bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on antibiotic biosynthesis by protoplasts and resting cells of Streptomyces echinatus. Part II. Effect of chromophore precursors
Authors: Gauvreau D. , Swift I. E. , Waring M. J.
Published: May 2010

Washed cell and protoplast suspensions from Streptomyces echinatus A8331, which produces the quinoxaline antibiotic echinomycin, have been used to study the effects of analogues of the natural chromophore upon antibiotic biosynthesis. Addition of quinoline-2-carboxylic acid caused a decrease in the labelling of echinomycin from L-[methyl-14C]methionine and an increase in labelled chloroform-extractable material. Quinoxaline-2-carboxylic acid increased the incorporation of radioactivity into both fractions. Thieno[3,2-b]pyridine-5-carboxylic acid, 6-methylquinoline-2-carboxylic acid, and quinoline-2-carboxylic acid (also to a lesser extent 7-chloroquinoxaline-2-carboxylic acid) increased markedly the incorporation of radioactivity into chloroform-extractable material and virtually abolished echinomycin synthesis. Autoradiographs of extracts from suspensions supplemented with the latter four analogues revealed bis-substituted metabolites not found in unsupplemented cultures. When protoplast suspensions were incubated with L-[U-14C]serine, L-[U-14C]valine, or DL-[benzene ring-U-14C]tryptophan, quinoline-2-carboxylic acid, thieno[3,2-b]pyridine-5-carboxylic acid, and 6-methylquinoline-2-carboxylic acid directed the synthesis of antibiotically active bis derivatives at the expense of echinomycin. When analogues of quinoxaline-2-carboxylic acid previously found unsuitable for incorporation by growing cultures were tested in protoplast suspensions, only isoquinoline-3-carboxylic acid caused a large increase in the incorporation of radioactivity from L-[methyl-14C]methionine into chloroform-extractable material. With DL-[benzene ring-U-14C]tryptophan as the radiolabel, benzotriazoline-2-acetic acid and 6-bromoquinoxaline-2-carboxylic acid as well as isoquinoline-3-carboxylic acid sharply reduced the labelling of echinomycin.
Sporulation-dependent phagelike particles in inclusion-forming Bacillus species
Authors: Tam Anthony , Fitz-James Philip
Published: May 2010

Phagelike particles, which have been observed in sporulated cells of Bacillus medusa, were found to appear at about late stage II in all supspecies of Bacillus thuringiensis toxic to mosquito larvae. All phagelike particles were similar in size and shape and when purified possessed capsid proteins of similar molecular weights and immune reaction. The synthesis of the major capsid protein occurred at the same time as complete phagelike particles were detected by electron microscopy. The production of phagelike particles was not essential for sporulation.
Plasmids associated with a phagelike particle and with a satellite inclusion in Bacillus thuringiensis ssp. israelensis
Authors: Tam Anthony , Fitz-James Philip
Published: May 2010

Variants of Bacillus thuringiensis ssp. israelensis were isolated using a 42 °C plasmid curing method. Those that were missing the large toxic crystalline inclusion still possessed in their sporulated cells a small inclusion similar to the satellite inclusion of the wild type. These crystal-minus but satellite-positive variants, like the wild type, produced sporulation-dependent phagelike particles; variants lacking both the crystal and the satellite did not. These latter strains lacked both a 75 and a 68 megadalton plasmid present in the wild type. However, a crystal-positive, satellite-minus strain possessing the 75 but lacking the 68 megadalton plasmid produced the phagelike particles. Examination of recipient strains that were initially devoid of crystal, satellite, and plasmids revealed the satellite and phagelike producing characteristics could have been cotransformed with the 68 megadalton plasmid. Likewise the toxic crystal and phagelike particle producing characters could have been cotransformed into a recipient which had acquired the 75 megadalton plasmids already known to be associated with the synthesis of the crystal inclusion. Thus the gene coding for the satellite inclusion appears to reside in the 68 megadalton plasmid, while that coding for the phagelike particle can reside in either the 68 or 75 megadalton plasmid.
Mode of cell growth of Malassezia (Pityrosporum) as revealed by using plasma membrane configurations as natural markers
Authors: Takeo K. , Nakai E.
Published: May 2010

The mode of cell growth of Malassezia was studied by freeze–fracture using the plasma membrane configurations of this organism as natural markers. The plasma membrane of the mature cell bodies of M. pachydermatis had a ring swelling, and on each side of the ring, one set of straight and spiral grooves and circumvallate bulgings. The cell always divided at the ring swelling (M. pachydermatis) or depression (M. furfur), soon followed by budding there. A new set of similar configurations formed on the bud. In all the 12 strains of Malassezia studied, the spiral grooves in the mother and bud parts were both left-handed but opposite in the direction of elongation. By comparing distances between the spiral grooves in short and long buds and in mothers, the bud tip was suggested as the major, and adjacent regions as the minor, sites of wall growth. Some characterizations of the plasma membrane invaginations, especially in relation to the mode of cell growth, were also described.
Effect of iron concentration on toxin production in Campylobacter jejuni and Campylobacter coli
Authors: McCardell Barbara A. , Madden Joseph M. , Stanfield John T.
Published: May 2010

