bluuebunny/crossref_metadata_2025 huggingface dataset:
Lipids of cell walls of Pseudomonas aeruginosa and Brucella abortus
Authors: Bobo R. A. , Eagon R. G.
Published: February 2010

A survey of the content and composition of lipids from isolated cell walls of Pseudomonas aeruginosa and Brucella abortus was made. The following results are average values from several experiments. The readily extractable lipids made up 15.7% and the firmly bound lipids 8.7% of the dry weight of the cell walls of P. aeruginosa. The readily extractable lipids of B. abortus cell walls accounted for 11.4% and the firmly bound lipids 6.4% of the dry weight of the walls.The readily extractable lipids were further separated into phospholipids, free fatty acids, and neutral lipids. These lipids of P. aeruginosa cell walls contained 44.9% phospholipids and 52.9% free fatty acids and neutral lipids. In B. abortus cell walls the phospholipids accounted for only 22.1% of the free lipids whereas the free fatty acids and neutral lipids made up 76.1%.The phospholipids of P. aeruginosa and B. abortus were shown by thin-layer chromatography to be composed of four and seven components respectively. The bulk of the phospholipids was phosphatidyl ethanolamine and diphosphatidyl glycerol of the cardiolipin type. Lysophosphatidyl ethanolamine was also present in both organisms. The presence of phosphatidyl choline could not be demonstrated conclusively since choline could not be detected in the hydrolytic products of the phospholipids; however, infrared spectra of the total lipids and of the phospholipids of both P. aeruginosa and B. abortus showed absorption bands at 970 cm−1 which are characteristic of phosphatidyl choline.Gas–liquid chromatography of the free fatty acids of P. aeruginosa showed the major portion of these acids to be C16 and C18 saturated and monounsaturated fatty acids. The bulk of the free fatty acids of B. abortus consisted of C18 saturated, monounsaturated, and polyunsaturated (C18:2) together with lesser amounts of C16 saturated and monounsaturated acids. Two components were tentatively identified as C19 cyclopropane and C19:0 fatty acids respectively. Small amounts of both C12 and C14 saturated fatty acids were found in both organisms. No hydroxy fatty acids could be identified in either P. aeruginosa or B. abortus.Calcium and magnesium, determined by atomic absorption spectrophotometry, were associated with all the phospholipid components in both organisms. However, the largest quantities of calcium and magnesium were found in the phospholipid components, phosphatidyl ethanolamine and diphosphatidyl glycerol. Trace amounts of zinc were present in all phospholipid components of the cell walls of both microorganisms. Manganese was not detected.
Microbial growth on mercaptosuccinic acid
Authors: Hall Mark R. , Berk Richard S.
Published: February 2010

Using enrichment culture technics a species of Alcaligenes (M1) was isolated from soil which was able to utilize mercaptosuccinic acid (MS) as a sole source of carbon, sulfur, and energy. Growth on a MS–salts basal medium was not significantly enhanced by single supplements of B-vitamins or by yeast extract. Comparative studies on succinate and MS oxidation by Alcaligenes and Pseudomonas aeruginosa indicated that MS was an inhibitor of succinate oxidation by resting cells of both microorganisms when they were grown in a medium lacking mercaptosuccinic acid such as a succinate–salts basal. However, when M1 was grown on MS, it was able to oxidize both succinate and MS, thereby indicating that the MS oxidase system was inducible. In addition, the MS oxidase system in cell-free extracts of M1 was relatively insensitive to 10–30 μmoles of malonate, whereas the succinoxidase system was inhibited 66% by 30 μmoles of the inhibitor. Cell-free extracts of succinate-grown cells of P. aeruginosa were unable to oxidize MS, indicating that the inactivity of resting cells was not due to a permease problem. Investigation of the metabolic fate of the sulfur moiety of MS by growing cells of M1 indicated that all of the available sulfur was liberated as inorganic sulfate, while no free sulfide was detected. Thiosulfate sulfurtransferase (rhodanese) was detected in extracts from cells grown both with and without mercaptosuccinic acid. However, growth in the MS medium enhanced the production of rhodanese approximately 40%. In addition, thiosulfate oxidase activity was also detected in resting cells and cell-free extracts prepared from MS-grown cells, but not from cells grown without mercaptosuccinic acid.
11α-Hydroxylation of steroids by spores of Aspergillus ochraceus
Authors: Sehgal S. N. , Singh Kartar , Vezina Claude
Published: February 2010

Spores of A. ochraceus were used to transform a variety of steroids into their 11α-hydroxy derivatives. Physicochemical data of some new 11α-hydroxy derivatives are presented. Specificity of A. ochraceus in relation to steroid transformations is discussed.
Immunofluorescence in the study of viruses in tissue culture. II. Development of an immunofluorescent cell assay for influenza (A/PR8) virus
Authors: Sattar S. A. , Westwood J. C. N.
Published: February 2010

A rapid and sensitive assay method has been developed for influenza (A/PR8) virus in abortively infected African green monkey kidney cells. Using immunofluorescence, primarily infected cells could be scored within 12–13 hours after virus inoculation. It has been demonstrated that this technique gives reproducible results and exhibits a direct relationship between virus concentration and the number of fluorescent cells. The assay system has been shown to be more sensitive than the quantitative hemadsorption technique.
Some patterns of B vitamin requirements among neritic marine bacteria
Authors: Burkholder Paul R. , Lewis Seymour
Published: February 2010

