- Volume 35, Issue 3, 1964

SUMMARY: A number of isolates, giving the morphological cultural and biochemical reactions of Moraxella liquefaciens, were obtained from the conjunctiva of healthy guinea pigs. Antigenically they form a single group divisible into two types. No antigenic relationship to known Moraxella species could be demonstrated. The organisms appear to be natural parasites of the guinea pig. No similar organisms were isolated from a small number of wild house mice examined.

SUMMARY: An electron microscopic investigation was carried out on thin sections of both S and R variants of Brucella abortus, strain sa: no ultrastructural differences were noted between the two variants.

The cells are limited by a cell wall, comprising an outer triple-layered membrane (65–80 Å. thick) and an inner homogeneous layer of variable thickness, and a triple-layered cytoplasmic membrane about 70 Å. thick. The cytoplasm and nucleoplasm of brucellae are similar to those of other bacteria. A characteristic feature of these organisms is the presence of membranous structures (300–800 Å. in diameter) associated with the cytoplasmic membrane. These “peripheral formations”, which occur singly or in clusters, do not appear to arise by obvious invagination of the cytoplasmic membrane.

No evidence has been obtained for the existence of capsules in virulent brucellae.

SUMMARY: Cells of Brucella abortus, strain sa-s, grown within normal guinea-pig monocytes maintained in vitro, were examined by electron microscopy. Intracellular multiplication of brucellae was followed for 48 hr. During the entire period of observation the bacteria were present in the cytoplasm of the monocytes, localized within vacuoles limited by a “unit membrane”.

No obvious ultrastructural differences (particularly in surface structures) were detected between monocyte-grown bacteria and sister cells cultivated on a lifeless medium, which might account for the known differences between the two (e.g. differences in resistance to serum bactericidal factors and in intracellular growth patterns).

In spite of the large numbers of intracellular parasites present the host cells did not show evident structural modifications.

Some observations made on intracellular B. abortus, strain sa-r, showed that after up to 24 hr within guinea-pig monocytes most of the bacteria had retained their morphological integrity and were indistinguishable from R organisms grown on agar.

SUMMARY: The rates of formation of transformed cells in mixtures of transforming DNA and transformable Haemophilus influenzae bacteria have been measured. The data were interpreted as follows. About 4–5 sec. are required for the penetration of a DNA particle of 8–9 × 106 mean molecular weight. The average number of penetration sites per bacterium is probably two. There is no reversible attachment of DNA to these sites. Crude calculations show that about one out of every two encounters between a bacterium and a DNA molecule results in the penetration of the latter into the cell.

SUMMARY: The effect of cultural conditions on the growth and nitrate reductase activity of a bacterium, now identified as Photobacterium sepia, were examined. The bacterium grew well with ammonium chloride, ammonium nitrate or potassium nitrate as sole nitrogen source. Nitrate reductase activity was markedly decreased in organisms deficient in molybdenum or iron and in organisms grown at high oxygen pressures. The P. sepia enzyme is thus similar to nitrate reductases from other bacteria. The P. sepia enzyme is constitutive; it is present in organisms grown with ammonium chloride in the absence of nitrate; the ammonium radical did not depress enzyme activity. Under certain conditions (NH4NO3 medium, 10%, v/v, O2 in N2) molybdenum (10 μg./l.) depressed the nitrate reductase activity, but this effect was annulled by repeated subcultivation in molybdenum-deficient medium. Vanadium and especially tungsten, also inhibited the enzyme. The uptake of nitric oxide was decreased in organisms depleted of iron but was increased in organisms deficient in molybdenum. The behaviour of nitrate reductase preparations during fractionation whether from P. sepia grown with KNO3 or with NH4Cl suggests that the enzyme is the same from both sources.

