bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethanol production by a newly isolated anaerobe, Clostridium saccharolyticum: effects of culture medium and growth conditions
Authors: Murray William D. , Khan A. W.
Published: May 2010

Clostridium saccharolyticum was shown to ferment glucose, cellobiose, and xylose to CO2, H2, ethanol, acetate, and lactate. The addition of 0.12 M CaCO3 and 1% yeast extract (w/v) to the glucose medium was found to shift the ethanol–acetate mole ratio from 1.36 to 2.6. Although the addition of exogenous H2 (240 kPa) did not affect the growth of C. saccharolyticum, it did alter the pattern of fermentation products. Both H2 and acetate formation decreased, while ethanol production increased. Ethanol production also increased at the expense of H2 and acetate when C. saccharolyticum was incubated without shaking. Stationary incubation under a H2 headspace (standard temperature and pressure) resulted in an ethanol concentration, at 25 °C, of 1.7% (v/v), an efficiency of conversion of 1.8 mol ethanol/mol glucose, and ethanol–acetate ratios of 7.6 at 35 °C and 9.4 at 20 °C. These results indicate that H2 concentration plays a significant role in the regulation of C. saccharolyticum catabolism.
Effect of subinhibitory concentrations of antimicrobials on meningococcal adherence
Authors: Salit Irving E.
Published: May 2010

Meningococci adhere to human pharyngeal cells and agglutinate erythrocytes. These events are dependent upon pili and are reduced by encapsulation. The effect of subinhibitory concentrations of seven antimicrobials on meningococcal adherence, piliation, hemagglutination (HA), and bacterial proteins was studied to determine their potential for modifying virulence. Piliation was reduced by most antibiotics but was most markedly (> 70%) reduced by rifampin, tobramycin, and VCN (vancomycin, colistin, and nystatin). Bacterial proteins as determined by sodium dodecyl sulphate – polyacrylamide gel electrophoresis were altered: tetracycline, sulfamethoxazole, rifampin, and VCN caused loss of a 43–45 K protein and a general decrease in all stainable protein bands, while erythromycin, ampicillin, and tobramycin only caused an increase in a 28 K protein. HA was reduced by ampicillin, tobramycin, erythromycin, and VCN but interstrain variability was present. Epithelial cell adherence was diminished by an average of 45% compared to controls. The meningococcal strains lost HA, piliation, and adherence in the same rank order, however, there was no significant rank correlation of antibiotic inhibitory activities on these parameters. These results indicate that subinhibitory antibiotic concentrations reduce meningococcal piliation and alter other bacterial proteins; these changes are associated with diminished adherence and hemagglutination, alterations which may be markers of meningococcal virulence.
Relationship of the internal solute composition to the salt tolerance of Halomonas elongata
Authors: Vreeland Russell H. , Mierau Bradley D. , Litchfield Carol D. , Martin Eugene L.
Published: May 2010

The recently described genus Halomonas contains bacteria which are extremely tolerant to salt. The basis for this halotolerance was studied in cells grown in a chemically defined medium containing 0.05, 1.37, or 3.4 M NaCl. The organisms increase the intracellular concentration of sodium and calcium as well as glutamic acid and alanine as the concentration of NaCl in the growth medium increases. The data indicate that in high salt concentrations the osmotic pressure increase associated with those internal changes detected in this study does not balance the changes in the external osmotic pressure.
Pseudomonas aeruginosa exoproducts as pulmonary virulence factors
Authors: Cash Howard A. , Straus David C. , Bass Joseph A.
Published: May 2010

An experimental animal model of chronic pseudomonas pneumonia was used to document the production of potential virulence factors by Pseudomonas aeruginosa during the infection. The production of exotoxin A, proteolytic enzymes, and the serotype-specific lipopolysaccharide and slime-layer antigens during the infection was examined by solid-phase radioimmunoassay of serum from infected rats and by indirect immunofluorescence tests of their lung tissue. Rats inoculated intratracheally with purified bacterial exoproducts, delivered alone or in combination, developed pulmonary histopathology similar to that induced by the experimental infection. The results indicate that these exoproducts are produced during the course of the pulmonary infection and suggest that they are involved in the observed lung pathology.
Effect of incubation atmosphere and temperature on isolation of Campylobacter jejuni from human stools
Authors: Wang Wen-Lan L. , Luechtefeld Nancy W. , Blaser M. J. , Reller L. B.
Published: May 2010

To determine the optimal conditions for isolation of Campylobacter jejuni from human fecal specimens, we compared incubation atmospheres that contained about 5, 10, and 15% oxygen with the 17% oxygen produced in candle jars and also compared incubation temperatures of 37 and 42 °C. At 42 °C, C. jejuni was isolated from all 16 specimens; however, colony sizes were larger when plates were incubated in 5 and 10% oxygen than in the other two atmospheres. At 37 °C some positive cultures were missed in 15% oxygen and in the candle jar. The largest colony sizes were obtained in 5% oxygen. For each atmospheric condition tested, the colonies were larger at 42 than at 37 °C. When incubation is done at 42 °C, use of a candle jar is adequate; however, at 37 °C candle jars should not be used for isolation of C. jejuni from human feces.
Selective degradation of biphenyl and methylbiphenyls in crude oil by two strains of marine bacteria
Authors: Fedorak P. M. , Westlake D. W. S.
Published: May 2010

