

Summary:In Chlamydomonas moewusii the primary zygote membrane (PZM) is formed at the initiation of gamete fusion. The PZM of C. moewusii does not appear to be composed of cellulose or pectic material; it stains readily with Schiff's reagent which suggests the presence of free aldehydic groups. Several recently isolated strains of Chlamydomonas show this reaction which is presumed to be common to the genus.

Summary: Rapid multiplication of Mycobacterium tuberculosis can be obtained in Dubos medium modified by the addition of an iron salt and by the replacement of albumin fraction V by the supernatant fraction of ‘Liquoid’-treated bovine serum.

Certain strains of M. johnei can be trained to grow in this medium enriched with a glycerol extract of M. phlei.

Estimates of numbers of micro-organisms occurring in three differently manured soils, made by a direct-counting and plating technique, were compared. No correlation was found between the two methods and reasons for the large discrepancy between them are discussed. Contradictory information of the effect of external factors on soil micro-organisms can be given by the two different methods of counting.

SUMMARY: By taking advantage of the long lag period before minimal therapeutic concentrations of penicillin kill bacteria, five mutants of the K12 strain of Escherichia coli (Bacterium coli) have been isolated following ultraviolet irradiation, which were 10–50 times more sensitive to penicillin than K12. This supports the theory that development of antibiotic-resistant forms is by mutation and selection.

SUMMARY: A pseudomonad obtained from a nicotinic acid enrichment culture had a growth-factor requirement satisfied by high concentrations of nicotinic acid or by minute amounts of quinolinic acid, 3-hydroxyanthranilic acid, or nicotinamide. Nicotinic acid, kynurenin sulphate, and probably 3-hydroxyanthranilic acid, can serve as sole carbon sources. The oxidation of nicotinic acid is adaptive. The finding that low concentrations of nicotinic acid fail to satisfy the growth-factor requirement is discussed.

The paucity of records of auxotrophy in pseudomonads may reflect the selection exercised by isolation media devoid of growth factors. Pseudomonads requiring aneurin were isolated from enrichments with uracil and thymine. The utilization as carbon sources of metabolites of the anthranilic acid-tryptophan-nicotinic acid series may prove of taxonomic value in Pseudomonas.

SUMMARY: The only thermophilic actinomycetes found in composts made from lawn cuttings were members of the genus Micromonospora. The isolates obtained agreed in the main with the description of M. vulgaris (Tsiklinsky) Waksman, Umbreit & Cordon. Three strains have been studied in detail. They are true thermophiles, with an optimum range of growth 45–60°, and appear in abundance at the high-temperature phase of the compost, with a profuse production of aerial mycelium and spores. Spore germination is induced by heat activation, 5 min. at 85° securing growth under suboptimal conditions. Thin suspensions of spores in 1 % sucrose or in very dilute nutrient broth withstand 100° for periods of up to 45 min. Only very dense aqueous or saline suspensions are tolerant of these exposures. Surface growth on cellophan bearing a high density of aerial mycelium and spores withstands dry heating at 100° for 150 min. or at 106° for 5 min.

SUMMARY:Penicillium patulum, Aspergillus clavatus and A. terreus produced antibiotic substances when grown on organic materials which are used or could be used as manures. The addition of glucose increased the antibiotic titre in every case.

Antibiotics were also formed in autoclaved soils enriched with easily available carbon sources and inoculated with one of the following fungi: P. patulum, A. clavatus, A. terreus and two unidentified species of Penicillium. P. patulum formed an antibiotic also on partially sterilized supplemented soil. The degree of antibiotic activity was decreased when soil cultures of P. patulum were contaminated with other organisms from soil or from the air, but even gross contamination with natural soil at 25° did not destroy activity entirely until 11 days had elapsed. Loss of activity was smaller at lower temperatures.

Summary:An examination of Giemsa-stained preparations of lung tissue and peritoneal fluid from mice inoculated with Haemophilus pertussis shows that the bacillary form can change to the L-form of the organism in vivo. This transformation is more rapid and more complete in immune than in normal mice. The L-form, produced on Bordet-Gengou agar containing 1·5% (w/v) glycine, administered intranasally can revert to the bacillary form in vivo.

SUMMARY: Eleven strains regarded as moraxellas were studied; nine were characterized by moderate growth on the usual media, a positive oxidase reaction and sensitivity to penicillin, and six of these preferred or required a humid atmosphere when incubated at 37°. The classification of these strains was considered correct. Two strains did not show any of these characteristics, and it was concluded that they should not properly be classified as moraxellas.

A positive oxidase reaction, sensitivity to penicillin, and preference for a humid atmosphere at 37° may be useful criteria in the classification of Moraxella. It is suggested that Moraxella may be closely related to Neisseria, and that the description of the genus and its taxonomic position should be revised in accordance with Lwoff’s proposals.

