bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunochemical characterization of Nocardia asteroides antigens: support for a single species concept
Authors: Kurup Viswanath P. , Piechura James E. , Ting Eve Y. , Orloski Julie A.
Published: May 2010

Nocardia asteroides strains are highly heterogeneous. They show morphological, physiological, and immunological differences. In a previous study, we delineated seven immunotypes of N. asteroides. In the present study, we compared the culture filtrate antigens of these immunotypes by antigen–antibody crossed-immunoelectrophoresis and by rocket electrophoresis. We have also compared the antigen preparations by two-dimensional electrophoresis. While unique components constitute the major portion of the components, the results indicate that similar components are present in the culture filtrates of all strains. This finding supports the view of retaining all the immunotypes in the species Nocardia asteroides rather than designating different species such as N. farcinica and N. sebivorans.
Survival of Pseudomonas solanacearum in soil, rhizosphere, and plant roots
Authors: Granada G. A. , Sequeira Luis
Published: May 2010

A new, selective medium was used to determine the ability of different strains of Pseudomonas solanacearum to survive in the soil or in association with plant roots in the greenhouse. When survival of two strains of race 1, two of race 2, and one of race 3 in a soil–sand mixture (ψ = −2 bars (1 bar = 100 kPa), 28 °C, was determined, populations of each strain declined at different rates, but none of the strains survived beyond 24 weeks. To study survival of P. solanacearum in the rhizosphere, seedlings of resistant hosts (pepper, tomato, castor bean) and presumed nonhosts (bean, corn) were inoculated by dipping their roots in a bacterial suspension and then replanted. Bacterial populations in the rhizosphere were determined at various intervals up to 33 weeks. The pathogen was not able to survive in the rhizosphere; when high populations were detected, they were associated with localized or systemic infection of the roots of plants that did not show wilt symptoms. When the roots of inoculated plants were collected at different times and then surface sterilized by immersing them in 70% ethanol for 5 min, high populations of the bacterium were recovered from many of the plants in each treatment. That infection was not the result of the artificial inoculation procedures used was shown in experiments in which presumed nonhost plants, such as bean, peas, soybean, corn, sorghum, and rice, were grown from seed planted in soil infested with strains of race 1. High populations of the bacterium were recovered from surface-sterilized roots throughout the growth cycle of these plants. Thus, long-term survival of P. solanacearum appeared to be correlated with its ability to infect plant roots.
Investigation of white-rot fungi for the conversion of poplar into a potential feedstuff for ruminants
Authors: Reade A. E. , McQueen R. E.
Published: May 2010

Five isolates of wood-rotting fungi were compared for their ability to increase the digestibility of poplar shavings. Homogenates of the fungi were inoculated into mixtures of 25 g of shavings and 100 mL of supplementary nutrient solution and incubated at 25 °C. The in vitro rumen digestibility of the products increased from 30% at the start of the fermentation to maxima of 72% with Polyporus anceps after 8 weeks, 64% with Ganoderma applanatum and 62% with Phanerochaete chrysosporium after 4 weeks, 61% with Polyporus versicolor after 3 weeks, and 42% with Fomitopsis ulmarius after 4 weeks. Fibre analysis showed a decrease in lignin as digestibility increased. Loss of carbohydrates occurred in all fermentations and continued after lignin loss ceased. Dry matter yield at the time of maximum digestibility ranged from 80 to 94% of the original dry matter. The highest digestibilities attained were similar to those of conventional roughage feeds for ruminants. This shows that this fermentation could form the basis of a practical system for converting poplar into a feedstuff.
Magnetic stimulation of polysaccharide accumulation in cultures of Streptococcus mutans
Authors: Adamkiewicz Vincent W. , Pilon Denis R.
Published: May 2010

Microscope slides, dipped 24 h into cultures of oral bacterium Streptococcus mutans, accumulated up to 66% more bacterial polysaccharide on the side of the slides facing north. Reversal of the magnetic field by 180° caused similar reversal of the preferential accumulation. The process of preferential accumulation becomes saturated at 1.7 gauss [Formula: see text].
Induced changes in the surface of Neisseria gonorrhoeae
Authors: Norrod E. Pinina , Burnham Judith S. , Williams Robert P. , Ding Ming-Jer
Published: May 2010

Growth of Neisseria gonorrhoeae strain F62 on medium containing pyruvate and a high ratio of cysteine to cystine resulted in functional and structural changes that are consistent with phenotypic changes in lipopolysaccharide. Both transparent (O−) and moderately opaque (O+) variants became more sensitive to killing by normal human serum and more resistant to killing by pyocin G, a bacteriocin from Pseudomonas aeruginosa. Electrophoresis of outer membranes in the presence of sodium dodecyl sulfate demonstrated differences also dependent upon the growth medium. When gels were treated with periodic acid and stained with silver, lanes containing outer membranes obtained after growth in the modified medium demonstrated two bands in addition to those independent of the growth medium. The enhancement of these additional bands by periodate treatment indicated that they represent material containing carbohydrate. The mechanism by which the changes in the growth medium affected the surface of N. gonorrhoeae is not known; however, the changes demonstrated by electrophoresis were dependent upon either the high concentration of cysteine or the high ratio of cysteine to cystine.
A new simple method for microbiological sampling of meat surfaces
Authors: Goulet J. , Lévesque G. , Moreau J. R. , Roth L. A.
Published: May 2010