The effect of iron concentrations in culture media on supernatant yields of Campylobacter cytotonic toxin (CCT) was studied. Of the 118 Campylobacter spp. strains surveyed, 78.8% produced toxin in brucella broth or in casamino acids – yeast extract (CYE) broth. When the iron concentration of CYE was increased from 0.44 μg/mL (7.9 μM) to 0.65 μg/mL (11.6 μM) by the addition of ferric chloride, 94.9% of the strains were positive for toxin in a ganglioside GM1 based, enzyme-linked immunosorbent assay, using antibody to affinity-purified CCT. The addition of iron as ferrous sulfate was less effective. When four toxin-positive strains were grown in a deferrated medium of conalbumin-treated CYE with 0.04–0.08 μg iron/mL (0.72–1.43 μM), two of the culture supernatants became negative (absorbance at 410 nm, < 0.1 and < 10 ng CCT/mL), and two produced about 90% less CCT but were still classified as positive (absorbance, ≥ 0.1 and ≥ 10 ng CCT/mL). It was therefore concluded that the production of CCT by Campylobacter spp. is influenced by iron concentration.
Antigenic relationship of N2-fixing Pseudomonas strain H8 to various known cultures and rice rhizosphere isolates studied by indirect enzyme-linked immunosorbent assay (ELISA)
Authors: Barraquio W. L. , Ladha J. K. , Yao H. Q. , Watanabe I.
Published: May 2010

The serological relationship of several, mainly Gram-negative, bacteria including type cultures and previously isolated rhizosphere bacteria, to Pseudomonas sp. strain H8, a N2-fixing rhizosphere isolate from Maahas soil, was examined by indirect enzyme-linked immunosorbent assay. None cross-reacted significantly with H8 antibody except some of those rhizosphere bacteria previously found cross-reactive by fluorescent antibody test. Several new rhizosphere isolates from wetland rice grown in various fields showed significant immunoreactivity, and most of the reactive bacteria reduced acetylene. However, the cultural characteristics and acetylene reduction activity of most of these isolates were different from those of H8. None of the rhizosphere isolates from dryland rice cross-reacted. In a pot experiment, bacterial cultures similar to H8 were found only in Maahas soil, but none reacted with antibodies against strains H8 and KLH76 (another N2-fixing pseudomonad from rice root). Other isolates showing reaction with these antibodies were, however, neither culturally similar to these strains nor N2 fixing. The data suggest that Pseudomonas sp. H8 is not distributed widely in soils other than that from which it was originally isolated.
Superoxide dismutase and catalase in Frankia
Authors: Steele D. Bernie , Stowers Mark D.
Published: May 2010

Superoxide dismutase (SOD) and catalase (CAT) are important enzymes in the protection of cell components from oxidation via superoxide free radicals [Formula: see text] and hydrogen peroxide (H2O2). SOD and CAT activities in Frankia, under non-nitrogen fixing conditions, are among the highest reported in prokaryotes. A sixfold increase in SOD activity (2150 units/mg of protein) and a twofold increase in CAT activity (413 units/mg of protein) was seen in cultures derepressed for nitrogen fixation compared with ammonium-grown cultures. Frankia possesses a manganese-containing SOD (MnSOD) when grown with ammonium as the nitrogen source. An additional SOD isozyme containing iron (FeSOD) was detected in cell extracts when grown with dinitrogen. Methyl viologen induced higher activity of the MnSOD in ammonium-grown cultures but failed to induce the FeSOD. During derepression of nitrogenase activity, the simultaneous induction of SOD and CAT was detected. The presence of a new iron-containing SOD under nitrogen-fixing conditions could provide an additional mechanism for protection from O2 toxicity.
Denitrification by Cytophaga johnsonae strains and by a gliding bacterium able to reduce nitrous oxide in the presence of acetylene and sulfide
Authors: Adkins Anne M. , Knowles Roger
Published: May 2010

A gliding bacterium (Is-11), isolated for its ability to reduce nitrous oxide (N2O) in the presence of acetylene (C2H2) and sulfide, was able to use nitrate (NO3−), nitrite (NO2−), and N2O as terminal electron acceptors for growth. Similarly, of five strains of Cytophaga johnsonae examined, two were capable of complete denitrification. Two strains were unable to reduce nitrate and N2O, respectively, and the remaining strain lacked both nitrate and N2O reductases. However, in this strain the N2O reductase was induced by the presence of nitrite, but not nitrate. Acetylene inhibited N2O reduction but did not affect the reduction of nitrite or nitrate in all of the gliding bacteria tested. Sulfide temporarily inhibited all of the nitrogen oxide reductases. It did not relieve the C2H2 inhibition of N2O reduction in the C. johnsonae strains when tested under the same conditions under which C2H2 inhibition is relieved in Is-11.
In vitro requirements for formate dehydrogenase activity from Desulfovibrio
Authors: Riederer-Henderson Mary Ann , Peck Jr. Harry D.
Published: May 2010

In Desulfovibrio the protein(s) involved in formate dehydrogenase activity have not been identified or characterized. In situ assays in polyacrylamide gels demonstrated that formate dehydrogenase from either D. gigas or D. vulgaris catalyzed the direct reduction of either methylene blue or benzyl viologen in the presence of formate. Thus, the same protein was active with either electron acceptor. Although the enzyme could be stored in air without irreversible inactivation by O2, activity with either dye was stimulated by the addition of thiols to the assay mixture. In the absence of formate the thiols served as a substrate for the in situ reduction of methylene blue or benzyl viologen by the enzyme. Ammonium sulfate fractionation revealed the presence of a fraction which selectively stimulated activity with either benzyl viologen or cytochrome c3 as the electron acceptor. The stimulating fraction was nondialyzable, heat labile, and unstable upon storage. The fraction from either species could stimulate the formate dehydrogenase activity of the other species. The protein may be of physiological signficance as it increased when the cells were grown on formate, and it stimulated the formate hydrogenlyase system with cytochrome c3 as the electron carrier.
Properties of formate dehydrogenase from Desulfovibrio gigas
Authors: Riederer-Henderson Mary Ann , Peck Jr. Harry D.
Published: May 2010

