- Volume 73, Issue 3, 1972

SUMMARY: Arginine biosynthesis in Pseudomonas aeruginosa proceeded via transacetylation of acetylornithine with glutamate; it resembled Micrococcus glutamicus rather than Escherichia coli. Of four arginine biosynthetic enzymes, N-acetyl-y-glutamokinase, N-acetylornithine glutamate transacetylase, ornithine transcarbamylase and argininosuccinase determined under various conditions of arginine excess and deprivation, only ornithine transcarbamylase (OTCase) varied. It appeared to be fully derepressed in the wild-type strain grown in minimal medium and partially repressed in the presence of arginine. OTCase was also partially repressed in all arginine auxotrophs, even when deprived of arginine. OTCase was derepressed in bradytrophic revertants of arginine auxotrophs grown in minimal medium, but its level was never greater than that in the wild-type. The level of endogenous arginine in the wild-type strain grown in minimal medium is probably insufficient to effect repression. Exogenous arginine is more effective in repression when present as the sole carbon source.

SUMMARY: The extracellular polygalacturonate lyase of a Bacillus species isolated from water-stored Sitka spruce (Picea sitchensis) was purified by ammonium sulphate fractionation and CM-cellulose chromatography. Its specific activity increased 59-fold and amylase, protease and xylanase activities were removed.

Degradation of the substrate was accompanied by a large decrease in viscosity, suggesting random attack. While calcium and strontium ions activated the enzyme, most divalent cations caused inhibition. Addition of EDTA resulted in complete inactivation. Enzyme activity was higher with acid soluble pectic acid than with sodium polypectate. The purified enzyme was stable over a wide pH range and had considerable resistance to thermal inactivation. This stability explains the enzyme's prolonged activity in water-stored spruce sapwood.

SUMMARY: A correlation has been observed in strains of Escherichia coli between the Ion phenotype and the capacity to support the growth of Dictyostelium discoideum amoebae. lon + strains, E. coli B/r Ion sul and E. coli K12 lon + strain, when used as the food source, yielded approximately four times the number of amoebae as the Ion- strains, E. coli B and E. coli K-12 AB1899.

The differences in yield may be caused by the release of an extracellular inhibitor of the growth of slime-mould amoebae by the Ion strains. Interaction with this Ion phenotype effect was observed with the DNA repair mutants exrA, recA or uvr. The effect of the inhibitor release on the yield of amoebae in E. coli B or E. coli Bs-2 was partially modified by conjugation into these strains of the sex factor F' lon +.

Reduced ability to support growth of slime-mould amoebae and high sensitivity to the antibacterial agent crystal violet appear to be properties specific to filamentous lon- strains. Two possible sites in the bacteria are suggested which may be involved in expression of the Ion phenotype.

SUMMARY: Bacteria of the acidovorans Pseudomonas group (Pseudomonas acidovorans and P. testosteroni) utilize β-carboxy-cis, cis-muconate for growth via the β-ketoadipate pathway. Since protocatechuate, the only known metabolic precursor of β-carboxy-cis, cis-muconate, is utilized by these bacteria via another metabolic pathway, it appears that aa-carboxy-cis, cis-muconate can serve as a natural growth substrate.

The members of the acidovorans group are freely permeable to β-carboxy-cis, cis-muconate and in this respect they differ from other Pseudomonas species.

Unlike other bacteria (Acinetobacter, Alcaligenes, Nocardia and other species of Pseudomonas) the acidovorans group of Pseudomonas do not use protocatechuate or β-ketoadipate as an inducer of β-carboxy-cis, cis-mucortate lactonizing enzyme and y-carboxy muconolactone decarboxylase. In Pseudomonas acidovorans and P. testosteroni the inducer of these enzymes appears to be β-carboxy-cis, cis-muconate (or y-carboxymuconolactone). In P. testosteroni, but not in P. acidovorans, aa-ketoadipate serves as an inducer of muconolactone isomerase. Therefore strains of P. acidovorans and P. testosteroni may be identified by the unique mechanism that they employ to govern synthesis of the enzymes of the β-ketoadipate pathway.