Twenty-four different patterns of single and multiple requirements for various B vitamins were demonstrated for 665 cultures of marine bacteria grown in a basal synthetic seawater medium enriched with phosphate, vitamin-free casamino acids, dextrose, and succinate. Among 114 thiamine-requiring isolates, 55 were unable to make the pyrimidine moiety, 19 required thiazole, 13 needed both thiazole and the pyrimidine moiety, while 27 organisms required thiamine or thiamine pyrophosphate for growth. Among 142 biotin requirers, 22 had to be supplied with biotin, 60 could use either biotin or biocytin, 54 were able to respond to either biotin, biocytin, or desthiobiotin. Only six cultures could not use biocytin, and required either biotin or desthiobiotin. Various responses of vitamin B12 requiring cultures indicated special types of specificity for cyanocobalamin and analogues of this vitamin. Computer-sorting at the 0.66 similarity coefficient breaking point arranged a group of 104 isolates into eight clusters. The isolates having biotin or thiamine requirements, single or in combination with other vitamin needs, appeared to be randomly scattered through the eight clusters.
The effects of mutation and nucleic acid base analogues on the sensitivity of E. coli to partial dehydration
Authors: Webb S. J. , Walker Janet L.
Published: February 2010

Investigations have been carried out on the effect of mutation and the incorporation of base analogues into the deoxyribonucleic acid (DNA) of cells on their resistance to dehydration. Auxotrophic mutant cells have been found to possess the same sensitivity or a greater sensitivity than the parent prototrophic organism. This suggests that mutant cells, previously found in populations surviving periods of desiccation, occurred as a result of induced mutation and not the concentration of mutants existing in the cell population before its dehydration. In addition, the incorporation of nucleic base analogues into the DNA of cells has been found to alter their sensitivity to dehydration. With some analogues, the sensitivity of cells is increased and with others it is decreased. Also, the presence of nucleic acid base analogues in the DNA of cells markedly inhibits the ability of myo-inositol to protect cells against dehydration damage. These results suggest that the dehydration of cells is mutagenic and inositol is able to preserve the integrity of desiccated cells by combining with specific areas of normal DNA.
The influence of cell water content on the inactivation of RNA by partial desiccation and ultraviolet light
Authors: Webb S. J. , Walker Janet L.
Published: February 2010

The influence of the water content of cells of Escherichia coli K38 and Escherichia coli B on the inactivation of F2 phage RNA and β-galactosidase mRNA by partial desiccation and 2537 Å ultraviolet light (uv.) has been studied. Both types of RNA were found to resist desiccation and their inactivation by ultraviolet to require much larger doses than the destruction of the colony-forming ability of cells. The ability of non-induced cells to produce β-galactosidase was destroyed by desiccation and irradiation more easily in non-induced cells than in preinduced cells. The inactivation of RNA was found to occur more readily when the cells contained from 10 to 15 g H2O/100 g of cell solids than when the cells contained less water. Damage by desiccation and irradiation, however, was partially prevented by i-inositol.It is concluded that damage to existing cell RNA either by ultraviolet or desiccation is not involved in the loss of cell viability and that cell death occurs as a result of damage to the mechanism by which mRNA is manufactured.
Influence of nitrogen source on formation of chloramphenicol in cultures of Streptomyces sp. 3022a
Authors: Westlake D. W. S. , Sala F. , McGrath R. , Vining L. C.
Published: February 2010

The rate of growth and chloramphenicol production of Streptomyces sp. 3022a can be controlled by varying the nitrogen source used in the medium. Sources such as peptone and nitrate support rapid growth but the high initial rate of antibiotic production was not sustained. Nitrogen sources which resulted in slow, controlled growth supported the highest yields of chloramphenicol. DL-Serine was the most suitable nitrogen source to use in this synthetic medium as good yields of chloramphenicol were obtained within a reasonable incubation period, e.g. 7 days.The substitution of part of the nitrogen supplied as DL-serine as nitrate (e.g. up to 2% of the total nitrogen supplied) decreased the fermentation time required without affecting the total amount of chloramphenicol produced. Nitrate at higher concentrations inhibited both chloramphenicol and mycelial production whereas the complete elimination of DL-serine from the medium restored mycelial production but not chloramphenicol production. Studies with 15N-nitrate showed that the nitro group of chloramphenicol does not originate from a biological nitration reaction but rather that both nitrogen atoms are derived from a common pool.The low dilution of radioactivity obtained from 14C-glycerol as compared with serine-1,3-14C indicates that serine does not have a special role as a precursor of chloramphenicol. Rather its value lies in its ability to control the growth rate of Streptomyces sp. 3022a, maintaining physiological conditions suitable for the formation of chloramphenicol.
Formation of endospores in Verticillium albo-atrum (R. & B.)
Authors: Aube Claude , Pelletier Gilles
Published: February 2010

A morphological study of a hyaline strain of Verticillium albo-atrum (R. & B.) has revealed that spores are produced intrahyphally. Some implications of this finding are briefly discussed.
Some unusual mutants of a locus related to the am locus in Neurospora
Authors: Kapoor M. , Smith D. W.
Published: February 2010