Bacterial isolates were obtained from marine sediment and water enrichment cultures which had been maintained for 3 years by monthly transfers on artificial seawater with Prudhoe Bay crude oil as the sole carbon source. Capillary gas chromatographic analyses showed that two isolates selectively degraded only biphenyl, 3-methylbiphenyl, 4-methylbiphenyl, and three other minor, unidentified compounds in the aromatic fraction. No degradation was detected in the saturate fraction, nor in the sulfur heterocyclic component of the oil. When grown on any of the pure biphenyls, these isolates produced a transient, yellow intermediate which had the spectrophotometric characteristics of α-hydroxymuconic semialdehydes. Growth on either methylbiphenyl compound produced a methylbenzoic acid, indicating that the nonmethylated ring was the first to be cleaved. The isolates, identified as Alcaligenes sp. and Acinetobacter sp., were also able to grow on benzoic acid, 3-, and 4-methylbenzoic acids, indicating that they could further metabolize the aromatic acid intermediates.
Ochratoxin production by Aspergillus ochraceus as affected by methionine and structurally related compounds
Authors: Lisker N. , Paster N. , Chet I.
Published: May 2010

When 10−2 M of L- or D-methionine was added to a synthetic medium containing xylose as the sole carbon source, ochratoxin production by Aspergillus ochraceus was strongly inhibited. At that concentration methionine derivatives, e.g., α-methyl-DL-methionine, DL-methionine sulfoxide, and L-methionine sulfone, did not inhibit ochratoxin production, whereas DL-methionine S-methyl sulfonium chloride (MMSC) inhibited ochratoxin production to a large extent. L-Methionine, as well as MMSC, also completely inhibited sclerotia formation, while D-methionine and DL-methionine sulfoxide caused only a partial inhibition. At lower concentrations (10−3 and 10−4 M), none of the compounds exhibited inhibitory effects. In cases where strong ochratoxin inhibition was detected, fungal radial growth or mycelial dry weight was inhibited by only 10–25%, while the initial pH of the medium dropped from ~6.5 to ~4.4–5.0. Adjustment of the initial pH of media supplemented with 10−2 ML-methionine, D-methionine, or MMSC to a pH of ~7.8 did not change the inhibitory effects on ochratoxin production in media containing L-methionine. On the other hand, sclerotia formation was restored in all three treatments.
Evaluation of competitive ability of Rhizobium meliloti strains for nodulation in alfalfa
Authors: Peterson E. A. , Sirois J. C. , Berndt W. B. , Miller R. W.
Published: May 2010

A method was developed for determination of the competitive ability of selected Rhizobium meliloti strains based on recovery from nodules and identification with commercially available antibiotic sensitivity disks. Four strains isolated from soil were used as inocula for alfalfa seedlings under controlled conditions in all possible two-, three-, and four-way combinations and alone as controls. One of the test strains readily formed nodules, but had low expressed nitrogenase activity when used alone. In contrast, another strain with high nitrogenase activity was found to be distinctly noncompetitive with the other strains, based on frequency of recovery from nodules. Nitrogenase activities of groups of plants resulting from growth with some inoculum mixtures showed evidence of linear additivity of the activities based on frequency of recovery of the strains from nodules and the activity of control plants inoculated with single strains. Synergistic responses were found for other inoculum mixtures. Likewise, competitive ability of inoculum strains in the four-way mixtures was not wholly predictable from results obtained in two- and three-way tests, indicating some modification of competitive abilities in multiple-inoculum mixtures. Occupancy of nodules by two strains was found to occur at very low frequency with multiple-strain inocula. The noncompetitive strain was never found in double occupancy with the other strains.
Complementary DNA – 25S ribosomal RNA hybridization: an improved method for phylogenetic studies
Authors: Baharaeen Siavash , Melcher Ulrich , Vishniac Helen S.
Published: May 2010

In a new combination of techniques for ribosomal RNA hybridization, complementary DNA is synthesized on 25S ribosomal RNA fragments generated by mild alkali treatment, by the enzymatic addition of polyadenylic acid tails, hybridization of these tails with oligo deoxyribosylthymine, and reverse transcription in the presence of tritiated TTP. Hybridization reactions are performed in solution. Heteroduplexes are collected on diethylaminoethylcellulose filter discs after treatment with S1 nuclease. The problems presented by secondary rRNA structure are avoided by denaturation before reverse transcription and before hybridization. The high percentage of duplex formation (78–87%), the low standard deviation of relative binding (averaging ± 1.00330% relative binding), and small differences in reciprocal hybridizations (1.71–5.18% relative binding), as well as the elimination of complications resulting from differences in the number of rRNA cistrons in nuclear DNA, make this method preferable to the membrane-filter technique commonly used in phylogenetic classifications based on the homology of large rRNAs.
Toxicity of radiation-resistant strains of Bacillus thuringiensis (Berl.) to larval Plutella xyloStella (L.)
Authors: Jangi M. Sanusi , Ibrahim Hasan
Published: May 2010

A total of 24 isolates of Bacillus thuringiensis (Berliner), resistant to a γ-radiation dose of 100 krad, were screened for their toxicity to larval silkworms, Bombyx mori (L.), and 15 of them were subsequently tested for their toxicity to larval diamond-back moth, Plutella xylostella (L.). The LC50's of these isolates to B. mori ranged from 1.6 × 105 to 6.0 × 103 spores/mL or from 5.9 to 0.3 μg cellular protein/mL. The irradiation treatment produced isolates which were significantly more toxic to P. xylostella (LC50 < 8.1 × 104 spores/mL or 3.7 μg cellular protein/mL) and (or) or less toxic to B. mori (LC50 > 2.3 × 104 spores/mL or 1.0 μg cellular protein/mL) than the parent commercial strain.
Études d'infections mixtes anaérobies comportant Bacteroides gingivalis
Authors: Grenier D. , Mayrand D.
Published: May 2010