The formate dehydrogenase from extracts of Desulfovibrio gigas was partially purified to a specific activity of 5600 nmol CO2 ∙ min−1 ∙ mg protein−1. Uniquely for a formate dehydrogenase from anaerobes, the enzyme was stable when stored aerobically. Nevertheless, thiols were required in the assay mixture for enzymatic activity. If the enzyme first catalyzed the transfer of electrons from thiols to benzyl viologen (a diaphorase activity), then formate was oxidized rapidly without a lag period. The enzyme had a molecular weight of approximately 240 000, a pH optimum of 7.5–8.0, and a temperature optimum of 56 °C. Activity with cytochrome c3 (molecular radius (Mr) = 13 000) was about twice that with ferredoxin or flavodoxin as the electron acceptor. These results suggest that the formate dehydrogenase from D. gigas can be activated by transferring electrons from thiols to an electron acceptor and uses cytochrome c3 as the natural electron carrier for the oxidation of formate.
Effect of lipopolysaccharide mutations and temperature on plasmid transformation efficiency in Pseudomonas aeruginosa
Authors: Berry Denise , Kropinski Andrew M.
Published: May 2010

We have isolated, and characterized electrophoretically, two new lipopolysaccharide-defective (rough) mutants of Pseudomonas aeruginosa strain PAO. These strains, AK1401 and AK1414, together with two previously characterized isolates, AK1012 and AK1282, were used as recipients in transformation experiments with plasmid pR01614 DNA. The roughest mutant, AK1282, was not transformable, while the transformation efficiency of AK1012, and to a lesser extent the wild-type strain, was dependent upon the growth temperature. The two new isolates which are less rough than AK1012 were transformed at a frequency equivalent to that of the wild type-strain.
Antibacterial activity of BCG-induced, interferon-containing sera
Authors: Moulton R. G. , Gerner G. D.
Published: May 2010

Sera from mice which have been vaccinated with BCG and challenged with old tuberculin contain gamma interferon. These same sera also express antibacterial activity. Using Staphylococcus aureus we demonstrated that its growth was inhibited at dilutions of sera as high as 1:320. A 4% concentration of sera reduced the growth rate of the S. aureus from 1.6 to 0.6 doubling times per hour. The activity was stable at 56 °C but destroyed by 80 °C. It was nondialysable and destroyed by acid conditions (pH 2.0) and by the proteolytic enzymes trypsin and chymotrypsin. Antibodies to gamma interferon neutralized the antiviral activity but not the antibacterial activity. Mitogen-induced and virus-induced interferons did not have activity. We subsequently demonstrated that the factor could be induced in mice using BCG without the secondary old tuberculin challenge. No gamma interferon was found in the sera of mice given BCG without old tuberculin. These findings indicate that the antibacterial activity of these sera is not dependant on the presence of gamma interferon. We will continue to work to characterize and identify the antibacterial component in these sera.
Bacterial succession during biodegradation of the kelp Alaria esculenta (L.) Greville
Authors: Hollohan Brendan T. , Dabinett Patrick E. , Gow John A.
Published: May 2010

In northern latitudes large quantities of kelp can be dislodged by ice scouring during spring and early summer. Quantities of kelp are then available to enter the detrital food chain. Bacterial succession, on decaying fronds of the brown macroalga Alaria esculenta, was investigated. There was a loss of approximately 70% of the algal mass during late spring and summer. During this time Vibrio dominated the heterotrophic bacterial population. Species of marine Pseudomonas comprised about 10–30% of the population, depending upon the occasion of isolation. By using numerical taxonomy it was shown that the strains of Vibrio formed distinct and separate clusters according to the occasion on which they were isolated. Among Pseudomonas strains a more gradual change was observed, but by the time of the final isolation, the Pseudomonas strains were different from those isolated at the beginning of the study. The results of characterization tests showed that strains from all clusters were suited to growth on substrates which are components of brown algae and that a succession of bacterial species, of more than one genus and family, occurred during the decay process.
C-390 as sole selective agent for isolation of Pseudomonas aeruginosa from hospital waste water
Authors: Havelaar A. H. , During M.
Published: May 2010

Pseudomonas aeruginosa was recovered (in numbers ranging from 102 to 105 colony-forming units per millilitre) from heavily contaminated hospital waste water when grown at 41.5 °C on a differential medium agar containing 9-chloro-9-(4-diethylaminophenyl)-10-phenylacridan (C-390) at a final concentration of 30 μg/mL. The medium appeared to be highly selective for P. aeruginosa with 95–100% of all colonies isolated from four different hospital waste waters being identified as P. aeruginosa. Many strains of P. aeruginosa isolated from hospital waste waters failed to hydrolyse casein when grown on skim milk agar and this medium appeared to restrict pigment production to only pyoverdin (detectable only under ultraviolet light). However, most strains were capable of casein hydrolysis when grown on a modified skim milk medium.
Patterns of extension growth of the fission yeast, Schizosaccharomyces pombe
Authors: Miyata H. , Miyata M. , Johnson Byron F.
Published: May 2010