SUMMARY: Growth of a biotin-requiring strain of Saccharomyces cerevisiae in a medium containing a suboptimal concentration of biotin caused changes in the fine structure of the yeast as revealed by electron microscopy. The cytoplasmic and vacuolar membranes in yeast grown in unsupplemented biotin-deficient medium were particularly susceptible to polymerization damage and appeared to split along the lipid layer. Similar changes in the appearance of the cytoplasmic membrane were observed in biotin-optimal yeast after treatment with aqueous butanol. Yeast grown in unsupplemented biotin-deficient medium also contained a slightly greater number of large storage granules as compared with exponential phase biotinoptimal yeast. When grown in aspartate-supplemented biotin-deficient medium, the yeast had much thicker cell walls than when grown in unsupplemented biotin-deficient medium. In yeast grown in oleate-supplemented biotin-deficient medium, the cytoplasmic membrane split less extensively along the lipid layer as compared with yeast grown in unsupplemented biotin-deficient medium. Organisms grown in biotin-deficient medium supplemented with aspartate + oleate resembled those grown in biotin-deficient medium supplemented with only aspartate in possessing thick cell walls, but otherwise were similar in fine structure to yeast grown in oleate-supplemented biotin-deficient medium. The storage granules in yeast grown in biotin-optimal medium and in unsupplemented biotin-deficient medium stained strongly with Sudan Black B, a lipophilic stain, and their appearance in increased numbers in yeast grown in unsupplemented biotin-deficient medium was accompanied by an increase in the lipid content of the yeast as compared with biotin-optimal yeast. The significance of these changes in fine structure is discussed in relation to changes in chemical composition previously reported to result from an imposition of biotin deficiency in the yeast.

SUMMARY: Cell walls of two smooth strains of Salmonella typhimurium and their derived rough variants were found to be very similar in composition as determined by analyses for nitrogen, phosphorus, hexosamine and lipid. The rough cell walls contained less reducing substance than their parent smooth forms, 3∙8% against 15∙6% and 4∙2% against 10∙7% (w/w). The sugar components common to rough and smooth cell walls were glucose, hexosamine, heptose and a 2-keto-3 deoxy sugar. In addition smooth cell walls possessed rhamnose, abequose and a larger content of mannose and glucose. Treatment with sodium lauryl sulphate produced a greater decrease in the extinction of suspensions of smooth walls than of rough cell walls. Rough cell walls were more susceptible than smooth to lysis by an ethylenediamine tetra-acetate (EDTA) + lysozyme system.

SUMMARY: A new isolate of Neurospora crassa displays a rhythm in its growth pattern. As the mycelium grows along the surface of the medium it begins, after the 12th hr, to form aerial hyphae at the growing front. This aerial growth continues until the 24th hr of growth and then stops. Surface growth continues until about the 32nd hr, when aerial hyphae are again formed. This alternation of surface and aerial hyphae results in a colony with zones or bands of mycelia of different densities. The rhythm is circadian, about 24 hr, and is perpetuated under conditions of constant light, temperature and humidity. The rhythm has remained steady in continuous darkness for over 2 months. Banding can be somewhat influenced by temperature and light but is not synchronized by these factors. A heat sensitive factor can be isolated from the growth medium which will eliminate the rhythm.

SUMMARY: The morphogenesis of organized thalli in pure cultures of Nostoc muscorum a was found to be dependent upon the sequential differentiation of specialized cells and filaments. In a culture of N. muscorum previously kept in darkness, a brief exposure to light induced development during subsequent incubation in darkness, and resulted in the formation of simple unbranched thalli. Such structures are interpreted as being the product of a single complete turn of the developmental cycle. Continuous illumination produces ramified thalli (dendroid macrostructures) which bend toward the source of light. The various differentiated cell and filament stages of development are oriented within the dendroid thallus. The presence of glucose in culture media prolongs growth at the heterocystous filament stage. The consequent inability to form motile hormogonia leads to the growth of a thallus lacking an ordered macroscopic structure. The term lanose structure is applied to this form to describe its fleece-like appearance.

Hormogone development in cultures of Nostoc muscorum a appears to be sensitive to a metabolic product. In cultures containing glucose this product is formed rapidly, hence a lanose macrostructure results. In cultures containing sucrose, the breakdown of organized thalli and formation of a lanose macrostructure takes place only after prolonged incubation. It is suggested that the pattern of organization in other, more complex, cyanophycean colonies may arise similarly from a photo-induced sequence of cellular and filamentous development.