Mima polymorpha var. oxidans (De Bord) is believed to belong to Moraxella, whereas other members of the tribe Mimeae (De Bord) and Bacterium anitratum (Schaub & Hauber) are probably not closely related to Moraxella.

SUMMARY: The simultaneous uptake of CO2, H2, and O2 by non-proliferating cells of Hydrogenomonas facilis was studied by means of a new method employing ordinary Warburg vessels each provided with one stopper side-arm and one vent side-arm. H. facilis effected the same overall reaction as that carried out by certain anaerobically adapted green algae: 6H2 + 2O2 + CO2 → (CH2O) + 5H2O. In an atmosphere of CO2 and H2, no CO2 fixation accompanied the quantitative reduction of nitrate to nitrite by molecular H2; nor was there any change in concentration of bicarbonate or in total gas pressure when acetone, pyruvate, or α-ketoglutarate were added.

SUMMARY: Spore-inoculated penicillin fermentations using Penicillium chrysogenum W48–701 were carried out in two different types of equipment: stirred and aerated laboratory fermentors, or shaken flasks. The respiration of the mycelium was measured in Warburg manometers. The maximum oxygen demand in the fermentations occurred at approximately 40 hr. and the maximum Q O2 of the mycelium at 24 hr. or earlier. During the whole phase of penicillin formation, respiration decreased steadily. Mycelium grown in the stirred and aerated vessels showed the highest respiration rate. In the shaken flasks the rate of solution of oxygen in the medium was found by polarographic methods to be insufficient to allow a respiration rate as high as that which occurred in the stirred and aerated vessels. Respiration in shaken flasks, however, was not directly limited by the rate of solution of oxygen but by the amount and kind of the respiratory enzymes which appear to be synthesized in proportion to the concentration of dissolved oxygen present during early growth.

Whereas the respiratory quotient (r.q.) of mycelium from shaken-flask fermentations remained approximately unity throughout the fermentation, in the stirred and aerated vessels the r.q. of the mycelium fell from unity to as low as 0·57, during the fermentation. The degree of aeration therefore appears to influence not only the quantity but also the kind of respiratory enzymes synthesized.

SUMMARY: A bacteriolytic protease produced by a species of Streptomyces is activated by manganese and other metals. This enzyme digests autoclaved Bacterium coli but not autoclaved Staphylococcus aureus, though it does digest ‘protein’ extracted from staphylococci with hot alkali. A ribonuclease is produced by the Streptomyces sp. but it apparently takes no part in the lysis of Staph, aureus. During lysis autoclaved Bact. coli do not disintegrate but progressively diminish in size.

SUMMARY: When young cells of a strain of a staphylococcus were exposed to substances noxious to the organism, variations transmissible to progeny were obtained. The variations consisted mainly in a decrease in antibiotic resistance and mouse virulence. Characters of pathogenic strains such as coagulase production, mannitol fermentation and gelatin liquefaction were also abolished.

The experiments were carried out in a way that excluded the selection of spontaneous mutants. Adaptation should also be excluded as all variations consisted in a loss or decrease of activities.

The variants when first isolated seemed unhealthy, the largest part of their progeny being non-viable and consisting of cells which grew up to a point and lysed without dividing. The results obtained were therefore attributed to a damage of the parent cell caused by the injurious agents used.

SUMMARY: Three yeast species, Rhodotorula mucilaginosa, Trichosporon cutaneum and Torulopsis albida (Cryptococcus albidus) respond in a simple auxanographic spot test to the presence of aneurin, aneurin split products and cocarboxylase. Differences in the behaviour of these three species towards the different biologically active entities make it possible to differentiate between these substances and to identify them. Moreover, from the appearance of the auxanogram conclusions can be drawn regarding certain dynamic aspects of aneurin metabolism such as velocity of uptake, storage and splitting of aneurin, or of its derivatives. The test is not only qualitative but also, within certain limits, quantitative.

SUMMARY : A strain of Bacillus cereus known to produce penicillinase adaptively was tested for penicillin sensitivity at different temperatures. With small inocula, the organisms grew freely at 37° in concentrations of penicillin up to a hundred times greater than those which completely suppressed their growth at 42°. This difference in apparent sensitivity almost disappeared when the inoculum was very heavy or consisted of cells which had been allowed to adapt by previous growth in the presence of penicillin.

SUMMARY : Three species of homofermentative lactobacilli, identified as Lactobacillus delbrueckii, L. plantarum and L. leichmannii have been found to be of widespread occurrence on apples and in the expressed juice. Precautions must be taken to arrest their development during the processing of apples intended for the production of unfermented apple juice, otherwise the juice will be rendered unpalatable through development of excess acidity.