The growth of sausage-shaped cells of the fission yeast, Schizosaccharomyces pombe (strain NCYC 132), was followed in the second or third cycle by time-lapse photomicrography. Experimental cells were harvested from glucose-limited (0.2% glucose EMM3) chemostat culture (dilution rate, 0.125/h) and were plated onto a slide with EMM3 agar (2% glucose). By observing their extension patterns, we found some rules of extension growth. Thus, (1) all sibs with walls newly formed in the previous cycle, whose progenitor cells grew at the old end (followed Mitchison's rule), grow at the old end (also follow Mitchison's rule). (2) Sibs with old walls whose progenitor cell followed Mitchison's rule behave in one of three ways: (i) growth at the old end (follow Mitchison's rule); (ii) growth at the new end (violate Mitchison's rule); or (iii) growth at both ends (bipolar). (3) Both sibs whose progenitor grew at both ends (bipolar) always grow at the old end (follow Mitchison's rule).
Opsonic activity of antisera to ribosomal vaccine fractions with live and formalinized Pseudomonas aeruginosa
Authors: Lieberman Michael M. , Allen Robert C.
Published: May 2010

The opsonic capacity of antisera to Pseudomonas aeruginosa ribosomal vaccine fractions was determined by a chemiluminescent technique. Antiserum to a vaccine fraction ("peak A") containing lipopolysaccharide (antiserum A), and antiserum to a vaccine fraction ("peak B"), which did not contain detectable amounts of lipopolysaccharide (antiserum B), were used to opsonify live or formalin-treated bacteria. Polymorphonuclear leukocytes were then stimulated by the opsonified bacteria in the presence of the chemiluminigenic probe, luminol, resulting in the observed chemiluminescence. The data obtained indicated that the antisera had comparable opsonic activity with live (untreated) bacteria. However, antiserum B had far less opsonic activity than did antiserum A when formalinized bacteria were used. Owing to the effects of formaldehyde on protein, these results were interpreted as evidence to suggest that the opsonic activities of the two antisera are dependent on different antigens on the bacterial cell surface. Antiserum A activity is probably dependent on lipopolysaccharide to a great extent, whereas antiserum B activity is most likely dependent primarily on a protein(s).
Factors relating to the aerotolerance of Spirillum volutans
Authors: Padgett Penelope J. , Krieg Noel R.
Published: May 2010

A variant of the microaerophile Spirillum volutans capable of growth under an air atmosphere (21% oxygen) was obtained by sequential selection and stabilization of colonies able to grow on a casein hydrolysate – succinate – potassium metabisulfite medium under an atmosphere of 14, 16, 18, 20, and finally 21% O2. A small amount of bisulfite (0.0025%) was still required, however, for aerobic growth. Both the variant and the wild type lacked catalase activity, and they had the same levels of superoxide dismutase activity. However, the mutant possessed 13 times more donor: hydrogen-peroxide oxidoreductase (peroxidase) activity (0.008 IU) than the wild type (0.0006 IU). An aerotolerant mutant was also isolated in one step by treatment with the mutagenic agent ethyl methane sulfonate, followed by incubation under 21% O2; it was found to possess approximately three times the peroxidase activity of the wild type. This mutant lacked catalase activity and the level of superoxide dismutase activity it contained was comparable with the wild type.
Molybdenum nutrition of isolates of four Aspergillus species
Authors: Agarwala S. C. , Chatterjee C. , Nautiyal N. , Sharma C. P.
Published: May 2010

The molybdenum requirement for growth and conidial formation by Aspergillus flavus, A. terreus, and A. sulphureus was found to be 0.2 ppb, which was one-fifth that of an A. niger isolate. Molybdenum deficiency depressed growth, conidial formation, dry weight, soluble protein, and the specific activities of nitrate reductase, succinic dehydrogenase, and aconitase in all the isolates of Aspergillus studied, but the specific activities of catalase and peroxidase were depressed only in isolates of A. niger, A. terreus, and A. flavus. Also, molybdenum deficiency stimulated the specific activities of acid phosphatase and ribonuclease in the A. flavus isolate, although the specific activities of these enzymes decreased in other isolates. Eighteen hours after the addition of molybdenum (5 ppb) to molybdenum-deficient (0.02 ppb) cultures of A. niger, the specific activities of catalase, peroxidase and succinic dehydrogenase were restored in the absence of cycloheximide, while the specific activity of nitrate reductase was recovered even in the presence of the inhibitor. There was no effect on the specific activities of aconitase and acid phosphatase following the addition of molybdenum to molybdenum-deficient cultures of A. niger.
Characterization of microorganisms involved in accelerated biodegradation of metalaxyl and metolachlor in soils
Authors: Bailey Ana Maria , Coffey Michael D.
Published: May 2010

The metabolism of the chemically related fungicide metalaxyl and the herbicide metolachlor was studied in soils and in liquid culture. Experiments with [14C]metalaxyl demonstrated that it was readily metabolized in a soil (E9) with a history of fungicide treatment, but not in a control soil. The respective half-lives of metalaxyl and metolachlor in the E9 soil were 14 and 56 days. Fourteen soil microorganisms were isolated, identified, and tested for their relative ability to degrade [14C]metalaxyl and [14C]metolachlor. With single microorganisms, breakdown of metalaxyl ranged from 36–52% after 25 days, and up to 75% with mixtures of either fungi or bacteria. Four products of metalaxyl metabolism, isolated by two-dimensional thin-layer chromatography, were tested for their antifungal activity using Phytophthora boehmeriae as a sensitive bioassay organism. All four breakdown products were inactive at concentrations up to 2.5 μg/mL, contrasting with an effective concentration for 50% inhibition of growth of P. boehmeriae for metalaxyl of 0.02 μg/mL. Rates of breakdown of metolachlor ranged from 4 to 86% with different microorganisms. Products of metolachlor breakdown possessed no herbicidal activity at concentrations up to 10 μg/mL. Cell-free extracts of four species of soil bacteria were also active in metalaxyl degradation.
Purification of a third distinct xylanase from the xylanolytic system of Trichoderma harzianum
Authors: Wong Ken K. Y. , Tan Larry U. L. , Saddler John N. , Yaguchi Makoto
Published: May 2010