A new method for sampling meat surfaces using abrasive discs has been tested against the spray gun technique already described by Clark (1965). Evenly inoculated beef and pork slices were sampled after 1, 48, and 120 h of incubation at 4 °C for beef and 1, 48, and 72 h at 4 °C for pork. The new method was slightly less efficient than the spray gun in recovering bacteria during the early stages of incubation but was about 600% more efficient after 72 and 120 h.
Pattern of protein degradation during germination of Streptomyces antibioticus spores
Authors: Guijarro J. A. , Suarez J. E. , Salas J. A. , Hardisson C.
Published: May 2010

The pattern of protein degradation during germination of Streptomyces antibioticus spores was studied by the pulse and chase technique. Two different protein fractions were found. First, a fraction of the proteins synthesized during the darkening process (20–30%) was quickly degraded in the 30 min following the labelling period. This rapid protein degradation was partially inhibited by protease inhibitors: p-chloromercuribenzoic acid, phenylmethylsulphonylfluoride, and o-phenanthroline. Second, the remaining 70–80% and the entire protein population formed during spore swelling and germ tube emergence were degraded with a lower and constant rate (3.3–6.0%/h). A stable mRNA fraction of the dormant spores was translated upon incubation of the spores in a minimal synthetic medium (MSM) or in distilled water. However, the degradation of these proteins did not occur unless the spores were then incubated in the MSM. A strong correlation between the degradation pattern of these proteins and that of those quickly degraded at the beginning of germination was observed. Protease activity in cell-free extracts of dormant spores was detected. Inhibition studies suggest the presence of serine, thiol, and metalloproteases. The protease activity, using casein as substrate, remained constant during the darkening process and started to increase progressively from the beginning of spore swelling.
Changes in bacterial populations in a clear-cut beech forest soil planted with spruce
Authors: Kauri Thu
Published: May 2010

A beech forest after clear-cutting was replanted with spruce. To study how this perturbation affected soil bacteria and their physiological capabilities, an investigation was undertaken 4 years after the change of forest type. Compared with an earlier study in the beech forest, from 1972 to 1975, conducted immediately before clear-cutting, bacterial numbers in the young spruce plantation had increased; an exception was the upper layer (A00), where the numbers decreased. The population densities of bacteria decomposing xylan, pectin, starch, cellulose, and chitin were estimated by a direct multipoint method. The numbers of bacteria in all the physiological groups studied were higher in 1979–1980, with the same exception as before (A00). The greatest changes occurred in the upper horizons. There were considerable changes in the soil environment after the former beech litter fall ceased; the forest floor became more exposed, and the ground vegetation changed. Changes took place in soil properties, such as organic matter and pH. A slight increase in pH was observed in all horizons except in A00, and organic matter increased in two of the horizons (A01/A1; A1).
A technique for preserving aerial fungal structures for scanning electron microscopy
Authors: King E. J. , Brown M. F.
Published: May 2010

A technique is described that employs vapor fixation and a simple vapor diffusion dehydration apparatus to minimize the disturbance of delicate fungal structures during preparation for scanning electron microscopy. The technique is applicable to fungi grown on agar media or on natural substrates.
Effect of triglycerides on the production of lipids and lipase by Mucor hiemalis
Authors: Akhtar M. Waheed , Mirza A. Qayyum , Nawazish M. Nadeem , Chughtai M. I. D.
Published: May 2010

The effect of triglycerides on the growth of Mucor hiemalis and the production of lipase and mycelial lipids was studied. Addition of 1% triglycerides to the fermentation medium was best for the mycelial as well as the broth lipase production. The added triglycerides seemed to be utilized through the formation of free fatty acids, and towards the end of the growth phase most of the triglycerides and their hydrolysis products were utilized. The mycelial lipase activity was maximum (66 U/g dry mycelium) at the end of the growth phase, while the maximal broth lipase activity (204 U/100 mL) was achieved after the cell lysis had started. The lipids produced per gram mycelia were high initially (260 mg/g dry weight at 48 h), reducing gradually later. With increase in growth the maximum mycelial lipids per 100 mL of culture medium was obtained after 96 h (176 mg/100 mL). The various fractions detected in the mycelial lipid extracts were sterol esters, triglycerides, free fatty acids, diglycerides, sterols, monoglycerides, phosphatidyl ethanolamine, phosphatidyl choline, and small amounts of an unknown polar lipid at all the stages of fermentation studied. Proportion between total neutral and total polar lipids remained nearly constant throughout fermentation.
Bactericidal photoproducts in medium containing riboflavin plus aromatic compounds and MnCl2
Authors: Chelala Cesar A. , Margolin Paul
Published: May 2010

Exposure to visible light of growth medium containing riboflavin and indole at low concentrations created photoproducts highly toxic to Salmonella typhimurium and other bacteria. No toxicity was detected in the dark or when either of these two components was present singly. Other aromatic compounds (serotonin, indole-3-acetic acid, indole-3-propionic acid, tryptophan, tyrosine, phenylalanine, and p-aminobenzoic acid) tested in place of indole produced various degrees of toxicity. The presence of MnCl2 significantly enhanced the toxicity. Addition of catalase eliminated the toxicity, indicating an important role for hydrogen peroxide.
Competitive adherence as a mechanism of bacterial interference
Authors: Bibel Debra Jan , Aly Raza , Bayles Charlene , Strauss Walter G. , Shinefield Henry R. , Maibach Howard I.
Published: May 2010

