- Volume 60, Issue 1, 1970

SUMMARY: Basidiospores of Lenzites saepiaria are not dormant and resemble vegetative mycelium in physiological properties and in the way they initiate outgrowth on a suitable substrate. Moistened spores respire significantly and autolyse in the absence of growth substrates; glucose, acetate or succinate are oxidized without lag. Optimal germinants, such as malt extract, allow outgrowth of 95% of the spores in 4 to 5 hr.

Studies with [14C]leucine, [3H]uridine, [3H]thymidine, [59Fe]FeCl3 and [32P]NaH2PO4 suggest that RNA and protein are synthesized at low rates which increase immediately after addition of a medium supporting germination; synthesis of DNA and Fe-porphyrins commences after approximately 2.5 hr. During germination and outgrowth, glucose is used primarily for synthesis of cellular material and little is converted to CO2. Glucose is initially utilized by the hexose monophosphate shunt and the Embden-Meyerhof pathway becomes active as outgrowth progresses. Exogenous organic acids are utilized primarily as sources of energy or membrane synthesis; CO2 evolution is high and incorporation of these substrates into cellular components is low. Much of the incorporation may involve the fixation of CO2 produced from substrate oxidation.

SUMMARY: Studies on the galactanase produced by Phytophthora infestans were facilitated by an improved culture medium for enzyme production. The enzyme degraded potato pectin until a proportion of the galactose units were released; short oligosaccharides probably occurred among the products of the reaction. The enzyme rapidly reduced the viscosity of potato and lupin pectin solutions, with a slower concomitant release of reducing groups. In addition it released total carbohydrate more rapidly than galactose from potato cell walls; these results indicate that the enzyme is an endo glycano-hydrolase. It had a limited effect on the cohesion of discs of potato tuber tissue.

SUMMARY: Zymomonas anaerobia and Z. mobilis, grown on glucose + peptone + yeast-extract medium, degraded no endocellular carbohydrate, DNA and protein even in prolonged starvation. No significant qualitative changes in protein content during starvation were detected by disc gel electrophoresis of crude extracts. Both organisms had a high content of RNA (22% w/w) which was degraded on starvation. In Z. anaerobia RNA decreased linearly to 5% of the dry weight in 125 hr. With Z. mobilis, half the RNA was degraded in the first 24 hr of starvation after which time the decline was much slower. MgCl2 (33 mM) prevented RNA breakdown. During growth, the intracellular ATP concentration increased from 0.5 to 1.0 μg./mg. dry wt, but began to decrease exponentially in the last generation before growth ceased because of glucose exhaustion. Intracellular ATP content correlated with viability determined by slide culture. The addition of 33 mM-MgCl2 to the starvation medium did not affect ATP content, but increased viability. On prolonged starvation (up to 7 days), populations whose viability had fallen to 3% possessed unimpaired ability to produce ATP from glucose; only after even longer starvation periods was this ability impaired.

SUMMARY: The anatomy of individual colonies of Streptomyces coelicolor was studied at various developmental stages in situ by means of surface-impressions and thin sections. Young colonies consisted of substrate mycelium composed of a loose network of hyphae with uniform appearance. The uppermost cells produced the very closely packed hyphae of the aerial mycelium. Subsequently the surface layer of the aerial mycelium began to sporulate but became overgrown by young hyphae which formed a new sporulating zone above the first. The process was repeated several times. Many of the early produced spores germinated immediately. When the climax of sporulation was reached the aerial mycelium showed two trends of development: one towards spore formation (in the surface layer) and one towards lysis of non-sporulating hyphae (below the sporulating zone). Sporulation was initiated by coiling of hyphal tips which were then divided by cross walls into chains of spore-sized compartments. The basal non-sporulating parts of the hyphae disintegrated later. The most conspicuous cytological change during lysis was the appearance of large dense granules.

