- Volume 60, Issue 2, 1970

SUMMARY: The effect of synthetic and naturally occurring polyamines on bacterial growth was studied. The tetra-amine spermine was the most potent anti-bacterial agent and showed maximal activity at high pH values. The anti-bacterial action of the triamines was dependent upon the number of the primary amino groups in the polyamine molecule and was maximal when it contained a -N(CH2)7N- moiety. Polyamines, in low concentrations, stimulated the incorporation of [14C]uracil into the nucleic acids of growing bacteria, whereas higher concentrations were inhibitory. In contrast the incorporation of [14C]valine into bacterial proteins was inhibited by polyamines, even in low concentrations.

SUMMARY: The physical factors and nitrogen requirements for the growth of the aquatic phycomycete Catenaria anguillulae in liquid shaken cultures from measured zoospore inocula were examined. Growth was determined by measuring mycelial dry weight and rate of titratable acid production. The optimum pH range for growth was pH 8.2 to 8.7. The toxicity of the pH indicators used was assessed. The optimum temperature for growth was 25°. The organism was highly aerobic. Inorganic nitrogen sources were not utilized. When organic nitrogen sources were supplied individually, L-aspartic acid, L-asparagine, L-glutamic acid, L-arginine, DL-citrulline and L-ornithine were utilized. Asparagine was the best single source. When the N sources were supplied as Difco vitamin-free Casamino acids, only lysine, methionine and arginine were utilized during the lag phase. During the more rapid phase of growth, all of the amino acids detected in the Casamino acids were utilized. When the vitamin-free Casamino acids were replaced by an equivalent amino acid mixture, the subsequent decrease in yield was not corrected by adding NaCl, oleic acid or stearic acid. The optimum concentrations of various N sources were determined. The medium finally evolved contained L-asparagine + L-lysine as N sources.

SUMMARY: The spines projecting from the surface of the mature conidia of Cunninghamella elegans are hollow and are more or less circular in cross-section. The scanning electron microscope shows blunt tips and disc-like bases. The bases are partially embedded in shallow depressions in the outer wall of the spore. The spines are readily detached during processing for transmission electron microscopy.

Mature ungerminated conidia have 2-layered walls, and contain several nuclei, many mitochondria, numerous lipid bodies and sparse endoplasmic reticulum.

Shortly after being placed in water or a nutrient solution the conidia swell; irregular-shaped food vacuoles develop and the lipid bodies largely disappear. Germination takes place from 1 to 3 hr afterwards. A layer of material, denser than the original inner spore wall, develops over the germ-tube initial and later extends over the germ tube after emergence, tapering just behind the point of emergence to a thin dense line surrounding the entire spore. Both layers of the original spore wall are ruptured by emergence of the germ tube, apparently mechanically. These observations are relevant to the evolution of conidia.

SUMMARY: Cellulolytic bacteria were counted by the ‘direct’ method; estimated from the number of clearings produced in films of cellulose-containing agar medium inoculated with high dilutions of rumen ingesta and by the ‘indirect’ method; numbers were calculated from ‘total culturable’ counts on films of a non-specific agar medium and from the percentages of bacteria found to be cellulolytic after isolation in pure culture. The two methods yielded similar results.

SUMMARY: On the basis of phenotypic characterization and DNA-DNA homology studies of strains of phytopathogenic Pseudomonas species, it is concluded that P. cepacia is so similar to P. multivorans that the latter name should be regarded as a synonym. On similar grounds, P. alliicola appears to be a synonym of P. marginata. P. caryophylli is a readily distinguishable species. From the DNA-DNA hybridization studies all of these species seem to be related to each other and to the animal pathogens P. pseudomallei and P. mallei.

SUMMARY: Strains of Pseudomonas stutzeri and related denitrifying bacteria were compared in their phenotypic properties and mean deoxyribonucleic acid (DNA) base composition. On the basis of this comparison and of in vitro DNA hybridization experiments, it was concluded that, using practical diagnostic tests, no more than two nomenspecies can be recognized within the group. One, P. stutzeri, was extremely variable in phenotypic characteristics and in DNA base composition; we included in it the strains previously assigned to P. stanieri. The other was a new species, P. mendocina Palleroni, which was more homogeneous in phenotypic characters, and in DNA base composition and homology. The comparative properties of known denitrifying pseudomonads are tabulated.