To determine whether competition among bacteria for specific attachment sites on host cells can explain bacterial interference, Staphylococcus aureus strain 502A was tested in turn against two different nasal coryneforms, a strain of Pseudomonas aeruginosa, and a virulent strain of S. aureus, all in the presence of nasal mucosal cells. Particularly examined was the influence of sequence in which bacteria were presented to the nasal cells in comparison with initial mixtures and individual suspensions. Results paralleled those observed in clinical prophylaxis: the bacterium first to adhere to the epithelial cells was able, under uniform conditions, to interfere with the colonization of subsequently added bacteria. Secondary adherence was not eliminated but substantially reduced, and was probably related to steric blockage by the initial colonizer and its particular ability to dissociate from the host cell.
Effect of temperature, duration of incubation, and pH of enrichment culture on the recovery of Campylobacter jejuni from eviscerated market chickens
Authors: Park C. E. , Stankiewicz Z. K. , Lovett J. , Hunt J. , Francis D. W.
Published: May 2010

To establish an enrichment system of high efficiency for recovery of Campylobacter jejuni from market chickens, the effects of the temperature, duration of incubation, and pH of the enrichment culture on the isolation of the bacterium were evaluated. Whole chickens or chicken parts in plastic bags were individually rinsed, and the washings filtered through cheesecloth. The cells were separated from the washings by centrifugation, and the pellet was inoculated into 100 mL of enrichment broth. Isolation of C. jejuni from poultry samples was significantly increased by incubating these samples in an enrichment medium at 42 °C as opposed to 35 °C; for 48 h as opposed to 24 h or 72 h; and at pH 7.0 as opposed to pH 6.0, 6.5, 7.5, or 8.0.
Comparative study of the beta-lactamase activity found in Achromobacter
Authors: Levesque Roger , Letarte Robert , Pechère Jean-Claude
Published: May 2010

A survey of 21 clinical isolates of Achromobacter species demonstrated a high level of β-lactamase activity in all strains tested. The β-lactamases were characterized by isoelectric focusing, purification by affinity chromatography, determination of molecular weight, immunological identity, and genetic analysis. At least three distinct patterns of β-lactamases were found in 19 strains. The kinetic values Km and Vmax measured by a microacidimetric method showed that all three types of enzymes are cephalosporinases and did not hydrolyse oxacillin, cloxacillin, and methicillin. Two of the three types of cephalosporinases studied, namely MULB 901 (isoelectric point (pI) 7.4) and MULB 905 (pI 9.3) are enzymes mediated by genes of chromosomal origin. The MULB 906 (pI 8.1) enzyme, however, which has been previously shown to be mediated by an 8.2 MDal nonconjugative plasmid, showed hydrolysis of cefoxitime, cefotaxin, and moxalactam by the bioassay. In all cases, β-lactamase synthesis appeared constitutive. This study confirms that β-lactamase activity is commonly found in Achromobacter and that these enzymes are different and of clinical interest when compared with those observed in other Gram-negative bacteria.
The pH-dependent uptake of putrescine by Pseudomonas acidovorans and its incorporation into bacteriophage DNA
Authors: Bruce D. L. , Warren R. A. J.
Published: May 2010

Lack of an active transport system prevents Pseudomonas acidovorans taking up putrescine under normal condition of growth. At pH 9.5, however, putrescine does enter the cell. That putrescine enters the intracellular pool is shown by its conversion to 2-hydroxyputrescine and spermidine after the cells are returned to pH 7.0. The accumulated putrescine can be used to label specifically the α-putrescinylthymine residues of bacteriophage [Formula: see text] DNA.
Nitrogen-fixing bacteria associated with plantation and orchard plants
Authors: Rao N. S. Subba
Published: May 2010

Rhizosphere soil of several plantation and orchard plants were analyzed to enumerate and isolate Azotobacter and Beijerinckia. Azospirillum was isolated from washed and surface-sterilized roots and 14 of the isolates were classified as A. lipoferum or A. brasilense. The ability of all these bacterial isolates to fix N2 in pure cultures on N-free media was established by Microkjeldahl and C2H2 reduction procedures. Motile bacteria capable of reducing triphenyltetrazolium chloride were found to be more abundant in xylem cells than in cortical cells of roots.
Response of maize plants to inoculation with azospirilla and (or) straw amendment in Egypt
Authors: Hegazi Nabil A. , Monib Mohamed , Amer Hussein A. , Shokr El-Sayed
Published: May 2010

A pot experiment was designed to investigate the effects of inoculation with Azospirillum and (or) straw amendment on growth of plants grown in Giza soils. Inoculation caused increases in plant dry weight (200%) and total N content (157%) of plants. These characters were correlated with increases in ATP production in rhizosphere (492%), nitrogenase activity (438%), and densities of Azospirillum sp. (116-fold). Addition of straw only (5%, w/w) to the soil stimulated rhizosphere microorganisms (ATP, 410%), N2 fixation (nitrogenase activity, 392%), and also plant growth (plant dry weight, 176%; total N content, 149%). Simultaneous Azospirillum inoculation and straw amendment exerted the most favourable conditions for N2 fixation on roots (nitrogenase activity, 554% increase over control) leading to the greatest biological (numbers of azospirilla, 156-fold; ATP, 543%; nitrogenase activity 554%), as well as agronomic (total dry weight, 343%; total N content, 196%; leaf surface, 478%) effects. Under farming conditions of Egypt, field-grown plants benefitted from inoculation with Azospirillum sp. Increases up to 150–170%, 180–270%, and 120–130% were reported for straw yield, grain yield, and total N, respectively. Three cultivars responded differently to inoculation, and application of 200 kg N Ha−1 significantly reduced nitrogenase activity.
Effects of Azospirillum inoculation on root infection and nitrogen incorporation in wheat
Authors: Baldani Vera L. D. , Baldani José Ivo , Döbereiner Johanna
Published: May 2010