Three of the xylanases produced by Trichoderma harzianum E58 passed through a polysulfone membrane with molecular mass cut-off of 10 000 daltons, even though their molecular mass had been estimated to be 20 000, 22 000, and 29 000 daltons. The 22 000 dalton xylanase was purified to homogeneity from a preparation containing a mixture of 22 000 and 20 000 dalton xylanase using a combination of hydrophobic column chromatography and chromatofocusing. This enzyme has a pI of 8.5, a specific activity of 0.28 U/mg, a temperature optimum between 45 and 50 °C, a pH optimum between 4.5 and 5.0, and the ability to cleave xylotriose. It differs from the other two xylanases by having a lower pI, a lower specific activity, and a lower thermal tolerance. All three xylanases are highly specific for xylan hydrolysis and they do not cleave xylobiose or release arabinose substituents from arabinoxylan. Their amino acid compositions suggest that they are three distinct gene products. The three enzymes are major components of the xylanolytic system of T. harzianum, which consists of at least two other xylanases and two β-xylosidases which are responsible for the release of arabinose substituents and the hydrolysis of xylobiose.
Restriction endonuclease activities in the legionellae
Authors: Chen Grace C. C. , Brown Arnold , Lema Michael W.
Published: May 2010

Fifteen legionellae isolates were studied for the presence of restriction endonucleases. At least three different specificities were found in nine of these isolates. One particular activity was present in two groups of isolates isolated from widely separated geographic areas.
Physicochemical roles of soluble metal cations in the outer membrane of Escherichia coli K-12
Authors: Ferris F. G. , Beveridge T. J.
Published: May 2010

Atomic absorption spectroscopy of isolated native and EDTA-modified (lipopolysaccharide-depleted) outer membrane revealed trace amounts of potassium, manganese, and iron (1.0–7.0 nmol/mg dry weight outer membrane). Sodium, magnesium, and calcium were approximately one order of magnitude more plentiful, but EDTA-modified outer membrane was deficient in calcium. When metal-binding assays were conducted to find the binding capacity of native and EDTA-modified outer membrane, potassium bound poorly compared with sodium. However, there was no difference in the binding of these ions between the OM preparations. In contrast, reduced amounts of magnesium, calcium, manganese, and iron III bound to the EDTA-modified OM. Partitioning of intact cells in a biphasic dextran–polyethyleneglycol system indicated that the reduced lipopolysaccharide content of the EDTA-modified outer membrane increased the hydrophobicity of the cell surface. Exposure of control and EDTA-treated cells to divalent metal salt solutions before phase partitioning also increased cell surface hydrophobicity. Freeze-etching showed that sodium ions had no effect on the membrane fractures observed in control cells, but with EDTA-treated cells, this cation increased the occurrence of small outer membrane fractures (plateaus) which are characteristic of EDTA treatment. Both magnesium and manganese increased the frequency of outer membrane cleavage in control cells, whereas calcium did not. In contrast, all three divalent metallic ions increased the frequency and extent of cleavage in the outer membrane of EDTA-treated cells.
Structure, partial elemental composition, and size of Thiopedia rosea cells and platelets
Authors: Scherrer René , Shull Vivion E.
Published: May 2010

The phototrophic purple sulfur bacterium Thiopedia rosea forms multicellular, gas-vacuolate, regular, flat aggregates (platelets, sheets) held together by slime. Platelets found in eutrophic water consisted of slime (85% of the total wet volume) and 16 cells, while the gas-filled vacuole occupied 44% of the volume of a single wet cell. Individual platelet cells contained central spindle-shaped gas vesicles (which together constitute the cell's gas vacuole), intracytoplasmic membrane vesicles (chromatophores), and peripheral sulfur globules. Cells were surrounded by a Gram-negative type cell envelope and were connected to neighboring cells of the same platelet by mostly unstructured slime. Cells contained detectable amounts of magnesium, phosphorus, sulfur, and potassium as determined by wavelength-dispersive X-ray microanalysis. The large size and relatively low slime density of the platelet, as well as the flat shape, could greatly decrease platelet sedimentation and so stabilize the position of T. rosea within its water column.
Properties of a solubilized replicase isolated from corn infected with maize dwarf mosaic virus
Authors: Donofrio J. C. , Kuchta J. , Moore R. , Kaczmarczyk W.
Published: May 2010

An RNA-dependent RNA polymerase (replicase) activity which catalyzes the polymerization of ribonucleotides into an acid-insoluble product has been isolated and solubilized from the leaves of maize dwarf mosaic virus infected maize. Glycerol gradient sedimentation of the replicase indicates a molecular mass of approximately 160 000 daltons. The majority of replicase activity resides in the 30 000 × g pellet. The Mg2+ optimum for the viral-associated replicase was determined to be 2.8 mM. The solubilized enzyme fraction exhibits characteristics similar to those reported for viral-induced replicase. The replicase requires all four ribonucleotides for maximum activity, is insensitive to added DNase, α-amanitin, rifampin, and exotoxin from Bacillus thuringiensis, is sensitive to added RNase, and is stimulated by added RNA. There was an increase in the incorporation of [3H]UMP when actinomycin D was omitted from the reaction mixture. Various species of RNA were effective as template. The enzyme showed approximately 30% activity when no exogenous template was added. Labeled nucleotides were incorporated into RNA at a linear rate by the replicase. The reaction products include a double-stranded partially RNase-resistant RNA. Sodium diethyldithiocarbamate stimulates template-dependent and to a lesser extent template-independent activity.
Stability of viruses in waste water sludge eluates
Authors: Hurst Christon J. , Goyke Tamara
Published: May 2010