The infectiousness of several combinations of bacteria containing Bacteroides gingivalis and other bacteria associated with periodontal diseases was evaluated by subcutaneous injection to guinea pigs. Among the seven mixtures studied, only one permitted the development of an infection easily transmissible to a second guinea pig; this bacterial mixture was composed of B. gingivalis, Fusobacterium nucleatum, Eubacterium saburreum, and Capnocytophaga ochracea (formerly Bacteroides ochraceus). Owing to its ability to synthesize many lytic enzymes and potentially cytotoxic products, B. gingivalis represented the most virulent species of the mixture. Results from in vitro studies suggest that the development of B. gingivalis in the infected animal depends on the growth of C. ochracea. Succinic acid produced in large amount by C. ochracea seems to be one of the growth factors used by B. gingivalis.[Journal translation]
Lectin-binding activity and antibody response with Pseudomonas paucimobilis and Flavobacterium multivorum
Authors: Smalley David L. , Bradley Mary E.
Published: May 2010

Pseudomonas paucimobilis and Flavobacterium multivorum (formerly Group IIK biotype 1 and biotype 2, respectively) showed lectin-binding activity with Helix aspersa and no activity with eight other well-characterized lectins. Microagglutination titrations and immunodiffusion precipitation revealed specific antibody activity to immunizing antigens. However, no major antigens were found to be common from crude antigen preparations of P. paucimobilis and F. multivorum when tested against opposing antisera.
Factors affecting the release of outer membrane from a gram-negative marine bacterium
Authors: Laddaga Richard A. , MacLeod Robert A.
Published: May 2010

Suspending cells in 0.5 M sucrose was shown to be an essential step in the wash procedure used to remove the outer membrane from Alteromonas haloplanktis 214. Reducing the length of time the cells were suspended in 0.5 M sucrose and lowering the temperature of the sucrose solution from 25 to 4 °C reduced the extent of release of or damage to the outer membrane as determined by observation of thin sections of the cells by electron microscopy, the extent of conversion of rod-shaped cells to spheres by lysozyme, and the percentage release of alkaline phosphatase. The protease inhibitor phenylmethylsulfonyl fluoride, at a concentration which inhibited over 90% of the protease activity in a sonicated cell preparation and 79% of the activity in cells pretreated with the inhibitor, failed to affect the extent of release of outer membrane from the cells as determined by electron microscopy. The findings are consistent with previous conclusions that interaction of salts with polyanionic macromolecules are required to maintain the integrity and permeability properties of the outer membrane of this organism.
Association of methanogenic bacteria with rumen protozoa
Authors: Krumholz Lee R. , Forsberg Cecil W. , Veira Douglas M.
Published: May 2010

Methanogenic bacteria superficially associated with rumen entodiniomorphid protozoa were observed by fluorescence microscopy. A protozoal suspension separated from strained rumen fluid (SRF) by gravity sedimentation exhibited a rate of methane production six times greater (per millilitre) than SRF. The number of protozoa (per millilitre) in the protozoal suspension was three times greater than that of SRF; however, the urease activity of this fraction was half that of SRF. The methanogenic activity of SRF and the discrete fractions obtained by sedimentation of protozoa correlated with the numbers of protozoa per millilitre in each fraction. Gravity-sedimented protozoa, washed four times with cell-free rumen fluid, retained 67–71% of the recoverable methanogenic activity. Thus it is evident from our observations that many methanogens adhere to protozoa and that the protozoa support methanogenic activity of the attached methanogens. When protozoa-free sheep were inoculated with rumen contents containing a complex population of protozoa, methanogenic activity of the microflora in SRF samples was not significantly enhanced.
Unusual properties of a new division mutant of Escherichia coli
Authors: Drapeau G. R. , Chausseau J. P. , Gariépy F.
Published: May 2010

The properties of a division mutant of Escherichia coli were investigated. At 42 °C, this mutant forms nonseptate, multinucleate, filamentous cells typical of division mutants, and at the permissive temperature, is sensitive to ultraviolet (UV) irradiation. Temperature and UV sensitivities are probably due to a single mutation. The mutant phenotype is dominant to wild type. The mutant cells make DNA nearly as effectively as control cells at 42 °C or following UV irradiation. They exhibit normal host-cell reactivation capacities and can express all manifestations of the SOS response with the exception of Weigle reactivation. The genetic lesion which mediates this pleiotropic effect is located very close to the leu locus of the linkage map.
Solubilization of the extracellular membranous carboxymethylcellulase of Bacteroides succinogenes by trypsin
Authors: Groleau D. , Forsberg C. W.
Published: May 2010

It was previously reported that 50 to 62% of the extracellular carboxymethylcellulase (CMCase) activity of cultures of Bacteroides succinogenes grown on cellulose was associated with membrane fragments or vesicles. It has now been found that most of the membranous CMCase can be released from the membrane fragments by treatment with bovine pancreatic trypsin at 25 °C. Trypsin also releases most of the membranous xylanase activity. Over 90% of each of the CMCase and xylanase activities released by trypsin was associated with components of molecular weights less than 43 000. The low molecular weight CMCase released by trypsin appeared heterogeneous in charge, although not in size. This CMCase component was slightly smaller than the low molecular weight CMCase naturally present in the crude extracellular fraction. Treatment of intact cells with trypsin did not release an appreciable portion of the cell-bound CMCase activity of cells grown on either cellobiose or cellulose.
The detection of positive blood cultures in children using the acridine orange, gram, and methylene blue stains
Authors: Scolea Jr. Leonard J. La , Baldigo Susan M.
Published: May 2010