A mutation in a gene in Neurospora crassa leading to a semicolonial growth pattern and a deficiency of NADP-specific glutamate dehydrogenase is reported. The NAD-specific enzyme is not affected. The mutants (referred to as am-morphs) do not show any nutritional requirement nor is the growth pattern altered by addition of supplements in the medium. Addition of L-alanine, L-glutamate, and other α-amino acids to the medium does not result in an appreciable increase in specific activity of the NAD-specific glutamate dehydrogenase. This is due to the inability of amino acids to induce the NAD-specific enzyme, a phenomenon known to occur in the familiar am mutants. A spontaneous revertant of one of these mutants shows a mycelial morphology together with a normal glutamate dehydrogenase.The behavior of am-morphs is discussed in relation to other amination-deficient, mycelial mutants.
Influence of cold-shock on the endogenous metabolism of Pseudomonas aeruginosa
Authors: MacKelvie R. M. , Gronlund Audrey F. , Campbell J. J. R.
Published: February 2010

Late stationary phase cultures of Pseudomonas aeruginosa were found to be very susceptible to cold-shock during harvesting. Washing in cold buffer caused a sudden decrease in the number of viable cells and a persistent release of intracellular enzymes. The phenomenon was characterized by an increased oxygen uptake and an initial absence of extracellular ammonia during the respiration of washed cell suspensions. The presence of oxidizable substrates in the supernatant fluid accounted for these observations. A partial inhibition of the release of intracellular materials was afforded by the addition of magnesium ions to the washing and suspending buffer. There was an increased sensitivity of cells to cold-shock with age.
Survival and intracellular changes of Pseudomonas aeruginosa during prolonged starvation
Authors: MacKelvie R. M. , Campbell J. J. R. , Gronlund Audrey F.
Published: February 2010

The viability of suspensions of Pseudomonas aeruginosa, prepared from 48-h cultures, grown in either a nitrogen-limited or carbon-limited medium, decreased 25% during 48-h of endogenous respiration, whereas the viable numbers of 48-h cells harvested from a complete medium increased 57% during the early stages of endogenous respiration and remained constant thereafter. In all endogenously respiring cell suspensions, ribonucleic acid and protein decreased by similar amounts and deoxyribonucleic acid increased. Glucosamine was not found to decrease to a significant degree during starvation. Constitutive enzymes and (or) the cofactors involved in the oxidation of glucose were found to diminish with progressive starvation. Starvation severely depleted the ribosome complement of the cells; however, the starved cells were able to synthesize a permease for α-ketoglutarate. The addition of an exogenous substrate brought about the reincorporation of endogenously liberated ammonia and of 260 mμ absorbing material with a concurrent synthesis of 50S ribosomes.
Lytic phages produced by DNA-infected mycobacteria
Authors: Capet-Antonini F. , Mankiewicz E.
Published: February 2010

DNA extracted from two mycobacteriophages have been shown to be infective for three different strains of mycobacteria during their multiplication in liquid medium. The infection resulted in a modification of the phage genome. A study of the plaque morphology, host range, heat resistance, efficiency of plating, and neutralization rate showed significant differences between the donor phage and the phage progeny.
Mitomycin C induction of a temperate phage in Pseudomonas aeruginosa
Authors: Yamamoto T. , Chow C. T.
Published: February 2010

After addition of mitomycin C to Pseudomonas aeruginosa strain MAC-264 cells, DNA synthesis stops but resumes again after 45 min. This resumption in DNA synthesis is due to the induction of a temperate phage. Early after induction, both RNA and protein syntheses continue but later on little or no net synthesis of these macromolecules occurs. Cell lysis occurs at 90 to 105 min after addition of mitomycin C. Analysis of the lysates indicates that a DNA phage with an icosahedral head about 55 mμ in diameter with a short wedge-shaped tail is produced. This phage [Formula: see text] has a buoyant density of 1.468 g/ml in CsCl. The guanine + cytosine content of the phage DNA determined by its buoyant density in CsCl is 46% compared to 68% for the host DNA.Some phage tail-like structures which have a buoyant density of 1.305 g/ml in CsCl are also induced at the same time.
Spheroplasts of enteropathogenic Escherichia coli. I. Biological characteristics
Authors: Diena B. , Wallace R. , Greenberg L.
Published: February 2010

The properties of glycine-induced spheroplasts of six pathogenic serotypes of E. coli were investigated. Fimbriae and flagella appeared to be only partially synthesized as was the somatic O antigen. Cytopathogenicity of these spheroplasts for tissue culture was reduced and the infection of the monolayers was retarded as compared with the normal bacillary forms. Sensitivity to phage was almost completely lost, suggesting that glycine had either interfered with the synthesis of phage receptors or had altered the mucopeptide layerwhich is the substrate for phage enzymes. Alternatively, the phage may become a prophage inside the spheroplast with the loss of virulence.
Spheroplasts of enteropathogenic Escherichia coli. II. Immunogenicity of spheroplast vaccines
Authors: Diena B. , Wallace R. , Benns G. , Greenberg L.
Published: February 2010

Soluble vaccines of enteropathogenic E. coli were prepared by growing six serotypes in a semi-synthetic medium with 1.5% glycine and lysing them with Pronase. The active mouse protection and ligated rabbit gut tests were used to assess immunogenicity. Good protection (90–100%) was obtained with monovalent vaccine against the homologous serotype and limited (0–90%) protection against heterologous serotypes. A dose of 1.6 mg of 10 times concentrated polyvalent vaccine offered 71–100% protection in mice against challenge by all serotypes. These lysed spheroplast vaccines were considerably less toxic than killed whole cell vaccine.
Thermal injury and death in an obligately psychrophilic yeast, Candida nivalis
Authors: Nash C. H. , Sinclair N. A.
Published: February 2010