The survival of indigenous enteric viruses in samples of unconcentrated and concentrated waste water sludge eluates, which had been prepared using a combination beef extract elution – organic flocculation concentration procedure, was studied at 2, 23, and −70 °C. Changes of virus titer occurring in the samples were followed during an 84-day observation period, with rates of change then calculated by least-squares regression. Virus survival in both types of eluates was statistically dependent (p ≤ 0.05) upon storage temperature. Based upon the observed rates of inactivation the average times which would be required for a 90% decrease (one log10 unit) in virus titer for unconcentrated eluates are 27 days at 23 °C, 198 days at 2 °C, and 375 days at −70 °C. The calculated average times required for a 90% decrease in virus titer for concentrated eluates are 22 days at 23 °C, 132 days at 2 °C, and 246 days at −70 °C. In both types of eluates the rates of virus inactivation at 2 °C were statistically different from those observed at 23 °C, but not different from those observed at −70 °C. The three study temperatures were selected to approximate holding of samples in an air-conditioned room, fluid on wet ice (H2O), and frozen on dry ice (CO2).
Copper and cobalt alter the cell wall composition of Cunninghamella blakesleeana
Authors: Venkateswerlu G. , Stotzky G.
Published: May 2010

Cunninghamella blakesleeana was highly sensitive to Cu and Co on a medium containing NaNO3 as the sole nitrogen source. The nitrate reductive pathway was altered by Cu and Co, and [Formula: see text] accumulated in the medium. Under conditions of Cu toxicity, the mycelium and the cell walls acquired a blue color, and most of the Cu was located in the cell walls, which differed in several aspects from cell walls derived from Co-containing or control cultures. At half-maximal growth inhibition by Cu (2.5 μg/mL or 39.3 μM) or Co (3.5 μg/mL or 59.4 μM), the mycelia contained 1.5 μg Cu or 1.0 μg Co/mg dry tissue, respectively, but the isolated cell walls contained 33.5 μg Cu or 1.8 μg Co/mg dry cell wall. The phosphorous content of mycelia from Co-containing cultures was the same as that from control cultures, whereas that of mycelia from Cu-containing cultures contained 36% less. However, the phosphorous content of the cell walls from mycelia cultured in the presence of Cu or Co was two- and three-fold higher, respectively, than that of cell walls from control cultures. The cell walls of Cu-containing cultures contained significantly less hexosamine than the control cell walls, and chitin and chitosan were present in equal quantities. The cell walls of Co-containing cultures had the same amount of hexosamine as the control cell walls, but 88% of the hexosamine was present as chitosan and bound very little Co. The control cell walls contained approximately 60% chitosan. The cell walls of Cu-containing cultures also contained less alkali-soluble neutral sugar, but more protein, than did the walls from the control or Co-containing cultures. Only the protein of the cell walls of Cu-containing cultures contained hydroxyproline, which is usually absent in the cell walls of fungi and may have been involved in the binding of Cu and in the acquisition of the blue color. The protein of the cell walls from Co-containing cultures was abnormally high in citrulline. Chitinase not only had a greater affinity for the cell walls of Cu-containing cultures, but these were more easily hydrolyzed by the enzyme than the cell walls from Co-containing and control cultures. Melanin was not responsible for the differential rates of hydrolysis by chitinase. The cell walls from control cultures bound more DNA than did the walls from Cu- and Co-containing cultures.
An ultrastructural examination of Penicillium urticae during the transition to antibiotic biosynthesis
Authors: Scott Richard E. , Costerton J. W. , Gaucher G. Maurice
Published: May 2010

The ultrastructure of Penicillium urticae mycelium was compared at various stages of submerged growth to examine changes associated with the onset of antibiotic biosynthesis. Penicillium urticae was shown to be a normal eukaryotic, septate, filamentous fungus with a variety of subcellular components. Younger mycelia possessed a denser cytoplasm which gave way to a more granular and vacuolated cytoplasm as the organism made the transition into antibiotic biosynthesis. An increase in the thickness, and perhaps the structural complexity, of the cell wall also occurred over the transition. There was evidence of a glycocalyx surrounding the hyphae. Discrete granules, termed peripheral particles, appeared and increased in number over the transition. Their biochemical content and possible involvement in patulin production was tested by examining P. urticae after growth in media of different composition, and by examining the ultrastructure of a patulin minus mutant, P3. The significance of these observations in relation to patulin production is discussed.
Cytotoxic factors toward neuroblastoma cells in trypomastigotes of Trypanosoma cruzi
Authors: Asahi Hiroko , Kawabata Masato , Moribayashi Atsuko , Okumura Hideo
Published: May 2010