The efficacy of the acridine orange (AO), gram (G), and methylene blue (MB) microscopic procedures was analyzed using positive blood cultures monitored by a radiometric procedure (Bactec) in children. Sixty-eight positive cultures included the following isolates: Haemophilus influenzae type b, Neisseria meningitidis, Streptococcus pneumoniae, Enterobacteriaceae, Staphylococcus aureus, Candida spp., and seven other pathogens. The MB stain yielded the highest detection rate, 99%, in comparison with 94 and 93% for the AO and G stains, respectively. Since the MB stain yielded comparable results to the AO procedure with no requirement for a fluorescent microscope, the former method is recommended for confirming the presence and initial characterization of microorganisms in blood cultures monitored by Bactec from children.
FP2 plasmid curing in Pseudomonas aeruginosa
Authors: Potter Andrew A. , Loutit John S.
Published: May 2010

A procedure for the elimination of the IncP-8 plasmid FP2 from Pseudomonas aeruginosa strain 1 was developed. The procedure consists of freezing cells, competent for transformation, in 15% glycerol at −70 °C for at least 48 h and screening survivors for loss of mercuric chloride resistance. Curing frequencies of 0.5% were achieved only in host cells carrying a dht mutation (unable to convert thymine to dihydrothymine).
Characterization of N2-fixing bacteria associated with sweet potato roots
Authors: Hill Walter A. , Bacon-Hill Pansy , Crossman Stafford M. , Stevens Clauzell
Published: May 2010

Nitrogenase activity has been found associated with roots of sweet potato (Ipomoea batatas (L.) Lam). The objective of this investigation was to characterize N2-fixing isolates of the genus Azospirillum found in association with roots of different sweet potato cultivars. Five cultivars ('Carver', 'Jewel', 'Rojo Blanco', 'Centennial', 'Southern Queen') were grown in greenhouse pots on Norfolk sandy loam at pH 6.5 for periods of 1 to 3 months. Enrichment cultures of fibrous and storage root samples were grown on N-free semisolid malate medium at 35 °C. Sixteen bacterial isolates with taxonomic characteristics similar to those of Azospirillum were isolated from the five cultivars. Nitrogenase activities of single colonies grown in semisolid media for 30 h ranged from 32 to 472 nmol C2 H4∙culture−1∙h−1. The isolates were characterized by their acidification of carbon sources, ability to reduce nitrate, and morphology.
Morphological and physiological characteristics and lipopolysaccharide composition of N2-fixing (C2H2-reducing) root-associated Pseudomonas sp.
Authors: Haahtela Kielo , Helander Ilkka , Nurmiaho-Lassila Eeva-Liisa , Sundman Veronica
Published: May 2010

A dinitrogen-fixing Pseudomonas sp. was isolated from the roots of the grass Deschampsia caespitosa. The motile organism, which had 4 to 10 polar flagella, was gram negative, obligately aerobic, oxidase positive, arginine dihydrolase positive, and fluorescent. To verify API 20B, API 20E, and Oxi-Ferm identifications, as well as results from standard microbiological tests and electron microscopic examinations, which all indicated the organism to be a Pseudomonas, we analyzed its lipopolysaccharide. The lipopolysaccharide contained neutral sugars, phosphorus, heptose, hexosamine, 2-keto-3-deoxyoctonate, and fatty acids, which were dodecanoic, 3-hydroxydecanoic, 2-hydroxydodecanoic, and 3-hydroxydodecanoic acids. Both the qualitative and quantitative compositions resembled known data of the genus Pseudomonas. Dinitrogen fixation, determined as C2H2 reduction in semisolid medium, was supported by several carbon sources including malate and glucose. The N2 fixation activity was decreased if the oxygen concentration of the gas phase was lowered to one-tenth of atmospheric concentration. The highest specific nitrogenase activity recorded was 954 nmol C2H4/mg bacterial protein per hour, which is about 30% of that noted for Azospirillum lipoferum used as reference.
Effect of Azospirillum inoculation on yield of field-grown wheat
Authors: Kapulnik Yoram , Sarig Shlomo , Nur Israel , Okon Yaacov
Published: May 2010

Two cultivars of Triticum aestivum and T. turgidum were inoculated with bacteria of the genus Azospirillum in field experiments carried out in the Northern Negev and Bet Shean Valley. The results showed significant increases in yield of grain and foliage. There were significant increases in the number of fertile tillers per unit area and in the nitrogen yield. The possible mechanisms by which Azospirillum inoculation benefited wheat and other crops are discussed.
Estimating the true cost of dinitrogen fixation by nodulated plants in undisturbed conditions
Authors: Warembourg F. R.
Published: May 2010

Either symbiotic or nonsymbiotic N2 fixation in association with higher plants requires an appreciable amount of energy. This is mostly supplied by current photosynthesis, but an exact estimation of the true cost of the process is rather difficult. Simultaneous exposure of the association to 14CO2 and 15N2 for 1 day, analysis of labelled CO2 produced by soil respiration, and determination of N2 fixation make it possible to quantify the true respiratory cost associated with fixation. Preliminary trials with soybean suggest an amount of 2.5–7 mg C/mg of N2 fixed.
Nitrogenase activity during chinook snowmelt sequences by Nostoc commune in Stipa–Bouteloa grassland
Authors: Coxson D. S. , Kershaw K. A.
Published: May 2010