In two field experiments, wheat was inoculated with various strains of Azospirillum spp. The two A. brasilense nir− strains isolated from surface-sterilized wheat roots increased the number of Azospirillum in surface-sterilized roots, plant dry matter, and percent N. The total N accumulated in plant tops at heading stage was increased by 30% in the first experiment (strain Sp 107 st) and by 51 and 89% (strains Sp 107 st and Sp 245, respectively) in the second experiment. The Azospirillum numbers (MPN) in chloramine-t treated roots were correlated with total nitrogen accumulation in plant tops (r = 0.92**). Numbers of Azospirillum in nonsterilized roots did not correlate with total plant N accumulation.
Effect of L-methionine-DL-sulfoximine on acetylene reduction and vesicle formation in derepressed cultures of Frankia strain D11
Authors: Gauthier D. L.
Published: May 2010

L-Methionine-DL-sulfoximine, a glutamate analog known to inhibit glutamine synthetase (GS) and glutamate synthase (GOGAT), allowed nitrogenase biosynthesis by Frankia strain D11 in presence of NH4+. GS activity, detected in cell-free extracts of D11, was higher in N2-fixing than in nonfixing conditions. These facts suggested that nitrogenase biosynthesis in Frankia was probably regulated by GS, GOGAT, or a product of their reaction, but regulation of GS by an adenylylation–unadenylylation system was probably not involved. Similarities between Frankia and Anabaena cylindrica were stressed.
The use of the 15N isotope dilution technique to estimate the contribution of associated biological nitrogen fixation to the nitrogen nutrition of Paspalum notatum cv. batatais
Authors: Boddey Robert M. , Chalk Phillip M. , Victoria Reynaldo L. , Matsui Eiichi , Döbereiner Johanna
Published: May 2010

This paper reports the results of a field experiment to investigate the use of the 15N-dilution technique to measure the contribution of biological N2 fixation to the N nutrition of the batatais cultivar of Paspalum notatum. The pensacola cultivar of this grass supports little associated N2 fixation as evidenced by the low associated C2H2 reduction activity and was thus used as a nonfixing control plant. The grasses were grown in 60-cm diameter concrete cylinders sunk into the soil, and the effects of four different addition rates of labelled nitrogen (NH4)2SO4, were investigated. The data from seven harvests clearly demonstrated that there was a significant input of plant associated N2 fixation to the nutrition of the batatais cultivar amounting to approximately 20 kg N∙ha−1∙year−1. Problems associated with the conduct of such isotope dilution experiments are discussed including the importance of using nonfixing control plants of similar growth habit, the advantages and disadvantages of growing the plants in cylinders as opposed to field plots, and the various methods of application of labelled N fertilizer.
The methodology of measurement of N2 fixation by nonlegumes as inferred from field experiments with legumes
Authors: Fried M. , Danso S. K. A. , Zapata F.
Published: May 2010

Results of field experiments using partial substratum labelling techniques are presented. These show that inorganic 15N application to soil just prior to sowing, the addition of 15N together with sucrose, incorporation of a 15N-labelled plant material into soil, as well as the 15N remaining in soil following the application of inorganic fertilizer to a previous crop provided adequate levels of 15N for field experiments to estimate N2 fixation in soybean and faba beans. These methods may be suitable for quantifying associative N2 fixation, especially if the experimental variability is low, or where N2 fixation is high. Proper site selection is therefore important. Under the conditions of the experiments reported in this paper, however, the sensitivity of detection of N2 fixation was low and could not estimate N2 fixed in plants in which the percentage of N derived from fixation was below 10–15%. The selection of the appropriate reference on standard, i.e., non-N2-fixing, crop and its judicious use in field experiments is crucial to the methodology for quantitatively measuring the amount of N2 fixed by the above methods. The most important factors in the selection of reference crops are absence of N2-fixing activity, similarity in feeding or rooting pattern of the non-N2-fixing and fixing crop, comparable growth period for reference and fixing crop, relative effect of environment on the two crops, and cropping pattern employed. In associative N2 fixation studies, an uninoculated plant in soil devoid of associative N2-fixing microorganisms would provide an ideal reference crop for an inoculated plant.
Ultrastructural investigation of 12 Methanosarcinae and related species grown on methanol for occurrence of polyphosphatelike inclusions
Authors: Scherer P. A. , Bochem H. -P.
Published: May 2010

A comparative investigation by electron microscopy of 12 strains and species belonging to the Methanosarcinaceae family of methanogenic bacteria revealed the existence of polyphosphatelike bodies during growth on methanol in an optimized medium. The Methanosarcina barkeri strains Fusaro, 227, and Wiesmoor, and M. vacuolata were found to contain smoothly marginated, polyphosphatelike inclusions. They were identified by a positive Neisser stain, by the absence of a boundary membrane, and by X-ray microanalysis in situ. They had a diameter of 0.15–0.25 µm and contained the elements Ca, P, and Fe, and sometimes Mg, S, and Cl. In addition to the polyphosphatelike bodies, coarse-looking electron-dense "granula" were observed in the cytoplasm of most of the strains. They had an average diameter of 30 nm and the same elemental composition as the polyphosphatelike bodies. As demonstrated for M. barkeri Fusaro, the "granula" were also present in cells grown in acetate and H2–CO2.
Collaborative study of the MPN, Anderson–Baird-Parker direct plating, and hydrophobic grid-membrane filter methods for the enumeration of Escherichia coli biotype I in foods
Authors: Sharpe A. N. , Rayman M. K. , Burgener D. M. , Conley D. , Loit A. , Milling M. , Peterkin P. I. , Purvis U. , Malcolm S.
Published: May 2010