Exposure of the obligately psychrophilic yeast, Candida nivalis, to temperatures greater than 20 C, its maximal growth temperature, results in a rapid loss in viability. Furthermore, many of the cells surviving heat treatment are metabolically injured. Injured cells are unable to develop on a glucose – mineral salts – vitamins medium but are able to develop on a complex tryptone – glucose – yeast extract medium. Recovery of injured cells on the complex medium is due to the yeast extract component. Addition of cysteine, reduced glutathione, or thioglycollate to the minimal medium also enhances recovery of heat-injured cells.Additional evidence of heat-induced damage is the release of various cellular components into the suspending menstruum. These include inorganic phosphate, amino acids or short polypeptides, and nucleotide monophosphate. Leakage of these materials into the heating menstruum is not due to cell lysis. The correlation between leakage and loss in viability suggests that membrane damage is at least one factor which determines the low maximal growth temperature of C. nivalis.
Nutritional requirements of mutants of Escherichia coli resistant to gamma irradiation
Authors: Robern Haskel , Thatcher F. S.
Published: February 2010

The nutritional requirements of three mutants resistant to γ irradiation were investigated. The mutants were derived from a wild type strain of Escherichia coli and were arbitrarily designated in order of resistance as 1γ < 6γ < 12γ.Studies of growth of these strains in basal medium (mineral salts – glucose), peptone medium, and a complete chemically defined (CCD) medium, showed that the wild type and 1γ mutant grew in all media, but the 1γ mutant exhibited a prolonged lag phase in basal medium. The 6γ and 12γ mutants did not grow in basal medium but grew in peptone medium and in CCD medium (mineral salts, glucose, amino acids, purines, and pyrimidines) after a lag of several hours. None of the amino acids, purines, and pyrimidines were required for growth by the 1γ mutant, but leucine, methionine, and valine were stimulatory. The 6γ mutant required leucine, methionine, and proline, while threonine and valine were marked stimulants. The 12γ mutant required leucine, methionine, proline, valine, arginine, cysteine, histidine, tryptophan, and uracil or cytosine. Threonine was a strong stimulant for this strain. Thus, the nutritional requirements of the mutants resistant to γ irradiation increased with increased resistance to γ irradiation, and compounds which stimulated growth of a mutant with lower resistance to irradiation became essential for the mutants exhibiting a higher resistance.
Aspergillus fumigatus Fresenius isolated from ornithogenic soil collected at Hallett Station, Antarctica
Authors: Wicklow Donald T.
Published: February 2010

Aspergillus fumigatus was isolated with high frequency from samples of ornithogenic soil collected from an Adélie penguin rookery at Hallett Station, Antarctica. While A. fumigatus has been well documented as the principal incitant of aspergillosis among penguins in captivity, this represents the first report of its presence in antarctic materials. Aspergillus flavus and Aspergillus ustus were also found in the Hallett samples. In a comparable number of soil and guano samples from isolated Adélie rookeries on Foyn Island and Possession Island, these fungi were not encountered. It is suggested that their presence at Hallett Station may be the result of human contamination. A brief consideration of epidemiological implications is given.
Antigenic analysis of Shigella sonnei by gel diffusion technics
Authors: Martin W. J. , Mock W. E. , Ewing W. H.
Published: February 2010

The technics of immunogel diffusion as applied to soluble antigen concentrates of both smooth (S or DI) and rough (R or DII) forms of Shigella sonnei were studied. By using these procedures and using both homologous and heterologous antigens and antisera as well as specifically absorbed antisera, data were obtained that provided additional information which helped to clarify S–R (DI–DII) variations and the O and K antigens of S. sonnei. The same technics also were utilized to show the antigenic relationship between DI forms of S. sonnei and the C27 strain of Aeromonas shigelloides. The results of these studies suggested that O and possibly K antigens were shared between these two bacteria. Moreover, the association between the respective DII and R forms of S. sonnei and Shigella boydii 6 was confirmed and suggested the possibility of a degraded O antigen relationship. The applicability of gel diffusion methods by visual characterization of the antigenic interrelationships within members of the family Enterobacteriaceae was noted.
A reversible inhibition of the germination of bacterial spores
Authors: Parker M. S. , Bradley T. J.
Published: February 2010

The germination of Bacillus subtilis spores in stationary aerobic culture is inhibited by p-chloro-m-cresol. Spores inhibited in this way can be recovered and induced to germinate by the addition to stabilized cultures of the non-ionic surfactant, polysorbate (Tween) 80. In this way the stabilization of the germination process by the inhibitor may be reversed after periods of stabilization of up to 21 hours. The inhibitor may interfere with an enzymatic lytic activity responsible for germination initiation. A denaturation process is not indicated.
The action of antibiotics on heteroglucan production by strains of Azotobacteriaceae
Authors: Portoles A. , Lopez R. , Hidalgo A.
Published: February 2010

Qualitative and quantitative variations in the production of heteroglucans by three different species of Azotobacteriaceae in the presence of certain antibiotics (penicillin, tetracycline, and polymyxin B) were investigated. The authors found that these substances were produced at a slower rate and in smaller amounts when antibiotics were present. However, study by infrared spectrometry, chromatography, and colorimetry revealed that the most striking changes were qualitative and were caused by the hexuronic acids.
Isolation and purification of the D(–)β-hydroxybutyric dehydrogenase of Azotobacter vinelandii
Authors: Jurtshuk Peter , Manning S. , Barrera C. R.
Published: February 2010