SUMMARY: Thermoplasma acidophila is a free-living Mycoplasma which grows optimally at a temperature of 55 °C and a pH value of 2.0. Thermoplasma acidophila strains are resistant to lysis when suspended in distilled water. Organisms are also more resistant than other reported mycoplasmas to lysis by anionic and cationic surface active agents. Bacterial suspensions were unusually resistant to thermal lysis and were not affected even at temperatures of 100 βC. Although lysis did not occur at pH ranges of 1 to 7, rapid lysis occurred at pH values of 8 and above. These findings suggest that T. acidophila has an unusual membrane structure enabling this Mycoplasma to grow at high temperature and low pH.

SUMMARY: Germination of the endospores of the thermophilic actinomycete Thermoactinomyces vulgaris (isolate CUB337) was observed by means of phase-contrast and electron microscopy. The first cytological change was the appearance of four fibrillar regions in the core. During germination the core became granular in texture and swollen, the cortex became laminated and later uniformly reduced to a thin layer. At this late stage of germination and before outgrowth, layers external to the cortex also showed signs of breakdown. The endospores were induced to germinate by 10 mM solutions of L-leucine, L-β-phenylalanine, L-alanine, L-α-amino butyric acid, L-valine, L-methionine, L-cystine, L-β-asparagine, inosine, adenosine and by 1 mM-N-dodecylamine. The effect of heat treatment in general decreased germination but a period of storage increased germination. Outgrowth was inhibited by nisin but was less sensitive to novobiocin than was outgrowth in Bacillus coagulans.

The response of isolate CUB337 to germinant compounds resembled that of Bacillus cereus but when endospores of nine other Thermoactinomyces vulgaris isolates were tested, considerable strain variation was observed.

SUMMARY: Ten isolates of Sclerotium rolfsii were divided into two types (R and A) which differed in their response to factors affecting sclerotium formation. It is suggested that differences in carbohydrate metabolism may account for the differences between them.

SUMMARY: A wide diversity of treatments can cause rapid and extensive bursting of hyphal tips of Mucor rouxii. Most hyphal tips from colonies grown on full-strength agar medium burst readily when flooded with distilled water. In contrast, hyphal tips from colonies grown on diluted medium survived flooding with distilled water but succumbed to dilute aqueous solutions (particularly acids, but also neutral salts, EDTA, alcohols, acetone, detergents). Apex bursting was generally inhibited by alkaline solutions but took place at certain concentrations of ethanolamine or NH40OH. Mg2+, Mn2+ or Ca2+ caused pronounced swelling of the hyphal apex followed by an occasional burst. Sharp temperature increases also brought about apical disintegration regardless of nutrient concentration.

Colonies of Aspergillus fumigatus, Fusarium sp., Neurospora crassa (wild-type and two morphological mutants), Penicillium claviforme, Rhizoctonia solani and Rhizopus arrhizus also underwent apical bursting when flooded with water or rapidly heated. Schizophyllum commune, several Phytophthora spp., and some morphological mutants of N. crassa were refractory.

The bursting of hyphal tips by flooding colonies with water is not simply an osmotic phenomenon; its temperature coefficient (Q10 1.3 to 2.0) suggests the additional participation of biochemical reaction(s) as a rate-limiting step in the bursting process. Probably, enzymatic degradation and hence weakening of the wall is a prerequisite for bursting. These observations are offered as circumstantial evidence supporting the following conclusions: (i) the growing tips of fungi have a large wall lytic potential; (ii) the release of this activity during growth must be gradual and delicately co-ordinated with wall synthesis; (iii) this balance can be easily disturbed by a wide variety of external stimuli and the ensuing surge of lytic activity results in the violent disintegration of the hyphal apex.

SUMMARY: In four out of five strains of Staphylococcus aureus examined, genes determining fusidic acid resistance were associated with a penicillinase plasmid. In one strain (FAR5), although the linkage was unstable, resistance to fusidic acid was co-transduced with resistance to cadmium ions and penicillinase production. Further evidence for a single plasmid in this strain was obtained by studying the physical nature of the plasmid DNA. The molecular weight of the entire linkage group was about 16 million daltons; the molecular weight of the residual plasmid after loss of fusidic acid resistance was about 15 million.