Five Health Protection Branch laboratories compared two membrane filter methods (the Anderson–Baird-Parker direct plating, and a hydrophobic grid-membrane filter method) against the most probable number procedure (MPN) for enumerating Escherichia coli biotype I in foods. Results were available in 24 h by both membrane filter methods, compared with 10–14 days by the MPN procedure. For ground beef, Parmesan cheese, and cut green beans, the hydrophobic grid method generally gave the highest recovery, although the two membrane filter methods were not significantly different. Both these methods gave significantly higher recoveries than the MPN procedure, and for most foods, either method would be preferable. Further work is required before either membrane filter method can be recommended for bean and alfalfa sprouts, which may contain very high levels of Klebsiella spp.
Isolation and identification of nitrogen-fixing Enterobacter cloacae and Klebsiella planticola associated with rice plants
Authors: Ladha J. K. , Barraquio W. L. , Watanabe I.
Published: May 2010

Acid- and gas-producing nitrogen-fixing bacteria associated with rice roots and leaf sheaths were isolated. These isolates along with reference enterobacteria strains were characterized biochemically and serologically. Using selected cultural and biochemical tests, all isolates from rice were identified as Enterobacter cloacae, except two strains which were found similar to Klebsiella pneumoniae. However, further biochemical tests showed that the Klebsiella isolates were K. planticola. Antisera and fluorescent antibodies (FA) were prepared against K. pneumoniae M5a1, K. planticola DWUL2, and E. cloacae EnSs. The results of FA cross-reactions of 28 strains isolated from rice plants and of other type cultures showed a separation into two different serogroups: E. cloacae and K. planticola. However, the cross-reactions in gel immunodiffusion were found to be extensive and widespread. All strains of Enterobacteriaceae tested produced at least one immunodiffusible precipitin band with any one or all antisera. The population of N2-fixing enterobacteria associated with the root and stem of rice fell within the range of 103 and 105 per gram dry weight. The percentage incidence of N2-fixing enterobacteria among the aerobic heterotrophic bacteria in the root and stem was found to be less than 1%.
Growth responses of Neisseria gonorrhoeae auxotypes to required amino acids and bases in liquid medium
Authors: Hendry A. T.
Published: May 2010

Neisseria gonorrhoeae strains can be grouped or differentiated (auxotyped) by their requirements for none, or any one or more of proline, uracil, hypoxanthine, and citrulline or ornithine. Most strains were readily assessed because they responded with growth or no growth on each defined auxanographic medium. Other strains gave indeterminate responses on agar and the reasons were not obvious. Liquid growth studies for quantifying the usual responses showed that yields of appropriate N. gonorrhoeae auxotrophs were proportional to replacement concentrations of any one of these amino acids or bases, of methionine, or of cysteine plus cystine. This type of response, where log growth rates and lag times were unaffected, is proposed as the basis for defining (simple) auxotrophy in gonococci. The formula of the defined medium was improved by increasing proline, uracil, and hypoxanthine beyond limiting concentrations, and decreasing citrulline or ornithine, and cysteine plus cystine. Fatty acid – free bovine albumin was used to ensure homogeneous growth in liquid media. In agar, it was superior to starch for the nonnutritive protective effect required by many strains.
Pichia pseudocactophila, a new species of yeast occurring in necrotic tissue of columnar cacti in the North American Sonoran Desert
Authors: Holzschu Donald L. , Phaff Herman J. , Tredick Joanne , Hedgecock Dennis
Published: May 2010

A description is given of Pichia pseudocactophila, a new species of yeast which is closely related to Pichia cactophila. Pichia pseudocactophila is heterothallic and produces four-spored asci, whereas P. cactophila is homothallic and its asci contain a maximum of two spores. Their morphological and physiological properties and G + C contents of their nuclear deoxyribonucleic acids (DNAs) are similar, but the DNA of P. pseudocactophila shows only 35% homology with the DNA of P. cactophila. In addition, strains of P. pseudocactophila have electrophoretic enzyme patterns for glucose-6-phosphate dehydrogenase, hexokinase-1, hexokinase-2, and phosphoglucomutase that allow them to be distinguished from P. cactophila strains. Lastly, P. pseudocactophila has been found only in rotting tissue of columnar cacti (Pachycereus pringlei and close relatives) in Mexico and southern Arizona, whereas P. cactophila is a host-plant generalist and is distributed worldwide in all cactus species so far investigated.
Hydrogen cyanide production by Pseudomonas aeruginosa at reduced oxygen levels
Authors: Castric Peter A.
Published: May 2010