It has been possible to isolate and purify the D(–)β-hydroxybutyric dehydrogenase from cell-free extracts of Azotobacter vinelandii. Standardized resting cell suspensions were disrupted by sonic oscillation, and purification of the enzyme was achieved by use of protamine sulfate, ammonium sulfate, and hydroxyapatite or by direct use of a Svensson-Porath preparatory column electrophoretic unit. The D(–)β-hydroxybutyric dehydrogenase was found to be a classical, soluble, NAD+-dependent dehydrogenase and neither bound nor associated with any intracellular membranous structure. The highest specific activity achieved was 17 μmoles NAD+ reduced per minute per milligram protein at 37°. Two unusual features were noted with this dehydrogenase: (a) loss of activity occurred when the enzyme was dialyzed in the absence of metal ion; and (b) marked stability was observed when the enzyme was exposed to alkaline pH even at 40 °C for hours.
The uptake of tritiated thymidine by human amnion cells: a correlation with cell structure
Authors: Hrushovetz S. B. , Wilt J. C. , Lee E. S. C.
Published: February 2010

It was found that less than 1% of amnion cells, either as membrane biopsies, as trypsinized cell suspensions, or grown as monolayers on glass incorporated tritiated thymidine during a 1-hour incubation period; this was in contrast to HeLa cells in which over 30% of the cell population incorporated tritiated thymidine. Continuous labelling with tritiated thymidine for a 24-hour period with or without colchicine failed to increase the percentage of labelled amnion cells, while a minimum of 80% of the HeLa cells became labelled. Less than 0.1% of the amnion cells were in mitosis, compared to 4% for HeLa cells. Incubation with colchicine for 24 hours failed to increase the percentage of mitotic figures of the amnion cells. It is concluded that most of the primary amnion cells are in the non-proliferative phase of the cell cycle.
A rapid test for an antifungal substance produced by a wood-inhabiting fungus in culture
Authors: Stillwell M. A. , Hodgson W. A.
Published: February 2010

Inhibition of indirect germination of sporangia of the potato late blight fungus was used to detect the presence and measure the relative potency of antifungal substances produced in vitro by two wood-inhibiting fungi. This technique is simple to perform and the results are obtained in less than 2 hours.
Antibiotic resistance of glycine-resistant variants of Staphylococcus aureus
Authors: Parisi Joseph T. , Suling William J.
Published: February 2010

Glycine-resistant variants of Staphylococcus aureus were obtained by successive cultivation of parent strains in increasing concentrations of glycine, and the minimal inhibitory concentrations of glycine of the parents and variants were determined. Although it has been reported that growth in glycine or certain antibiotics causes the accumulation of nucleotides involved in cell wall synthesis, a lack of cross resistance of the variants to some of these antibiotics was observed.
Metabolic changes in biotin-deficient Aspergillus nidulans
Authors: Rao K. K. , Modi V. V.
Published: February 2010

Biotin deficiency has been found to result in greatly diminished ability to synthesize fatty acid, causing decrease in the lipid content of the mold. This decrease is accompanied by considerable increase in protein content of the mat.There is 30% reduction in lipid content of the mitochondria of the biotin-deficient molds. This should have resulted in the loss of mitochondrial integrity affecting the general metabolism of A. nidulans. On the other hand, under these conditions the mat weight of the mold increases.
X-Ray analysis of hyphal and sclerotial walls of Sclerotium rolfsii Sacc.
Authors: Chet I. , Henis Y.
Published: February 2010

Hyphal and sclerotial walls of Sclerotium S. rolfsii show X-ray diffraction patterns corresponding to chitin, and to β-(1 → 3) glucan. Diffraction patterns of melanin-like pigment, extracted from sclerotial walls, are absent from the hyphal walls. The absence of pustulan and cellulose from S. rolfsii walls is confirmed.
Nutritional studies of a flagellated protozoan Hexamita inflata from the Canadian oyster, Crassostrea virginica
Authors: Khouw B. T. , McCurdy Jr. H. D.
Published: February 2010

The physical and nutritional requirements for growth of Hexamita inflata have been studied in axenic cultures. The flagellate was capable of growing over a wide range of temperature (5 °C to 25 °C), of hydrogen ion concentration (pH 4.5 to 8.5), and of salinity (3 to 28‰); and required a reducing or anaerobic environment. The requirement of an egg-yolk suspension for growth was partially satisfied by unsaturated fatty acids. Attempts to replace the peptone by mixtures of amino acids were not successful. A simple medium containing a vitamin mixture, linoleic acid, glucose, cysteine, peptone, and salt has been formulated.
Ultrastructure and sites of tetranitro-blue tetrazolium reduction of Lactobacillus casei
Authors: Brown Joseph P. , Edwards Mercedes R. , VanDemark Paul J.
Published: February 2010

Cells of two strains of Lactobacillus casei incubated for 2–10 h in the presence of tetranitro-blue tetrazolium (TNBT) and mannitol were studied in electron micrographs of ultrathin sections. The reduction product tetranitro-blue diformazan (TNBF) was found to be predominantly associated with the plasma membrane and its derivatives. Untreated cells (normal control), as well as cells incubated with mannitol in absence of TNBT (dye control), or with omission of mannitol (substrate control) displayed ultrastructural characteristics, in general, similar to those previously reported for other Gram-positive bacilli, particularly Lactobacillus species.
Respiration of Lactobacillus casei
Authors: Brown J. P. , VanDemark P. J.
Published: February 2010