SUMMARY: An unidentified Pseudomonas capable of growth on ferrichromes as sole sources of carbon and nitrogen was isolated by enrichment culture on ferrichrome A. The spectral shifts observed for the culture supernatant fluids and the degradation products which accumulated in the culture media during growth on these compounds indicated that initially the cyclic peptide rings are broken to yield simpler hydroxamates. These simpler hydroxamates were then deacylated, perhaps after reduction to the corresponding N-substituted amides.

SUMMARY: The structure of filamentous phages and RNA-containing phages, both specific for male strains of Escherichia coli, is described in detail. The RNA phages are probably in the form of icosahedra comprising 92 morphological sub-units. The filamentous type consists of a protein coat containing a nucleic acid core which is visible in negative stained preparations. A new morphological type of coliphage isolated on a male strain of E. coli is described and the manner in which the tail is attached to the head is shown in electron micrographs. Two temperate phages from male strains are studied in detail; their head sub-units are shown to number 325 and are arranged in the form of an octahedron.

SUMMARY: Aspergillus rugulosus, a member of the A. nidulans group of fungi, produces a number of complex phenolic metabolites. In the course of studies towards the elucidation of the biosynthesis of these compounds, we have undertaken an investigation of linkage which involved conventional genetic markers together with phenol-biosynthesis characters. This led to the observation that there was a direct relationship between a morphological character, designated ‘fluffy’, and the production of a particular complex phenolic compound.

SUMMARY: During the investigation of procedures for the isolation and characterization of the agent causing scrapie disease in sheep a study of the elution behaviour of scrapie brain preparations from sheep, goats and mice on calcium phosphate columns was made. Eluates of increasing phosphate concentration were tested for biological activity in the sheep and mouse. Adsorption on calcium phosphate columns did not provide a satisfactory method for concentration of the biologically active scrapie agent from untreated homogenates; only a 10-fold purification of the agent was achieved. The activity always appeared in the pelleted sediment after high-speed centrifugation of the eluates. Ether treatment of the tissue can alter the elution behaviour. The elution data have been interpreted as indicating species variation in the binding of the agent to brain tissue.

SUMMARY: Genes determining the flagellar antigens were introduced from Hfr Salmonella abony into F− Escherichia coli by sexual recombination. The gene H1 for the phase-1 flagellar antigen of Salmonella was found to be allelic to H, the gene for the only flagellar antigen of E. coli. The phase-2 antigen of Salmonella has no counterpart in E. coli; if the corresponding salmonella gene H2 is introduced in E. coli, diphasic strains are produced whose phase-2 antigen is that of the Salmonella parent; the phase-1 antigen can be that of either parent. In each case the diphasic strains undergo a true phase variation, with either the phase-1 or the phase-2 antigen being expressed at one time. The rates of this variation are comparable to those in the Salmonella parent.

SUMMARY: The application of computer techniques to study a group of organisms comprising 83 strains of the genus Rhizobium and 38 strains belonging to the genera Agrobacterium, Chromobacterium, Beijerinckia and Bacillus is described. One hundred different features including vitamin, carbohydrate and nitrogen nutrition, antibiotic sensitivities, morphological and colonial characteristics, and infective attributes were used to determine the relationships between these organisms. Members of the genera Chromobacterium, Bacillus and Beijerinckia showed little affinity with the other species studied, or with each other. The results obtained for the genus Rhizobium indicate the need for major taxonomic changes. These changes would include: (1) the consolidation of R. trifolii, R. leguminosarum and R. phaseoli into a single species, R. leguminosarum; (2) The consolidation of A. radiobacter and A. tumefaciens and their inclusion as R. radiobacter in the genus Rhizobium. The creation of a new genus Phytomyxa to contain strains of slow-growing root-nodule bacteria is also proposed.

SUMMARY: The biochemical and physiological characters of 28 strains of motile lactobacilli isolated from silage, and of two motile strains of Lactobacillus salivarius, are described. The silage organisms belong to the homofermentative low-temperature group but their properties are different from those of L. casei and L. plantarum. Flagella-stained preparations and electron micrographs of two strains show that they have numerous peritrichous flagella.