Homogenates of trypomastigotes of Trypanosoma cruzi (T.c) exhibited low-potency cytotoxic activity toward neuroblastoma cells. The cytotoxic activity was markedly decreased after preservation for 1 week, even at −20 °C. Trypsin and pronase E were shown to effectively enhance or restore the cytotoxic activity of T.c by producing some alteration in T.c, depending on concentrations of and treatment time with the enzymes. The cytotoxic factors were insoluble in saline and found in the chloroform extracts of a T.c homogenate. Analysis by thin-layer chromatography showed that the cytotoxic activity of T.c was found in the free fatty acids and lysophospholipids fractions. Of the free fatty acids present in T.c, eicosatetraenoic (20 : 4) and octadecadienoic (18:2) acids were the most cytotoxic. It was assumed that as much as 27.2% (w/w) of the total lipids of T.c consists of free fatty acids, and 1 mg of protein of the T.c homogenate contains 96 μg of free fatty acids. The abundant free fatty acids appear to account for the cytotoxic activity of the T.c homogenate, although they occurred in T.c under weakly active condition.
Recovery of Mycobacterium avium after treatment with chemical decontaminants
Authors: Jaramillo Victor L. , McCarthy Charlotte M.
Published: May 2010

Cell suspensions of a pathogenic strain of Mycobacterium avium, serovar 1, were tested for susceptibility to chemical disinfectants that are frequently used for decontamination of environmental samples. Kinetic data were obtained by determining the viability at 15-min intervals during 60 min of exposure at room temperature with aeration. After 60 min exposure to a combination of 0.094% ZephiranR, and 10% trisodium phosphate, only 0.3% of the initial number of colony-forming units survived. Survival after 60 min treatment with 2% sodium hydroxide, 1% sodium hydroxide, or 0.04% hexadecylpyridinium chloride was 20, 46, and 57%, respectively. To assess the practical applications, the same agents were employed to extract M. avium that had been seeded into soil. Recovery of more than 25% of the initial number of colony-forming units was achieved with any of the treatments. Several combinations of chloramphenicol and antifungal drugs were tested for inhibition of soil microbiota that survived the decontamination procedures.
Pyridine nucleotide metabolism by extracts derived from Haemophilus parasuis and H. pleuropneumoniae
Authors: O'Reilly T. , Niven D. F.
Published: May 2010

A variety of biologically important pyridine nucleotides and precursors were examined for their capacities to serve as substrates for the synthesis of NAD by cell fractions derived from Haemophilus parasuis and H. pleuropneumoniae. Of the compounds tested, only NMN and nicotinamide riboside were converted to NAD. These reactions required ATP as co-substrate, and fractions from both organisms could also catalyze the ATP-dependent synthesis of NADP from NAD. In the absence of ATP, and depending on the pyridine compound under study, NAD, NMN, nicotinamide riboside, and also nicotinamide, were detected as products of catabolisra. It is concluded that these haemophili possess either three-membered pyridine nucleotide cycles or two-membered cycles with synthetic branches originating with nicotinamide riboside. It is also possible that the pyridine nucleotide cycles of both organisms have nonrecycling branches resulting in the "waste" of usable pyridine compound in the form of nicotinamide.
Action de l'amphotéricine B sur la composition en stérols de Kluyveromyces bulgaricus et Kluyveromyces lactis
Authors: Coulon J. , Hakkou A. , Mpona-Minga M. , Bonaly R.
Published: May 2010

The degree of sensitivity of the yeasts Kluyveromyces bulgaricus and K. lactis to amphotericin B is linked to a difference in the sterol composition of their membranes. No direct proportionality was found between sensitivity and the quantity of sterols present. At sublethal doses, amphotericin B perturbed sterol synthesis, resulting in ergosterol precursor accumulation. An ergosterol pathway is proposed for Kluyveromyces. [Translated by the journal]
Isolation of nonobligate bacterial predators of bacteria from soil
Authors: Sillman Carl E. , Casida Jr. L. E.
Published: May 2010

A procedure is described for the isolation from soil of various Gram-positive and Gram-negative, nonobligate, bacterial predators of bacteria.
Histochemical and biochemical urease localization in the periplasm and outer membrane of two Proteus mirabilis strains
Authors: McLeanl Robert J. C. , Cheng K.-J. , Gould W. Douglas , Nickel J. Curtis , Costerton J. William
Published: May 2010

Proteus mirabilis, a gram-negative bacillus, is often implicated in the formation of infections kidney stones. As ureolytic activity of this organism is thought to play a major role in its pathogenesis, we adapted our recently described urease localization technique to visualize urease activity in vivo. Urease activity was ultra structural] y localized in two clinically isolated P. mirabilis strains by precipitating the enzymatic reaction product (ammonia) with sodium tetraphenylboron. Subsequent silver staining of the cells revealed urease activity to be predominately associated with the periplasm and outer membranes of each strain. Biochemical measurements of urease activity in P. mirabilis cell fractions correlated well with histochemical observations in that the majority of urease activity was associated with the periplasm. Membrane-bound urease activity of these strains was associated mainly with the peptidoglycan in the detergent-insoluble (outer membrane) fraction.
Growth and thermal inactivation of Listeria monocytogenes in cabbage and cabbage juice
Authors: Beuchat L. R. , Brackett R. E. , Hao D. Y.-Y. , Conner D. E.
Published: May 2010