SUMMARY: The fine structure of the morphological events during sporulation in Streptomyces coelicolor grown on chemically defined medium was studied in electron micrographs of thin sections. During vegetative growth the young hyphae were divided into long cells by cross-walls which formed in a way comparable to those in certain other Gram-positive bacteria. Sporulation was initiated by coiling of hyphal tips, which were then divided into spore-sized compartments by special cross-walls, the ‘sporulation septa’. These were laid down as double rings attached to the hyphal wall and extending centripetally. After completion of the septa the walls thickened uniformly and the individual spores began to round off. The new wall material on the long side of the spores appeared to be deposited underneath the old parent wall; the old cell wall probably formed part of the spore wall.

SUMMARY: Cultures of N2-fixing bacteria have been isolated from the intestinal contents of humans, pigs and guinea-pigs. Acetylene-reduction tests indicate that N2-fixation may be occurring in the intestines. Best N2-fixation was by cultures provisionally identified as Klebsiella aerogenes, but other genera were also involved. All cultures fixed more N2 anaerobically than aerobically but some fixation occurred when 20% O2 was present.

SUMMARY: A rod-shaped, non-motile, Gram-negative, oxidase-positive and asaccharolytic organism found in the human nasopharynx is allotted to genus Neisseria and named Neisseria elongata. The strain M 2, which is the only isolate, is proposed as the type strain. The average guanine + cytosine (G + C) content of its DNA is 53 mole %. Genetic transformation of streptomycin resistance reveals a comparatively high compatibility with N. meningitidis and a strain designated N. flava, with ratios of interstrain to autologous transformation frequency in the range 0.01 to 0.1. On the other hand, there is no affinity in streptomycin-resistance transformation between N. elongata and members of genus Moraxella, including the old concepts N. catarrhalis and N. ovis. The family Neisseriaceae now appears to consist of two genera, Neisseria and Moraxella, each containing both coccal and rod-shaped species, which makes cell shape questionable as a highly weighted criterion in the construction of bacterial genera and higher taxa.

SUMMARY: In studies of the responses to infection by the crayfish disease fungus Aphanomyces astaci of the susceptible European crayfish Astacus astacus and the resistant Western American species Pacifastacus leniusculus, the latter was consistently more resistant to infection by injection or via aquarium water; the difference in resistance was more striking in the second method. The American crayfish was only slightly less sensitive than the European crayfish to the toxic action of large numbers of dead spores of A. astaci and to infection by living spores of another phycomycete, Entomophthora apiculata, which is not a natural parasite of crayfish. A. astacus acquired a significantly higher degree of resistance to infection by injection or via the ambient water as a result of two previous exposures to sublethal numbers of spores of the pathogenic fungus.

The two strains of Aphanomyces astaci tested behaved identically within the cuticular layer of the exoskeleton of both crayfish species, showing strain-dependent degrees of ability to penetrate and grow within the cuticle. The epicuticle offered a major barrier to penetration in both hosts. The fungus was unable to establish growth within the musculature and developed only sparsely along the ventral nerve cord of living animals of both species; fungal growth was luxurious shortly before and after the death of both crayfish. Aggregation of injected spores and their encirclement by haemocytes occurred rapidly in living Astacus astacus as well as in Pacifastacus leniusculus, but melanization of the spore aggregates and hyphal elements was considerably more pronounced in the resistant crayfish, P. leniusculus. The observations suggest the participation of at least some active processes of native and acquired resistance of crayfish to the crayfish disease fungus, particularly in the internal tissues and the epicuticle.

SUMMARY: A new class of rough mutants has been found in both Salmonella montevideo and S. minnesota. The mutants resemble phenotypically rfb mutants, having a complete lipopolysaccharide core but no O-specific material in lipopolysaccharide or as free hapten. The site of these rfe mutations is near the isoleucine and valine gene ilv, and is thus separate from the known lipopolysaccharide gene clusters rfa for the core, rfb for the O-specific side-chains, and rfc for O side-chain polymerization. The function of the rfe gene(s) is not known. It is suggested that they might participate in the utilization of the antigen carrier lipid for lipopolysaccharide synthesis, or that they might regulate the activity of rfb genes. The gene determining phosphorylation of the heptose in the lipopolysaccharide core of S. minnesota was identified as one within the rfa cluster.