Although Lactobacillus casei is generally considered to be "indifferent" to oxygen, several strains exhibited considerable respiratory activity with a number of substrates related to carbohydrate catabolism. In many cases this respiratory ability enables the organism to utilize energy sources that would be unavailable under anaerobic conditions. The chief features of respiration of L. casei strain 103 were fairly representative of those examined. [Formula: see text] (N) values of this strain on glucose ranged from 75 to 200 and with mannitol from 250 to 500. This respiration was insensitive to 1.7 mM KCN and the rate of oxygen consumption was independent of oxygen concentration from ca. 500 μM to ca. 6 μM with an apparent Ks(O2) of 3 μM. Enzymatic studies indicated that this respiration was mediated by flavin-linked reduced pyridine nucleotide oxidase(s) and peroxidase(s) and did not involve benzo- or naphtho-quinones. No H2O2 accumulation occurred with glucose or mannitol as substrate. Growth yield coefficients of 21.7 and 24.4 with glucose and mannitol respectively as energy sources under aerobic growth conditions indicate that electron flow through these flavin respiratory enzymes was not coupled to any additional energy yielding.
An infrared study of the influence of growth media and myo-inositol on structural changes in DNA induced by dehydration and ultraviolet light
Authors: Webb S. J. , Dumasia M. D.
Published: February 2010

The infrared spectra of films of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and synthetic polynucleotides have been studied under varying degrees of relative humidity (R.H.) in the presence and absence of myo-inositol. In addition the effect of 2537 Å light (ultraviolet) on the hydration of DNA has been investigated. As other researchers have shown, when the R.H. is lowered shifts in the P=O and C=O absorption frequencies occur. These shifts seem to be associated with the removal of approximately 12 molecules of water/nucleotide and all are prevented by the presence of 2 molecules of inositol/nucleotide during desiccation. The irradiation of DNA at 75% R.H. with ultraviolet also produces spectral shifts which appear to arise as a result of bound water molecules moving from P=O and C=O groups.The response of bacterial DNA to desiccation appears to depend on the medium in which the cells are grown. The DNA from cells grown in a minimal salts medium is less hydrated at a given R.H. level than the DNA from cells grown in an enriched medium. This loss of water-adsorbing sites is considered to be due to a physiological replacement of water on the DNA of cells grown on minimal salt medium by amino acids or proteins. RNA and polynucleotides are less hydrated than DNA, which is assumed to be due to their lack of an ordered double helical structure. Of the synthetic polynucleotides poly-I was found to most closely resemble the behavior of DNA. The ability of inositol to prevent spectral shifts in DNA caused by desiccation and irradiation tends to substantiate the suggestion that it preserves the biological integrity of cells and viruses during stress by combining with DNA.
A proteolytic pseudomonad from skin lesions of rainbow trout (Salmo gairdnerii). II. Some properties of the proteinase
Authors: Li M. F. , Jordan Carol
Published: February 2010

An extracellular proteinase from a pseudomonad pathogenic to rainbow trout was purified 33-fold by ammonium sulfate fractionation, DEAE-cellulose column chromatography, and Sephadex G 75 gel filtration. The purified enzyme was active over a wide pH range, from pH 5.0 to 10.0. Heating at 98 °C for 1 h did not completely inactivate the enzyme. Its observed temperature optimum was 45 °C. Michaelis–Menten constants were found to be 0.625% for casein and 0.263% for rainbow trout muscle albumin. Activation energies calculated for these substrates were 8.1 kcal and 11.4 kcal per mole, respectively. The involvement of bivalent cations and free sulfhydryl groups in the enzymatic activity was demonstrated by the inhibition caused by metal-complexing agents and p-chloromercuribenzoate, respectively.
The bentonite flocculation test in the serology of tuberculosis. I. Purification of BCG antigens
Authors: Diena B. B. , Yugi H. , Wallace R. , Carriere J. , Greenberg L.
Published: February 2010

Fractionation of unheated bacillary extract of BCG has yielded a carbohydrate fraction which sensitizes bentonite to react with circulating antibodies to M. tuberculosis in human sera. This fraction does not contain tuberculin-like protein material in appreciable amount, but is rather a mixture of carbohydrates, varying in molecular size and all possessing bentonite-sensitizing activity.
Action of ethylenediaminetetraacetic acid, tris(hydroxymethyl)aminomethane, and lysozyme on cell walls of Pseudomonas aeruginosa
Authors: Cox Jr. S. T. , Eagon R. G.
Published: February 2010

Incubation of isolated cell walls of Pseudomonas aeruginosa with tris(hydroxymethyl)aminomethane (Tris), ethylenediaminetetraacetic acid (EDTA), and lysozyme, either singly or in combinations, results in partial solubilization of the cell walls.When cell walls were incubated with a combination of Tris and EDTA, approximately 30% of the total cell wall and 32% of the lipopolysaccharide fraction were solubilized. The following percentages of the individual cell wall constituents were solubilized: protein, 19%; carbohydrate, 35%; lipid, 5%; ash, 54%; and, phosphorus 23%. When lysozyme was included with Tris and EDTA, approximately 36% of the total cell wall and 86% of the lipopolysaccharide fraction were solubilized. Solubilization of the individual cell wall constituents was similarly increased.Phospholipids, which make up 7–8% of the intact cell wall of P. aeruginosa, were not released by incubation of the cell walls with these agents. Fatty acids in addition to those found in the lipopolysaccharide, however, were detected in the solubilized cell wall materials.Incubation systems composed of Tris, of EDTA, and of Tris and lysozyme solubilized cell walls to a lesser extent than incubation systems of Tris and EDTA, and of Tris, EDTA, and lysozyme. Incubation of cell walls in water, furthermore, was effective in solubilizing approximately 8% of the cell walls. Muramic acid containing materials were solubilized only in the presence of lysozyme.Materials liberated from cell walls which were incubated in systems containing EDTA exhibited single symmetrical Schlieren peaks characterized by uncorrected sedimentation constants of approximately 7 S, suggesting the release of homogenous subunits from the cell walls.Intra- and inter-molecular cross-linking by divalent cations via phosphate groups contained in lipoprotein and lipopolysaccharide components of the cell wall of P. aeruginosa is proposed.
Rhizopterin biosynthesis in Staphylococcus epidermidis
Authors: Jones Larry P. , Williams F. D.
Published: February 2010