Studies were done to determine the interacting effects of pH, NaCl, temperature, and time on growth, survival, and death of two strains of Listeria monocytogenes. Viable population of the organism steadily declined in heat-sterilized cabbage stored at 5 °C for 42 days. In contrast, the organism grew on raw cabbage during the first 25 days of a 64-day storage period at 5 °C. Growth was observed in heat-sterilized unclarified cabbage juice containing ≤5% NaCl and tryptic phosphate broth containing ≤10% NaCl. Rates of thermal inactivation increased as pH of clarified cabbage juice heating medium was decreased from 5.6 to 4.0. At 58 °C (pH 5.6), 4 × 106 cells/mL were reduced to undetectable levels within 10 min. Thermal inactivation rates in clarified cabbage juice (pH 5.6) were not significantly influenced by the presence of up to 2% NaCl; however, heat-stressed cells had increased sensitivity to NaCl in tryptic soy agar recovery medium. Cold enrichment of heat-stressed cells at 5 °C for 21 days enhanced resuscitation. Results indicate that L. monocytogenes can proliferate on refrigerated (5 °C) raw cabbage which, in turn, may represent a hazard to health of the consumer. Heat pasteurization treatments normally given to cabbage juice or sauerkraut would be expected to kill any L. monocytogenes cells which may be present.
Biosynthetic studies on N-acetylmannosaminuronic acid containing teichuronic acid in Bacillus megaterium
Authors: Arakawa Hirohumi , Ito Eiji
Published: May 2010

The particulate enzymes obtained from four strains of Bacillus megaterium AHU 1240, AHU 1373, AHU 1375, and T catalyzed the synthesis of a polysaccharide and glycolipids from UDP-N-acetylmannosaminuronic acid, UDP-N-acetylglucosamine, and UDP-glucose. Chemical studies involving Smith degradation, acid hydrolysis, and N-acetylation revealed that the polysaccharide product has a backbone made up of trisaccharide repeating units comprising glucose, N-acetylmannosaminuronic acid, and N-acetylglucosamine and that the main oligosaccharide moieties of the glycolipids were identical with N-acetylmannosaminuronosyl-N-acetylglucosamine and glucosyl-N-acetylmannosaminuronosyl-N-acetylglucosamine. Incubation of the disaccharide-linked lipid with each particulate enzyme in the presence of UDP-glucose produced the trisaccharide-linked lipid and a polysaccharide. It is therefore suggested that in this polysaccharide-synthesizing system the repeating unit is formed on a carrier lipid from appropriate nucleotide derivatives first and the polymerization of the units then occurs to synthesize the backbone while the growing chain remains in pyrophosphate linkage to the carrier lipid presumed to be undecaprenol.
Oxygen tolerance of uptake hydrogenase in Azospirillum spp.
Authors: Fu Changlin , Knowles Roger
Published: May 2010

Uptake hydrogenase in Azospirillum lipoferum and A. amazonense was studied in vivo under N2-fixing and NH4Cl-grown conditions. N2-flxing cultures of both A. lipoferum and A. amazonense showed significant uptake-hydrogenase activities which reached their maximum in late log phase, N2-fixing A. amazonense had 5 times higher H2 uptake activity than N2-fixing A. lipoferum. Uptake-hydrogenase activities of both species were negligible in NH4Cl-grown cells. However, sparging with H2 during growth caused over a 100-fold induction of uptake-hydrogenase activities, and prolonged the activities into stationary phase, suggesting that hydrogenase synthesis requires exogenous H2 as inducer. Oxygen-dependent uptake-hydrogenase activity in A. amazonense was almost unaffected by 20 kPa O2, whereas in A. lipoferum and A. brasilense activities were inhibited by 40 and 100%, respectively, in 20 kPa O2. Air caused a strong repression of hydrogenase synthesis in both species. Nitrogenase was roughly equally O2 sensitive in all three species.
Electrophoretic studies on the cell envelope of a spina-producing marine pseudomonad
Authors: Hoyle B. D. , Easterbrook K. B.
Published: May 2010

The effect of physiological parameters known to determine the transition from unspined to spined phenotype in marine pseudomonad D71 has been evaluated using electrophoretic techniques. The levels of at least four protein species (65, 42, 21, and 14 kilodalton (kDa)) in whole-cell lysates were affected. The 65-, 42-, and 14-kDa species were shown to be the major constituents of the outer membrane isolated by gradient separation of spheroplast lysate or detergent dissociation. Both the 42- and 21-kDa species were detected in immunoblots of outer membrane using antispinin antiserum exhaustively preabsorbed with unspined cells. The 21-kDa species was detected in both unspined and spined outer membrane, whereas the 42-kDa species, which migrated with the same mobility as purified spinin, was detected only in spined outer membrane. The 65-kDa species was no longer immunodetected and so likely represented a surface-exposed polypeptide common to both phenotypes. The structure and content of the lipopolysaccharide as determined by electrophoretic analysis was unchanged during the transition in phenotype. Lipopolysaccharide could not be detected in untreated whole-cell lysates, but could be detected chemically and electrophoretically after digestion of the cells. Comparison with LPS species from Salmonella minnesota indicated a deep-rough structure.
Structure of the exocellular D-glucan produced by Neisseria polysaccharea
Authors: Riou Jean-Yves , Guibourdenche Martine , Perry Malcolm B. , MacLan Leann L. , Griffith Douglas W.
Published: May 2010

Neisseria polysaccharea (LNP 462, NCTC 11858), proposed as a prototype strain constituting a new taxon in the genus Neisseria, produces copious amounts of polysaccharide when grown on agar containing 1–5% sucrose. Plate-grown cells produced an exocellular polysaccharide which was composed of D-glucose, had [α]D +222° (water), and was shown from composition, specific optical rotation, methylation, enzymic hydrolysis, and 13C nuclear magnetic resonance studies to have an amylopectinlike structure containing mainly 1,4-iinked α-D-glucopyranosyl residues, but also containing ca. 6% 4,6-di-O-substituted α-D-glucopyranosyl branch points.