Hydrogen cyanide production by Pseudomonas aeruginosa growing in a synthetic medium required aerobosis but operated efficiently at low dissolved oxygen concentration. Half maximum levels of cyanogenesis occurred at 0.015 μM oxygen; maximum cyanogenesis occurred over a wide range, 0.1–180 μM, of oxygen concentrations. These cells lost the ability to produce cyanide upon aerobic incubation in the absence of both the carbon energy source (L-glutamate) and the metabolic precursor of hydrogen cyanide (glycine). This loss of cyanogenesis was dependent on oxygen concentration; 1.0 μM oxygen produced no detectable loss, whereas 180 μM oxygen caused a rapid decline in cyanogenic ability. The endogenous cyanide production rate of cells in the presence of carbon energy source was not significantly influenced by oxygen concentration. During the batch culture cycle, the acquisition of the ability to produce HCN was preceded by oxygen reduction to growth-limiting levels. Cells which had lost the ability to produce hydrogen cyanide by oxygen treatment required protein synthesis before they could again become cyanogenic.
Effects of chetomin on growth and acidic fermentation products of rumen bacteria
Authors: Jen W.-C. , Jones G. A.
Published: May 2010

Chetomin, an antibiotic metabolite of Chaetomium spp., was tested in the form of its tetrathiol derivative for its effects on growth and carbohydrate metabolism by five strains of functionally important rumen bacteria. The compound was bacteriostatic for the strains tested and Gram-positive bacteria were more sensitive to inhibition than Gram-negative bacteria. In an anaerobic broth dilution assay using a medium lacking rumen fluid, the minimum inhibitory concentration (MIC) of chetomin which completely inhibited growth of Butyrivibrio fibrisolvens D1 for 18 h at 39 °C was 40 μg∙mL−1. The MICs determined under the same conditions for Megasphaera elsdenii B159, Selenomonas ruminantium GA192, and Succinivibrio dextrinosolvens 24 were 160, 600, and 60 μg∙mL−1, respectively. The MIC for cellulose hydrolysis by Ruminococcus albus 7 was 20 μg∙mL−1. Chetomin at concentrations below the MIC appeared to inhibit the separation and division of cells in cultures of B. fibrisolvens D1. Chetomin consistently stimulated acetate production from glucose by B. fibrisolvens D1, M. elsdenii B159, and S. ruminantium GA192 at the expense of compounds which comprised major soluble end products of fermentation in cultures lacking chetomin.
Cell division in Deinococcus radiodurans and a method for displaying septa
Authors: Murray R. G. E. , Hall M. , Thompson B. G.
Published: May 2010

The study of sections, freeze-cleaved, and whole-cell preparations of Deinococcus radiodurans supported the contention that septa close assymmetrically and originate from discrete opposing locations on the cell surface. Tetrads and the larger associations (sheets) of cells in some strains were formed by alternate and synchronized divisions in two planes. The polarity initiating the second division in cells of the Sark strain, in particular, was often expressed in slower growing cells before completion of the first division so that the advancing margins of the first septum were diverted towards the nearest new pole; the resulting gap was closed later on, and consequently, the cell compartments of this coccus were in communication for some time after two rounds of nuclear segregation. Freeze cleaving showed that the initial generation of septa involved a short sulcus in the plasma membrane and not a circumferential infolding. The shape and form of the developing septum was inferred from sections but was displayed in whole-cell preparations by a technique which selectively and positively stained a septal component. Positive staining of the septum with uranyl salts was appreciable when the relative stainability of the peripheral wall (mainly peptidoglycan) was reduced by pretreatment with salts of low atomic weight metals (0.01–1.0%, w/v) such as cobalt, copper, iron, or zinc. Examination of these whole-cell preparations by stereoscopy showed that the septal diaphragm closes as a slit or long oval, and the advancing margin shows curvature towards the next axis of division. The mechanism and exact site of this positive staining was not elucidated; vancomycin blocking of the uncross-linked peptides of peptidogylcan was almost as effective as the transition metal salts as a foretreatment for staining septa.
Cell wall proteins of Candida albicans
Authors: Chaffin W. LaJean , Stocco Douglas M.
Published: May 2010

Proteins were solubilized from cell wall fractions of Candida albicans and separated by polyacrylamide gel electrophoresis. Cell walls were isolated from 25 and 37 °C growing and stationary phase yeast cultures and from germ tubes. The 42 protein bands detected by dye binding were observed in all wall extracts, regardless of the temperature, growth state, or morphology of the culture. The carbohydrate content of most bands was below the detectable limit of the periodic acid Schiff reagent. The protein complement revealed by autoradiography of radiolabeled proteins was half that detected by staining. Two bands showed greater intensity from cultures grown at 37 °C. The radio-labeled pattern was similar with both [35S]methionine- and [14C]leucine-labeled proteins and either pulse- or continuous-labeled proteins.
The occurrence of killer characters in yeasts
Authors: Rosini Gianfranco
Published: May 2010

Strains of the genera Saccharomyces, Saccharomycodes, Schizosaccharomyces, Hanseniaspora, Kluyveromyces, Pichia, Kloeckera, and Torulopsis were examined for killer, sensitive, neutral, and killer–sensitive characteristics against a killer strain (NCYC738) and a sensitive strain (NYCC1006) of Saccharomyces cerevisiae. Thirty-one Saccharomyces cerevisiae strains out of 782 screened were able to kill the sensitive test strain; 707 appeared to be sensitive and 44 neutral. A high frequency of killer phenotypes (71.4%) was found in Hansenula anomala var. anomala strains. No killer strains were present in the remaining 17 species considered.
Factors affecting the irreversible attachment of Pseudomonas aeruginosa to stainless steel
Authors: Stanley Patricia M.
Published: May 2010