SUMMARY: When Escherichia coli B was heated at 52° and subsequently incubated at 20° or at 37° in phosphate buffer, there was an increase in the number of viable organisms. No such increase was observed when the treated suspension was incubated at 0°5°. Untreated organisms did not increase in number when incubated in phosphate buffer, suggesting that the increase in viable number of heat-treated organisms was not due to division. The observed increase in number of viable organisms was time-dependent and complete in about 60 min., but could be stopped by exposing the treated organisms to X-ray doses greater than 1°5 krad., before or after the heat treatment. Growing the organisms in the presence of chloramphenicol 100 μg./ml. before heat treatment also blocked the repair mechanism, but this could be reestablished by growth in the absence of chloramphenicol for 30 min. before heat treatment.

SUMMARY: The dry weight of Penicillium chrysogenum starved of an energy source decreased exponentially. The protein, RNA, DNA and endogenous respiration decreased rapidly during the first few hours of starvation and reached about 25% of their original values after 5 days starvation. The carbohydrate content of the mould only decreased after the first 2 days of starvation. About 60% of the carbon lost during autolysis was oxidized to carbon dioxide. Lysis of organelles in individual hyphal compartments occurred synchronously and did not seem to involve autophagy. Autolysis of separate compartments in the same hyphae was not synchronized. Ribosomes were rapidly degraded but membranes were particularly resistant to breakdown. Intra-hyphal hyphae were observed. In the final stages of autolysis the culture consisted largely of empty hyphal walls. A proportion of cytologically normal hyphal compartments were present at all stages, suggesting that maintenance and/or cryptic growth of some hyphae (or compartments) occurred at the expense of others.

SUMMARY: Low doses of penicillin which inhibited division but permitted filament formation in Escherichia coli did not influence the total rate of phospholipid formation but altered the ratio of individual phospholipids to that characteristic of resting organisms: the filaments contained more cardiolipin and less phosphatidyl glycerol than normal exponentially dividing organisms. Addition of penicillinase to growing filaments restored both normal division and the normal phospholipid ratio. Filaments induced by u.v.-irradiation showed similar changes in phospholipid ratio. These findings suggest that phospholipids or their derivatives are directly involved in division.

SUMMARY: Thirty-nine human cutaneous and eight bovine obligate-lipophilic corynebacteria were examined for their fatty acid requirements for growth. Twenty-five saturated and five unsaturated compounds did not support growth. Oleic acid in cis, trans and iso forms supported various degrees of growth. Erucic acid was also utilized but not ricinoleic and nervonic acids. Linoleic acid supported the growth of some strains but linolenic acid did not. These acids were not inhibitory to most strains tested. Three short-chain acids (acetic, lactic, propionic) and glycerol did not potentiate growth of the strains in the presence of oleic acid. In oleic acid broth, palmitic acid which did not support growth alone, stimulated 14 strains and inhibited three others. Strains of Corynebacterium bovis differed from the human strains in their growth response.

SUMMARY: The chromosomal location of the genes for host specificity in Salmonella typhimurium has been investigated by F-mediated conjugation using host specificity mutants isolated previously. It was found that the sites of mutations leading to two distinct phenotypes, r− LTm+ LT and r− LTm− LT, are closely linked to each other and are located near the marker proC.

SUMMARY: Growth of four fungi on a medium of potato tuber extract and glucose was considerably higher than on a defined medium of glucose, asparagine, mineral salts, biotin and thiamine. Modification in turn of the carbon, nitrogen and growth factor components of the defined medium to resemble the extract medium did not indicate that any single component was responsible for growth stimulation; stimulation appeared to be due to the combined effects of all components. A synthetic medium of glucose, citric acid, amino acids, mineral salts and growth factors resembled the extract medium in composition and approached it in the ability to support growth of the test fungi.