Inactivation of the nitrogenase enzyme in winter has been observed for many terrestrial cyanophytes of north temperate habitats. In southern Alberta frequent winter chinook activity causes repeated snowmelt sequences. The pattern of nitrogenase activity in these periods has been examined (acetylene-reduction technique) over several snowmelt periods. Nostoc collected from snowmelt pockets was immediately assayed for nitrogenase activity under laboratory (20 °C, 200 E∙m−2s−1 photosynthetically active radiation (PAR)) and field (ambient light and temperature) conditions. Air and thallus temperatures for a typical snowmelt sequence rose from −20 to +5 and −5 to +20 °C, respectively, as chinook warming progressed. Activity on initial snowmelt emergence was 420 nmol C2H4∙g−1∙h−1, rising to 1050 nmol after 7 h, monitored in lab conditions. Field activity reached 90 nmol after 4 h, ceasing at 1800 as temperatures fell below 0 °C. Laboratory rates at morning thaw, day 2, were 1040 nmol, while field activity (3 °C, 900 μE) was 800 nmol. By midday laboratory rates reached 1198 nmol, while field rates (10 °C, 1500 μE) were 1077 nmol. Although these rates are well below those at the temperature optimum of 35 °C (6805 nmol), clearly no winter inactivation of the nitrogenase enzyme occurs here. Cumulative activity over winter chinook sequences may well exceed that occurring during infrequent summer hydration.
Dinitrogen fixation by a mature Ceanothus velutinus (Dougl.) stand in the Western Oregon Cascades
Authors: McNabb D. H. , Cromack Jr. K.
Published: May 2010

Dinitrogen fixation was measured in a 17-year-old snowbrush, Ceanothus velutinus var. velutinus (Dougl.), stand in the Western Oregon Cascades. Diurnal and seasonal rates of nitrogenase activity were measured in the field using the C2H2 reduction technique. Snowbrush had a total biomass, estimated with equations developed, of 42 680 kg∙ha−1, including 750 kg∙ha−1 of nodule biomass. Snowbrush fixed N2 for approximately 240 days annually. Except during precipitation events or periods of low xylem pressure potentials, C2H2 reduction rates in the summer and fall were significantly correlated with soil temperature (R2 = 0.93**, n = 6). A diurnal variation in nitrogenase activity also was measured. The annual N2 fixation rate was estimated at approximately 101 kg N∙ha−1 (C2H2). Sustained periods of precipitation suppressed nitrogenase activity and reduced the estimate by about 19%. The annual N2 fixation rate is higher than previously reported for other mature stands and primarily is attributed to the maintenance of a large nodule biomass.
Autoradiographic technique for screening chemolithotrophic hydrogen-utilizing bacteria
Authors: Gowda T. K. S. , Watanabe I.
Published: May 2010

A simple autoradiographic method for screening aerobic H2-dependent chemolithotrophs is described. Bacteria were grown on agar plates in ambient air at 32 °C. Colonies from the plates were inoculated to H2-uptake agar plates by replica plating or streaking and incubated for 14 days in a desiccator under 20% H2, 2% O2, 5% CO2, and the balance N2, or 2% O2, 5% CO2, and the balance N2. The plates were further incubated for 9 days with 14CO2 in the above gas mixtures. The colonies were transferred to muslin cloth by replica method and the cloth was exposed to X-ray film for autoradiography. H2 was necessary for CO2 fixation under autotrophic conditions. By this technique, the predominance of H2-utilizing facultative aerobic chemolithotrophs among wetland rice root isolates was confirmed. The strains of Azospirillum lipoferum tested were found to fix 14CO2, but the A. brasilense strains tested were unable to fix 14CO2.
Bacterial chemotaxis to fungal propagules in vitro and in soil
Authors: Arora D. K. , Filonow A. B. , Lockwood J. L.
Published: May 2010

Erwinia herbicola, Pseudomonas fluorescens, and P. putida were strongly attracted in vitro to substances exuded by conidia of Cochliobolus victoriae and sclerotia of Macrophomina phaseolina, but not to phosphate buffer solution. Numbers of bacteria attracted to propagules of C. victoriae or M. phaseolina in an unsterilized sandy loam soil were significantly (P = 0.05) greater than background populations occurring in soil saturated with buffer. Chemotactic response was greater to C. victoriae than to M. phaseolina both in vitro and in soil. Results suggest that living fungal propagules may act as attractants for motile bacteria in soil.
Respiratory activity, molar growth yields, and ATP content in an Arthrobacter sp. ammonium-limited chemostat culture
Authors: Cacciari I. , Lippi D. , Ippoliti S. , Pietrosanti W.
Published: May 2010

Arthrobacter fluorescens was grown in chemostat culture under ammonium-limited conditions and respiratory activity; molar growth yields and ATP content were determined over a wide range of dilution rates. Within a range of dilution rates between 0.10 h−1 and 0.20 h−1, morphological transition occurred, the ratio of cocci to rods appearing inversely related to growth rate. Molar growth yields for both glucose and ammonium decreased with increasing dilution rates because of the higher intracellular polysaccharide content at the lower growth rates. Different metabolic activities were shown in cocci, in rods, and during morphogenesis. A sharp decrease in in situ and potential oxygen quotient (Q(O2)) and in ATP content was observed in the range of dilution rates in which morphological changes occurred.
Toxicité génétique du chlorure de méthylmercure (CH3HgCl) sur les mitochondries de Saccharomyces cerevisiae
Authors: Phipps J. , Miller D. R.
Published: May 2010

Among the strains of the yeast Saccharomyces cerevisiae we investigated, the organic form of mercury:methylmercury (II) does not seem to induce any cytoplasmic mutant "petite colonie" rho−. However, it induces a significant number of the erythromycin-resistant mutant Eryr. A dose response is shown. These effects are discussed in the view of the part that discrete DNA lesions could take in the explanation of the mechanism of toxicity of the organomercurial.
Production of deoxynivalenol and related compounds in liquid culture by Fusarium graminearum
Authors: Miller J. D. , Taylor A. , Greenhalgh R.
Published: May 2010