The biosynthetic pathway from 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine (hydroxymethyldihydropteridine) to 10-formyldihydropteroic acid (dihydrorhizopterin), as found in cell-free extracts of Staphylococcus epidermidis grown in a glucose–casein hydrolysate medium, is described. In the first of at least three reactions, hydroxymethyldihydropteridine enzymatically reacts with adenosine triphosphate (ATP) in the presence of MgCl2 to form the pyrophosphate ester of this dihydropteridine and adenosine monophosphate. Cell-free enzyme preparations couple the dihydropteridine pyrophosphate with p-aminobenzoic acid (PABA) to form a phosphate containing dihydropteroic acid derivative. Enzymatic incubation of dihydropteroic acid phosphate with one-carbon donor compounds and adenosine diphosphate results in the formation of dihydrorhizopterin and ATP. Evidence is presented that the phosphorylated dihydropteroic acid compound can only be formed from the pyrophosphate ester of hydroxymethyldihydropteridine and not from dihydropteroic acid and ATP. Dihydrorhizopterin biosynthesis proceeds only from the dihydropteroic acid phosphate derivative and could not be shown to occur from 5-formyltetrahydrofolic acid. Cell-free extracts prepared from cells grown in brain heart infusion broth do not form any rhizopterin-like compounds, but form dihydropteroic acid from the phosphorylated dihydropteroic acid.
Thymineless death of Staphylococcus aureus and formation of its alpha toxin
Authors: Mathieu L. G. , Repentigny J. de , Turgeon S. , Sonea S.
Published: February 2010

We have observed that alpha toxin is apparently not synthesized during the thymineless death of a thymine-requiring mutant of Staphylococcus aureus Wood 46 strain, i.e., when no growth occurs. When the thymineless mutant is suspended in a thymine-free medium supplied with all the other growth requirements, and incubated at 37 °C, there is a lag phase of about 2 hours before the onset of the logarithmic decrease in viable units (108–105 cells/ml) in the following 6 hours of starvation. In addition, even if the bacterial cells lose their ability to form deoxyribonucleic acid (DNA), they still synthesize other macromolecules like ribonucleic acid, proteins, and some antigens precipitating with commercial antitoxin, but not with antialpha toxin. During the killing phase, the cell population becomes highly heterogeneous. Our results suggest that the molecular integrity and (or) normal replication of DNA are necessary for the formation of staphylococcal alpha toxin.
Effects of toluene on microflora and hydrolysis of urea in a black spruce humus
Authors: Roberge M. R.
Published: February 2010

The value of toluene as an antiseptic in determining the activity of urease in soil was studied in the surface organic horizon of a black spruce (Picea mariana Mill.) forest soil. Toluene was added in various amounts to layers of the humus suspended in water or in phosphate buffer, or sterilized by radiation, and incubated for various periods of time, followed by 8-h treatments with urea. Viable bacteria and fungi were detected by the dilution plate technique and the products of urea hydrolysis were determined by extraction and distillation. By increasing the amount of toluene or the time of contact of toluene with the humus, bacteria and fungi were reduced in number but not completely eliminated. The presence of urea resulted in a larger decrease of bacteria and fungi. With an increase in the amount of toluene, but not in the time of contact of toluene, a decrease was observed in urea hydrolysis. Some of the decrease was due to the inhibition of urease by toluene, and possibly some to the absorption of the products of urea hydrolysis and (or) to a lower production of urease by the surviving microorganisms. The last two possibilities render questionable the use of toluene in the determination of urease activity in soils.
Metabolism of p- and m-xylene by species of Pseudomonas
Authors: Davis R. S. , Hossler F. E. , Stone R. W.
Published: February 2010

Species of Pseudomonas isolated from soil could utilize m- or p-xylene as the sole carbon source. The respective toluic acids of the xylenes were isolated from growth media and from cells suspended in buffer. Cells grown on either hydrocarbon were capable of "meta" type cleavage of catechol and the methylcatechols. A compound whose properties were consistent with the structure of 2-hydroxy-5-methylmuconic semialdehyde was produced when cell-free extracts of p-xylene-grown cells were confronted with 4-methylcatechol. This muconic semialdehyde was present in the growth medium of p-xylene-grown cells and in buffer suspensions of these cells confronted with p-xylene. Paraxylene-grown cells oxidized p-chlorotoluene and 4-chloro-catechol to a compound with a spectrum similar to those of "meta" cleavage products. Chemical isolations and manometric data are consistent with a pathway for the oxidative metabolism of p-xylene which includes p-methylbenzyl alcohol, p-tolualdehyde, p-toluic acid, 4-methylcatechol, and 2-hydroxy-5-methylmuconic semialdehyde.
A method for isolating leptospires from natural surface waters
Authors: Braun John L. , Diesch Stanley L. , McCulloch William F.
Published: February 2010