To better understand the interaction between bacteria and surfaces, we studied the irreversible attachment of Pseudomonas aeruginosa to a common surfacing material. When brought into contact with the steel, cells began to attach in less than 1 min and the number adhering increased with time. An important physiological variable in attachment was cell motility since adherence decreased at least 90% when flagella were removed by blending. This treatment was shown to be effective because it caused motility loss and not because it removed a structure necessary for adherence. Cell viability was less important since adherence decreased only 50% when the number of viable cells was reduced 4.7 logs by heating or formaldehyde treatment. Significant environmental variables included turbulence and ionic strength. Attachment of motile cells was reduced 90% by agitation, although agitation had little effect on adherence of nonmotile cells. Both motile and nonmotile cells adhered poorly in distilled water with attachment increasing as CaCl2 or NaCl concentration increased to 10 mM. At 100 mM, attachment decreased. Viable cells, both motile and nonmotile, adhered best at a pH of 7 to 8, whereas nonviable cells attached most rapidly at a low pH.
Moderately large plasmids of Rhizobium meliloti
Authors: Adachi T. , Hooper I. , Iyer V. N.
Published: May 2010

Each of four wild-type isolates of Rhizobium meliloti carried single moderately large (100–200 megadaltons) plasmids in addition to their megaplasmids. Such moderately large plasmids from these strains had either considerable or little sequence homology to one another. Sequence homology was not correlated to the geographical origin of the strains. In one selected strain where this was examined, loss of the moderately large plasmid did not reduce the nodulating or nitrogen-fixing ability of the strain in laboratory experiments. In this strain, the moderately large plasmid was found to be selftransmissible by mating between R. meliloti.
The effect of sublethal heating on sclerotia of Selerotium rolfsii
Authors: Lifshitz R. , Tabachnik M. , Katan J. , Chet I.
Published: May 2010

Sublethal heating of sclerotia of Sclerotium rolfsii at 50 °C for 30 min increased leakage of 14C-labelled water-soluble organic compounds from the sclerotia, and increased their colonization by bacteria and streptomycetes 574- and 1420-fold, respectively. Disease incidence in bean plants inoculated with heat-treated sclerotia was 43% less than disease incidence produced by unhealed ones. Scanning electron microscope observations demonstrated that heating increased the frequency of surface cracks on the sclerotia and the concentrations of bacteria on or around these cracks about 10 times.
Variation in ability of Rhizobium leguminosarum isolates to fix dinitrogen symbiotically in the presence of ammonium nitrate
Authors: Nelson Louise M.
Published: May 2010

To assess the variation in symbiotic effectiveness of N2-fixing Rhizobium leguminosarum isolates in the presence of NH4NO3, peas were inoculated with 38 isolates and grown for 4 weeks with weekly additions of 2 mM NH4NO3. Acetylene reduction was inhibited relative to a N-free control in all isolates but the inhibition varied from 60 to 100%. There were also significant differences (p = 0.05) between isolates with varying inhibition of C2H2 reduction in H2 uptake, H2 evolution, and leghemoglobin content. Ten isolates were selected for further study of the importance of NH4NO3 concentration (0, 1,2, and 5 mM) and plant growth stage (3,4, and 5 weeks) to characters associated with N2 fixation and plant growth. Plant age, NH4NO3 treatment, and isolate were all significant sources of variation (p ≤ 0.01) for each character measured but interactions between these factors were also significant. There were significant differences between isolates in the rate of decrease in C2H2 reduction with increasing NH4NO3 concentration (C2H2 reduction responsiveness to NH4NO3) and this responsiveness term was correlated with C2H2 reduction rates at 2 and 5 mM NH4NO3 (p = 0.01). Acetylene reduction rates were correlated with shoot dry weights at 0.1, and 2 mM NH4NO3 (p = 0.001). These results suggest the possibility of enhancing N2 fixation in peas through selection of rhizobia with maximum effectiveness at low levels of combined nitrogen.
A multiple extraction–centrifugation method for the recovery of viruses from waste water treatment plant effluents and sludges
Authors: Lewis Margaret A. , Nath Michael W. , Johnson J. C.
Published: May 2010

Absorption of 14C-labelled poliovirus-2 to sedimentable solids of primary sludge samples collected from a secondary treatment facility during a 6-month period averaged 94%; for anaerobically digested sludge, 99%. The extent of virus adsorption was influenced by the amount of solids. Maximal adsorption occurred at or above 0.5% solids with sludge diluted with deionized water and above 1.5% solids when diluted with the respective particle-free sludge supernatants. A Tris–HCl buffer containing NaCl, glycerol, and serum was found to efficiently elute poliovirus-2 from primary sludge solids. By means of re-extraction and concentration by centrifugation (the TEC procedure), the average recoveries of poliovirus-2 were 92–94% based upon either infectivity or radioactivity analyses. Similarly, recoveries were 90–92% for poliovirus-2 in digested sludge. Maximum elution was dependent upon all four TEC buffer components and the restriction of solids to≤ 1.0%. The procedure was found to be more efficient than glycine–NaOH and Freon procedures or elution with beef embryo extract. As adapted for effluents the procedure increased the yield and improved the consistency of virus recovery. The arithmetic mean titers obtained during a monitoring study for primary and digested sludge were 4.2 × 105 and 5.1 × 103 plaque-forming units (pfu)/L; for primary, secondary, and final effluents 2.3 × 105, 4.7 × 103, and 4.7 × 102 pfu/L, respectively.
The influence of high temperatures on the growth and survival of Rhizobium spp. in peat inoculants during preparation, storage, and distribution
Authors: Somasegaran P. , Reyes V. G. , Hoben H. J.
Published: May 2010