A liquid culture method for the production of deoxynivalenol and related compounds by Fusarium graminearum was developed. Major factors which stimulate the biosynthesis of these compounds include reduced oxygen levels, depletion of carbohydrate in the medium, pH, and possibly a low concentration of an organic nitrogen source. Isolates of F. graminearum were tested for the yields of four trichothecene mycotoxins and zearalenone in this system. The time course of acetyl deoxynivalenol, deoxynivalenol, and zearalenone in the fermentation was measured over a 21-day period against pH, glucose concentration, protein, fungal biomass, and ergosterol. A new ester of deoxynivalenol, 15-acetyl-deoxynivalenol, is reported from North American isolates of F. graminearum.
Derepression of F factor function in Salmonella typhimurium
Authors: Sanderson Kenneth E. , Kadam Sunil K. , MacLachlan P. R.
Published: May 2010

In Salmonella typhimurium LT2 the F factor of Escherichia coli K-12 replicates normally but is repressed; Flac+ cells give no visible lysis on solid media with male-specific phages, low frequency transfer of Flac+ (0.001–0.007 per donor cell), few f2 infective centers (0.002–0.006 per cell), and they propagate male-specific phages to low titers. Thus they display a Fin+ (fertility inhibition) phenotype. This repression, owing to pSLT, a 60 Mdal plasmid normally resident in S. typhimurium, was circumvented by the following materials: (i) Flac+ plasmids from E. coli with mutations in finP or traO; (ii) a S. typhimurium line which had been cured of pSLT; (iii) pKZl, a KmR plasmid in the same Inc group as pSLT, which caused expulsion of pSLT and made Fin− lines; (iv) F-Fin− mutants which originated spontaneously and which are present in most Hfr strains of S. typhimurium. Strains which are derepressed for F function by the above methods give visible lysis on solid media with male-specific phages, ca. 1.0 Lac+ recombinants per donor cell in conjugal transfer, ca. 0.82 f2 infective centers per cell, over 80% of cells with visible F pili, and propagation of male-specific phages to high titer. These data confirm earlier observations that pSLT represses F by the FinOP system. In addition, it shows that there is no other mechanism which represses F function in S. typhimurium. If donor function is derepressed by one of the above methods, and if rough recipient strains are used, F-mediated conjugation in S. typhimurium LT2 is as efficient as in E. coli K-12.
An improved method for measuring H2–CO2 uptake during growth of methanogenic bacteria
Authors: Ahring Birgitte Kiær , Westermann Peter
Published: May 2010

A technique for measuring the H2–CO2 uptake as a growth parameter for methanogenic bacteria cultured in Hungate tubes is described. This technique offers the possibility of flushing the headspace of the culture tubes while carrying out the measuring routine.
Metabolism of cinnamic, p-coumaric, and ferulic acids by Streptomyces setonii
Authors: Sutherland John B. , Crawford Don L. , Pometto III Anthony L.
Published: May 2010

Streptomyces setonii strain 75Vi2 was grown at 45 °C in liquid media containing yeast extract and trans-cinnamic acid, p-coumaric acid, ferulic acid, or vanillin. Gas chromatography, thin-layer chromatography, and mass spectrometry showed that cinnamic acid was catabolized via benzaldehyde, benzoic acid, and catechol; p-coumaric acid was catabolized via p-hydroxybenzaldehyde, p-hydroxybenzoic acid, and protocatechuic acid; ferulic acid was catabolized via vanillin, vanillic acid, and protocatechuic acid. When vanillin was used as the initial growth substrate, it was catabolized via vanillic acid, guaiacol, and catechol. The inducible ring-cleavage dioxygenases catechol 1,2-dioxygenase and protocatechuate 3,4-dioxygenase were detected with an oxygen electrode in cell-free extracts of cultures grown in media with aromatic growth substrates and yeast extract.
Induction of cellulase in Myceliophthora thermophila D-14
Authors: Sen Sribir , Abraham T. K. , Chakrabarty S. L.
Published: May 2010

Induction of cellulase complex with different carbon sources (monomers, dimers, polymers, etc.) was studied in Myceliophthora thermophila D-14. Lactose was found to be the best carbon source for the induction of cellulase. It was also noted that induction of cellulase biosynthesis occurred when inducers having β-linkages in their molecules were used.
Theoretical maximum and observed product yields associated with curdlan production by Alcaligenes faecalis
Authors: Phillips K. R. , Lawford H. G.
Published: May 2010

As a guide to both strain and process improvement and based on certain assumptions concerning both glucose and energy metabolism of the process organism, Alcaligenes faecalis var. myxogenes, the theoretical "maximum" carbon (glucose) substrate to product conversion efficiency (i.e., product yield) has been estimated for "curdlan-type" β(1 → 3)-glucan exopolysaccharide production in batch fermentations. Under nitrogen limitation, which promotes curdlan biosynthesis (μ = 0), the rate of glucose consumption for cellular maintenance energy (grams of glucose per gram of cells per hour) was approximately five times higher than under carbon limitation. The decrease in the theoretical "maximum" curdlan conversion efficiency of 74% to the average value of 50–56% was due primarily to the high maintenance coefficient of the nitrogen-starved culture.
Estimation du spectre de la dispersion aérienne de Bacillus thuringiensis
Authors: Smirnoff W. A. , Valéro J. R.
Published: May 2010

The present paper estimates the number of viable spores of Bacillus thuringiensis per droplet and reveals the importance of this data to improve B. thuringiensis treatments. For a given diameter, droplets from Futura formula contained two times more spores than droplets from the formulas used to date. It is preferable to have B. thuringiensis droplets larger than those of chemical insecticides. A Grumman AgCat aircraft calibrated to give the desired larger droplets resulted in successful B. thuringiensis treatments.
Spore germination and hyphal growth of a vesicular–arbuscular mycorrhizal fungus, Glomus mosseae (Gerdemann and Trappe), under decreased oxygen and increased carbon dioxide concentrations
Authors: Tacon F. Le , Skinner F. A. , Mosse Barbara
Published: May 2010