A method for isolation of leptospirae from natural surface waters with initial inoculation under field conditions is described. Leptospirae were isolated from 19 of 51 water samples obtained from five Iowa streams. The problem of coincidental contamination was successfully resolved by using Millipore filtration schema and serum containing liquid and semisolid media.
The fine structure of Arthrobacter pascens and the development of mesosomes during the growth cycle
Authors: Stevenson I. L.
Published: February 2010

Actively growing cells of Arthrobacter pascens were sectioned and examined by electron microscopy. The cell wall, plasma membrane, mesosomes, and mode of division are typical of Gram-positive organisms. Mature mesosomes appear as a series of uniform, convoluted tubules (280–325 Å in diameter) bounded by a single unit membrane. The development of the mesosomes was followed throughout the growth cycle by thin section and negative staining techniques. Coccoid stationary phase cells (48 hours) contained a large number of simple membranous inclusions. On transfer to fresh media the cells undergo a 4-hour predivisional lag during which time the cells enlarge to pleomorphic rods. During this period only one to three developing mesosomes are noted per cell. By 4 to 5 hours when active division has been initiated, only mature vesiculotubular mesosomes are present, primarily at or near the site of septum formation. Rudimentary membrane inclusions begin to reappear at the end of active growth (7 to 8 hours) corresponding to the time of medium limitation. During the reversion of the pleomorphic rods to the coccoid stage, mature mesosomes disappear and only rudimentary profiles remain. The fact that the period required for the development of mesosomes coincides with the predivisional lag period of A. pascens suggests a definite role of these membranous intracellular organelles in the division process.
Effect of various nitrogen sources on growth of Sclerotinia
Authors: Willis C. B.
Published: February 2010

A wide range in growth responses was obtained by two isolates each of Sclerotinia trifoliorum Erikss. and S. sclerotiorum (Lib.) d By. in stationary culture in a synthetic liquid medium containing a number of nitrogen sources representing both organic and inorganic forms. Good sources of nitrogen were casein hydrolysate, L-proline, DL-asparagine, L-arginine, L-glutamic acid, L-aspartic acid, L-histidine, L-alanine, ammonium chloride, ammonium nitrate, L-tryptophan, ammonium sulfate, and DL-phenylalanine. Poor nitrogen sources included potassium nitrite, sodium nitrite, DL-lysine, L-valine, L-cysteine, DL-threonine, and DL-methionine. An additional eight sources were intermediate in the amount of growth supported. Growth by the S. trifoliorum isolates on the ammonium nitrogen sources was significantly greater than on the nitrate sources. No such difference was observed for the S. sclerotiorum isolates. DL-Phenylalanine ranked much lower and L-glutamic acid and calcium nitrate much higher as nitrogen sources for the S. sclerotiorum isolates than for S. trifoliorum isolates. Significant differences between the isolates of each species were observed on a number of nitrogen sources.
Effects of biotin on glutamate production and fatty acid composition in Bacillus cereus 14B22
Authors: Hubbard Jerry S. , Hall Alan N.
Published: February 2010

Bacillus cereus 14B22 exhibits a biochemical regulation by biotin. In glucose–salts or citrate–salts media, limiting amounts of biotin restrict cellular synthesis and induce synthesis of high yields of extracellular L-glutamic acid. With nonlimiting levels of biotin, abundant cellular synthesis occurs without the concomitant accumulation of glutamate. The biotin status of cells was not reflected in experiments with cell-free extracts. Citrate was converted to glutamate at comparable rates by extracts of biotin-sufficient and biotin-deficient cells. The biotin requirement for growth can be replaced with Tween 80 or with a mixture of Tween 40 and oleic acid. The yields of glutamate given by cultures of these "fatty acid-grown cells" were intermediate between those obtained with biotin-deficient and biotin-sufficient cells. Biotin deficiency also altered the fatty acid composition of the cell membrane. The proportion of straight-chain to branched-chain fatty acids is significantly smaller in low-biotin cells than in high-biotin cells. These changes did not affect cellular permeability to glutamate. Variations in the morphology of B. cereus 14B22 as influenced by biotin and the fatty acid composition of the medium are described.
The structure of the diatom Thalassiosira fluviatilis
Authors: Dweltz N. E. , Colvin J. Ross
Published: February 2010

The structure of the diatom, Thalassiosira fluviatilis, was investigated by a study with the electron microscope of thin sections of cells fixed by OsO4, KMnO4, and glutaraldehyde. The weakly siliceous cell wall is composed of a thin sheet perforated by holes about 250 Å in diameter and arranged in a roughly orthogonal manner. At the ends of the barrel-shaped cell are marginal and central pores composed of an outer cylinder (0.25 μ in diameter and 1 μ long) arranged coaxially with an inner, smaller, shorter cylinder. The thin, perforated sheet (valve) which connects these pores is reinforced from place to place by radial or transverse ribs.Mitochondria, nuclei, chloroplasts, and pyrenoids have the same general structure and appearance as those in other diatoms. Small vacuoles are numerous but it is not known whether they are filled with gas or solution. The cells often show aggregates of an amorphous material which does not stain like lipid or protein but which may be the residue of a gelatinous, reserve carbohydrate (chrysolaminarin).