SUMMARY: Populations of over 400 Epidinium ecaudatum caudatum/ml were maintained for over 18 months in the presence of bacteria, in a potassium phosphate-rich medium under 95% N2 + 5% CO2 with the daily addition of wholemeal flour and dried grass. Polyplastron multivesiculatum was also maintained at a population density of 45 to 70/ml under the same conditions, except that it was necessary to add each day a culture of another protozoon such as Epidinium ecaudatum caudatum, E. ecaudatum tricaudatum or Eudiplodinium maggii to give a population density of approximately 100/ml. The epidinia at least were engulfed by the polyplastron up to 10 being taken up each day; the minimum daily requirement for growth was one epidinium/polyplastron. Polyplastron multivesicutum also grew in the absence of other protozoa on a sodium chloride-rich medium, and if these protozoa were inoculated into the potassium phosphate-rich medium in the presence of epidinia, there was a lag of 3 to 5 days before they began to engulf the epidinia. The effect of other variations in the culture conditions is also described.

SUMMARY: The rumen bacterium Quin’s Oval has been maintained anaerobically in vitro for more than 1 year in liquid culture at 39°C, in the presence of other bacteria, rumen fluid, lactate, n-valerate, isovalerate, DL-α-methylbutyrate, L-cysteine, mannitol and a CO2 gas phase. The maximum population density attained was 8.1 × 106/ml. No growth was obtained in sterile media or in solid media. Growth and glycogen storage occurred when the organisms were incubated with mannitol, glucose, fructose, mannose and sucrose; amino acids, proteins and polysaccharides were not so utilized. The organisms did not survive freezing, but were viable after 2 weeks at 4°C. The morphology as seen in the light microscope and the staining of the organisms is described.

SUMMARY: Growth yields of Azotobacter vinelandii from carbon source and oxygen were reassessed to define more clearly the terms, maintenance and true growth yield.

In oxygen-limited chemostat cultures, the maintenance coefficients, m (mmol glucose/mg bacteria/h) and m 0 (mmol O2/mg bacteria/h) were 8 × 10−4 and 5.5 × 10−3; i.e. 6m ≃ m 0. This relationship between m and m 0 explains the perfect oxidation of carbohydrate (glucose) by maintenance metabolism. Values of the true growth yield, Y G (mg bacteria/mmol glucose) and Y GO (mg bacteria/mmol O2) were 46 and 13; these values were lower than those recorded for other micro-organisms.

In glucose-limited chemostat cultures, fairly high values of m and m 0 were observed and in addition, negative values of Y G and Y GO were obtained. Energy-uncoupled growth could account for these negative values.

SUMMARY: When Mycobacterium smegmatis was in an approximately balanced state of growth on glucose as the sole carbon source, free trehalose turned over at about 3 times the rate of its net formation, while the sugars of acyltrehalose and acylglucose turned over at about 13 and 8 times the rate of their net formation, respectively. Total lipid turned over substantially more slowly than this, while turnover of polysaccharide and of cell residue was slight or non-existent. However, in spite of their high turnover, the acylated sugars did not represent a major pathway of glucose metabolism, because of their low content in the bacteria.

SUMMARY: Mitomycin-C increased the titres of all of nine colicins tested, regardless of whether the colicin factor comprised a sex factor.

SUMMARY: The physiological and general characters of 123 strains of Listeria were examined, and 33 of these were compared, in a computerized numerical analysis, with Erysipelothrix, Streptococcus, Corynebacterium, Microbacterium, Arthrobacter, Jensenia, Brevibacterium, Cellulomonas and Kurthia. It was concluded that Listeria and Erysipelothrix are distinct monospecific genera, not closely related.

On physiological grounds, Listeria bore the nearest resemblance to faecal streptococci, and Erysipelothrix to other streptococci.

SUMMARY: An investigation involving gel-diffusion, haemagglutination and absorption tests has been made to determine whether cross-reactions in gel-diffusion precipitin tests between Listeria monocytogenes, Erysipelothrix rhusiopathiae and Bacillus licheniformis observed in this laboratory were due to the Rantz antigen. It is concluded that they were not.

R factors conferring high-level resistance to trimethoprim and sulphonamides were identified in bacteria causing infections in patients at three London hospitals in 1971 (Fleming, Datta & Grüneberg, 1972). All were members of the W compatability group and came from the Camden area (Datta & Hedges, 1972).