Spore germination and hyphal growth from spores of the vesicular–arbuscular endophyte Glomus mosseae have been studied under different oxygen and carbon dioxide tensions. Spores failed to germinate at low oxygen tension. This effect was reversible. However, mycelial growth from spores not preincubated in air was irreversibly damaged. The mycelial growth from preincubated spores was affected by oxygen tension. Between 21 and 3% oxygen, growth decreased slightly. Below 3% oxygen it decreased sharply. Again this effect was reversible. A tension of 5% carbon dioxide had no effect on spore germination, but reduced hyphal growth consistently at all oxygen tensions. This effect persisted when spores were subsequently returned to air.
Growth responses of isolated adhesive knobs of Dactylaria ellipsospora
Authors: Zachariah K.
Published: May 2010

The adhesive knob traps of the predatory fungus Dactylaria ellipsospora can be mechanically detached from their hyphal stalks and cultured in isolation. This serves as a stimulus for hyphal proliferation, the first hypha probably being the specialized penetration peg. Knob hyphae achieve a growth rate only one-fifth that of conidial hyphae. If isolated knobs are placed near air-dried nematodes, their hyphae exhibit a chemotropic response and later vigorous localized trophic activity which effects digestion of the carcass.
Effects of various physiochemical factors on microbial activity in peatlands: aerobic biodegradative processes
Authors: Williams Richard T. , Crawford Ronald L.
Published: May 2010

The quantitative relationships between the biodegradative activities of peatland microorganisms and several relevant physiochemical environmental parameters were examined. Temperature decrease from 30 to 4 °C was found to slow, but not eliminate, microbial activity (mineralization of 14C compounds to 14CO2). Microbial activity generally was higher at ambient peatland pH's (pH 3–4.5), rather than at more neutral pH's, in the media used. Low oxygen tension significantly decreased the metabolic activities of peatland surface-inhabiting microbes. Individual pure cultures isolated from peatlands exhibited different responses to decreasing pH, oxygen tension, and temperature; demonstrating great physiological diversity among peatland microbes. Concentrations of nutrients such as nitrogen and phosphorus appear not to limit severely most microbial activities in peatland habitats.
M-type 57 group A streptococcus bacteriocin
Authors: Simpson W. J. , Tagg J. R.
Published: May 2010

All 40 tested isolates of M-type 57 group A streptococci gave the same, highly characteristic inhibitory pattern (P-type 614) when tested by deferred antagonism using a set of nine indicator strains. One component of this inhibitory activity was attributed to the production of a bacteriocinlike substance, streptococcin A-M57 (SA-M57). Production of SA-M57 was enhanced by the presence of blood and also by growth at an alkaline pH. Partially purified SA-M57 was obtained from culture supernatants by a combination of ammonium sulphate fractionation and column chromatography. On Sephadex G-100 two different molecular weight forms (SA-M57α, > 100 000; SA-M57β, 33 000) were demonstrated. Both SA-M57 forms were protease and heat sensitive and had identical inhibitory activity against a collection of indicator bacteria. The adsorption to and rate of kill of sensitive cells by SA-M57 was enhanced in the presence of human plasma. Partially purified SA-M57 preparations were devoid of M-type 57 protein and curing studies showed that loss of SA-M57 did not correlate with loss of M protein production.
Phosphatidylglycerophosphate synthase activity in Saccharomyces cerevisiae
Authors: Carman George M. , Belunis Charles J.
Published: May 2010

Cytidine 5′-diphospho-1,2-diacyl-sn-glycerol (CDP-diacylglycerol):sn-glycerol-3-phosphate phosphatidyltransferase (phosphatidylglycerophosphate synthase, EC 2.7.8.5) activity was characterized from the mitochondrial fraction of Saccharomyces cerevisiae. The pH optimum for the reaction was 7.0. Maximum activity was dependent on manganese (0.1 mM), magnesium (0.3 mM), or cobalt (1 mM) ions and the nonionic detergent Triton X-100 (1 mM). The apparent Km values for CDP-diacylglycerol and glycerol-3-phosphate were 33 and 27 μM, respectively. Optimal activity was at 30 °C with an energy of activation of 5.4 kcal/mol (1 cal = 4.1868 J). Phosphatidylglycerophosphate synthase activity was thermally labile above 40 °C. p-Chloromecuriphenylsulfonic acid, N-ethylmaleimide, and mercurous ions inhibited activity. Phosphatidylglycerophosphate synthase activity was partially solubilized from the mitochondrial fraction with 1% Triton X-100.
A lipopolysaccharide-specific bacteriophage for Aeromonas salmonicida
Authors: Ishiguro E. E. , Ainsworth Teresa , Shaw D. H. , Kay W. W. , Trust T. J.
Published: May 2010

Cell wall lipopolysaccharide (LPS) was identified as the receptor for the Aeromonas salmonicida bacteriophage strain 55R-1. Mutants of A. salmonicida resistant to phage 55R-1 were unable to adsorb phage 55R-1 and were shown to be defective in LPS structure. Purified A. salmonicida LPS inactivated phage 55R-1, but the O-polysaccharide and the core oligosaccharide portions of the LPS were ineffective. These results suggest that lipid A was required for receptor activity. Antibodies directed against LPS also inhibited phage adsorption.
Rotavirus inactivation by chemical disinfectants and antiseptics used in hospitals
Authors: Sattar S. A. , Raphael R. A. , Lochnan H. , Springthorpe V. S.
Published: May 2010