Gamma-irradiated peat was used to prepare inoculants for 10 different species of tropical legumes. These inoculants were sent to cooperators in 14 cities in 13 tropical countries. Each cooperator received a package containing a maximum recording thermometer, plating-media components, special instruction sheets, and inoculants. Control experiments were pursued in the laboratory by exposing the various inoculants to 28, 37, and 46 °C. Temperatures reached in the inoculants during their transportation varied from 26 (Mexico) to 45 °C (Kenya). Arrival time of the inoculants ranged from 6 days (Hissar, India) to 54 days (St. Augustine, West Indies). Although a total loss of viability was reported for the chick-pea inoculant (Saudia Arabia) and a severe decrease in two others (bean and lentil inoculants in Kenya and Saudi Arabia, respectively), over 90% of the inoculants received had viable counts in excess of 1 × 108 cells per gram of moist peat. Laboratory data indicated that 28 °C was optimal for multiplication to maximal numbers in excess of 1 × 1010 cells per gram of moist peat. Six inoculants studied for long-term storage showed excellent quality for 24 weeks at 28 °C. At 37 °C the cell multiplication was comparable with that at 28 °C with 8 of the 10 strains only during the 1st week. For all strains, 46 °C was lethal. Large reductions in viable counts were observed during inoculant preparation when broth cultures were added to peat.
Protoplast release from fungi capable of steroid transformation
Authors: Długoński J. , Sedlaczek L. , Jaworski A.
Published: May 2010

Protoplasts were obtained from Hyphoderma roseum (Fries) and Cunninghamella elegans (Lendner), fungi capable of steroid 11-hydroxylation. The lytic enzyme preparation was derived from Trichoderma viride CBS 354-33. Homogeneous protoplast suspension, free of mycelial debris and cell wall fragments, transformed cortexolone and 6α-fluorocortexolone-16,17-acetonide to the same products as the intact mycelium of the microorganisms. Liberation of protoplasts and their stabilizaiton during steroid transformation was the most effective in 0.8 M MgSO4; still, this compound impaired steroid hydroxylation. Consequently, the concentration of the transformation product formed was nearly the same as in sucrose, mannitol, and sorbitol, compounds which caused no inhibition but which were less effective stabilizers.
Ecological distribution of Legionellaceae in the Quebec city area
Authors: Joly Jean R. , Boissinot Maurice , Duchaine Jean , Duval Marie , Rafrafi Jamel , Ramsay Danielle , Letarte Robert
Published: May 2010

One hundred environmental water samples, which were collected in the Quebec city area and cultured on buffered charcoal yeast extract medium and three selective media, were inoculated to guinea pigs and were screened by direct immunofluorescent staining (DFA) for the presence of Legionellaceae. Six isolates were made (four Legionella pneumophila and two Tatlockia (Legionella) micdadei: three by animal inoculation and three by culture). No samples were simultaneously positive by both methods. After screening by DFA, 43 of the 100 samples were positive for Legionellaceae and 27 of those contained more than one serogroup and (or) species of Legionellaceae. Legionella pneumophila (serogroups 1 to 6) was the most frequent species seen by DFA. These results clearly show that Legionellaceae are frequent members of the freshwater microbial flora of the Quebec city area.
Genetics of Aspergillus flavus: linkage of aflatoxin mutants
Authors: Papa K. E.
Published: May 2010

Eight aflatoxin (afl) mutants of Aspergillus flavus were induced with N-methyl-N′-nitro-N-nitrosoguanidine. Heterozygous diploids formed between afl mutants and tester strains revealed that each afl mutant was recessive. Haploids selected from these heterozygous diploids indicated the linkage of all eight afl mutants to markers on group VII. These include previously mapped arg-7 (arginine), leu (leucine), dominant afl-1, and nor which accumulates norsolorinic acid that is visible as an orange–red pigment. Diploid complementation tests indicated that all but two afl mutants were nonallelic. Diploids homozygous for nor, resulting from crossing-over, were isolated and used to map new afl genes.
In vivo protection of penicillin-susceptible Bacteroides melaninogenicus from penicillin by facultative bacteria which produce beta-lactamase
Authors: Brook Itzhak , Pazzaglia Garry , Coolbaugh James C. , Walker Richard I.
Published: May 2010

We investigated the possibility that beta-lactamase producing strains of Klebsiella pneumoniae and Staphylococcus aureus can protect organisms of the Bacteroides melaninogenicus group from penicillin. A mixed infection was induced in mice in the form of a subcutaneous abscess involving a penicillin-susceptible encapsulated B. melaninogenicus, and a beta-lactamase producing strain of either K. pneumoniae or S. aureus. The infected animals were treated for 7 days with single or combined antimicrobial therapy. The single agents used were penicillin, clavulanic acid, metronidazole, and gentamicin. The antimicrobial combinations were penicillin and clavulanic acid, penicillin and gentamicin, and metronidazole and gentamicin. Administration of a single agent was effective in treating abscesses caused by susceptible organisms. The only effective therapy for mixed infections was by combination therapy of penicillin and clavulanic acid or metronidazole and gentamicin. This study supports the hypothesis that beta-lactamase producing facultative bacteria may shield their anaerobic counterparts from penicillin therapy, thereby contributing to the persistence of the infection.