SUMMARY: Glucose-limited cultures of baker's yeast growing at 25° had a maximum growth rate, saturation constant and yield constant of 0.22 hr−1, 129 μg./ml. and 0.225, respectively, whereas when growing at 38° the corresponding values were 0.25 hr−1, 300 μg./ml. and 0.204. In continuous culture, with the dilution rate fixed at 0.1 hr−1 there were no differences observed in viability, incidence of respiratory deficient mutants, cytochrome spectra or mean cell dry weights, between cultures grown at 25 and 38°. The culture grown at 25° had a smaller mean cell volume, greater yield value and nitrogen utilization. Ethanol, pyruvate and α-ketoglutarate were secreted to a greater degree in cultures grown at 38°. Yeast grown at 25° had a smaller capacity to produce carbon dioxide but greater ability to take up oxygen. Enzymes associated with glycolysis, alcohol production, tricarboxylic acid cycle and respiratory chain in organisms cultured continuously at 25 and 38° showed few important differences. The most obvious ones were those involving α-ketoglutarate as a substrate, especially α-ketoglutarate dehydrogenase. There were only small differences in adenosine phosphates and nicotinamide nucleotides. At 25° the ratio NAD/NADH was 1.5 but for organisms grown at 38° the ratio was 1.1.

SUMMARY: Various toxic and non-toxic Clostridium botulinum strains can be grouped according to DNA binding homology but not according to DNA composition. The guanine + cytosine (GC) contents of DNA from six strains were 28 to 30%. DNA binding with radioactive DNA from C. botulinum type E, MINN strain, revealed that the non-proteolytic strains type B, 17, type F, 202 and type E, DETROIT are 100% homologous to the E, MINN strain. Clostridium botulinum type E, 32, the boticin producing s 5, and the non-toxic 24 NT, 26 NT and 5 i had 58 to 78% homology with the MINN strain. Clostridium botulinum type A, 62 and 78, type B, 32, type C, 573, and non-toxic OS/E1, OS/E7 and OS/MINN strains had only 6 to 14% homology with type E, MINN. Competition experiments with unlabelled DNA confirmed these results. The studies indicate that strains which are closely related serologically and biochemically are also closely related genetically, and vice versa. The data do not support the idea of a common origin of the non-toxic os strains and C. botulinum type E. The toxic type E strains and the toxic type A, B and C strains of C. botulinum are genetically heterogenous.

SUMMARY: Six independent isoniazid-resistant mutants of Mycobacterium tuberculosis were isolated under conditions which largely ensured the selection of one-step mutants. The properties of these mutants with respect to the nicotinamide adenine dinucleotide nucleosidase (NADase) inhibitor, isoniazid uptake and peroxidase activity were studied. The uptake of isoniazid by the mutants and their sensitivity to isoniazid were increased by ethylenediaminetetra-acetic acid (EDTA) and sodium dodecylsulphate. It is suggested that EDTA and sodium dodecylsulphate bring about these effects by altering the cell permeability.

SUMMARY: A number of common carbohydrates and polyols were tested to see if they could replace the lactate requirement for the development of competence in cultures of Haemophilus influenzae. Pyruvate, fructose, and glucose, when tested in the presence of inosine, were slightly stimulatory. They gave respectively, 29, 25 and 13% of the control value obtained with inosine and lactate. Under similar test conditions, mannose, mannitol, galactose, sorbose, sorbitol, ribose, glucosamine, rhamnose, D (-) arabinose, L (+) arabinose, xylose and fucose were inactive.

In combination experiments, glucose, inosine and pyruvate, and fructose, inosine and pyruvate stimulated the development of competence to 50 to 70% of the inosine and lactate control value. Without inosine, the stimulation due to glucose and pyruvate, and fructose and pyruvate was 3 and 9%, respectively.