Nosocomial outbreaks of rotaviral gastroenteritis are a common occurrence. Although proper disinfection practices in the hospital environment are considered to be important in the prevention and control of such outbreaks, very little information has been available on the rotavirus-inactivating capacity of chemical disinfectants and antiseptics commonly used in hospitals. In view of this, 11 such products were selected and screened for their capacity to bring about at least a 3 log10 reduction in the plaque titre of rotavirus SA-11 after a contact time of 1–30 min. Consept "D" (1:100), D.R.X. (1:80), Dustbane Germicidal (1:80), Hibitane, and Wescodyne (1:200) were found to be ineffective under these test conditions even in the absence of an added organic load. The virucidal capacity of Savlon (1:200) and Zephiran was completely neutralized when single-strength tryptose phosphate broth was added to the virus–disinfectant mixture to simulate an organic load. Cidex (2% acid glutaraldehyde), Proviodine (10% solution of povidone-iodine), Septisol (0.75% hexachlorophene), and Sana Rinse (70% isopropylalcohol, 0.1% hexachlorophene) were able to produce at least a 3 log10 (99.9%) reduction in the virus plaque titre even in the presence of added organic matter. These findings should be of help in the prevention and control of outbreaks of rotaviral diarrhea in the hospital environment.
A new inorganic pyrophosphate utilizing bacterium from a stagnant lake
Authors: Varma A. K. , Rigsby W. , Jordan D. C.
Published: May 2010

An apparently new species of Clostridium was isolated from mud samples obtained from a stagnant lake near Athens, Georgia. These organisms were able to utilize inorganic pyrophosphate as a source of energy for growth, a phenomenon representing the simplest ATP-generating system in the biological world.
Decrease in soil microbial activity and biomasses owing to nitrogen amendments
Authors: Söderström B. , Bååth E. , Lundgren B.
Published: May 2010

Microbial biomass and soil respiration rate decreased after application of 150 kg NH4NO3–N∙ha−1 to different coniferous forest podzols. The decrease was already found 3 months after fertilization and was still evident after 3–5 years. Changes in pH, organic matter, or water content in the soils could not explain the decreases. In laboratory experiments, several unfertilized forest soils were treated with 2 mg of NH4NO3–N or of urea–nitrogen∙g wet soil−1. The ammonium nitrate addition resulted in severe depressions of the respiration rates during and up to 175 days of incubation and the decrease was evident after about 1 week. The urea treatment initially increased the respiration rate of the soils, but this appeared to be a transitory effect.
Galactosamine inhibition of protein synthesis in Bacteroides thetaiotaomicron
Authors: Salyers Abigail A. , O'Brien M. , Kotarski S. F.
Published: May 2010

Galactosamine does not support growth of Bacteroides thetaiotaomicron. Despite this, galactosamine was more effective than utilizable carbohydrates such as glucose in preventing synthesis of the inducible enzymes α-glucosidase and chondroitin lyase. Galactosamine also stopped overall protein synthesis. By contrast glucose and other utilizable carbohydrates increased the rate of protein synthesis. Addition of glucose to bacteria which had been treated with galactosamine restored the ability of the bacteria to synthesize protein and to produce inducible enzymes. Moreover, when B. thetaiotaomicron was incubated with [1-14C]galactosamine for 30 min at 37 °C, about one-third of the label which was taken up by the cells comigrated with glucosamine-6-phosphate on a thin-layer chromatogram. Thus galactosamine appears to be phosphorylated by the bacteria. After 2 h incubation of the bacteria with [1-14C]galactosamine, there was a significant increase in the amount of label which could be extracted from acidified extracellular fluid with diethyl ether. This indicates that galactosamine can be metabolized to the level of volatile fatty acids. The rate of uptake of galactosamine and the amount of labeled fatty acids produced from galactosamine were both much lower than the values obtained when glucosamine was the substrate. Thus, although some metabolism of galactosamine occurs, the rate is apparently too slow to enable galactosamine to support growth of B. thetaiotaomicron.
The in vitro effect of Actinobacillus actinomycetemcomitans strain Y4 lipopolysaccharide on murine peritoneal macrophages
Authors: Barker Kathleen A. , Holt S. C.
Published: May 2010

Actinobacillus actinomycetemcomitans strain Y4 lipopolysaccharide (LPS) was examined for its in vitro effect on murine peritoneal macrophage morphology, viability, and lysosomal enzyme activity. Fifty micrograms of Y4 LPS per 106 macrophages resulted in macrophage activation, eliciting the release of acid phosphates (AcP), as well as the accumulation of intracellular AcP, without a loss in viability. There was also an increase in the number of organelles and cell-surface ruffles. One hundred or 250 μg of Y4 LPS caused flattening, rounding, and blebbing of the cell surface, as well as the release of large quantities of AcP and lactate dehydrogenase (LDH), within 5 min of exposure to the LPS. Alteration of cell ultrastructure occurred within 30 min, and extensive autophagocytosis by 24 h, indicative of cell injury. Short-term (less than 24 h) experiments appear necessary to distinguish between the effects of cell activation and cell death caused by A. actinomycetemcomitans Y4 LPS.
Swarming of Azospirillum brasilense on solid media
Authors: Hall Patrick G. , Krieg Noel R.
Published: May 2010

Azospirillum brasilense ATCC 29145, which possesses a single polar flagellum and also lateral flagella, exhibited swarming on the surface of nutrient broth containing 0.75% agar or 0.5% carrageenan. Various agents such as p-nitrophenylglycerol or sodium deoxycholate inhibited the swarming. Based on mutants lacking either polar or lateral flagella, the lateral flagella were responsible for the swarming on solid media, whereas the polar flagellum was responsible for swimming motility in liquid media.