bluuebunny/crossref_metadata_2025 huggingface dataset:
The intracellular Na+ and K+ composition of the moderately halophilic bacterium, Paracoccus halodenitrificans
Authors: Sadler M. , McAninch M. , Alico R. , Hochstein L. I.
Published: May 2010

The intracellular concentrations of Na+ and K+ in exponentially growing Paracoccus halodenitrificans were independent of the NaCl concentration of the growth medium. The observed values were approximately 100 and 300 mM for Na+ and K+, respectively. In stationary phase cells, the ultimate values for Na+ depended on the NaCl concentration of the growth medium. With cells grown in the presence of 1 M NaCl, the value was about 500 mM; for cells grown in the presence of 3 M NaCl, the value was about 1.1 M. The K+ concentration in stationary phase cells was unaffected by the NaCl concentration in the growth medium. The final value was about 100 mM. Associated with these changes were changes in the ATP pool and decreases in the activities of the NADH oxidase system and the membrane-bound ATPase. It is proposed that the decrease in the activities of these enzymes may account for the ion flows observed in stationary phase cells.
Modified Christie–Atkins–Munch-Petersen (CAMP) test for direct identification of hemolytic and nonhemolytic group B streptococci on primary plating
Authors: Bae Ben H. C. , Bottone Edward J.
Published: May 2010

A primary plating medium, using sheep blood agar with preformed zones of cell-free staphylococcal β-hemolysin, was used for direct identification of both hemolytic and nonhemolytic group B streptococci by the direct elicitation of the Christie–Atkins–Munch-Petersen (CAMP) reaction. A positive CAMP reaction consisted of a semilunar-shaped area or circle of complete hemolysis of sheep erythrocytes and occurred only when colonies of group B streptococci developed along the periphery of the preformed zone of staphylococcal β-hemolysin. Of 104 simulated specimens containing group B streptococci in combination with a variety of microbial species and of 85 vaginal specimens examined, direct recognition of group B streptococci was possible in 64 (61.5%) simulated specimens and in 12 (100%) vaginal cultures. Group B streptococcal colonies not developing along the active edge of staphylococcal β-hemolysin were still identified by subculture. Of particular value was the facilitated recognition of colonies of nonhemolytic group B streptococcal strains and of hemolytic group B streptococci few in number or overgrown by other microbial species.
Sensitivity of Rhizobium to selected isoflavonoids
Authors: Pankhurst C. E. , Biggs D. R.
Published: May 2010

Eleven isoflavonoids were tested in both soft agar and liquid media for inhibitory activity against eight Rhizobium strains. Results of the two bioassays showed that pisatin, coumestrol, biochanin A, formononetin, genistein, rotenone, and vestitol lacked significant inhibitory activity. Phaseollin and maackiain were moderately inhibitory (ED50 (mean effective dose) = 30–100 μg/mL), and medicarpin and kievitone were strongly inhibitory (ED50 = 10–60 μg/mL) towards slow-growing R. japonicum and R. lupini and also towards two fast-growing Lotus rhizobia. In contrast, R. trifolii, R. leguminosarum, and R. phaseoli were not affected by these compounds (ED50 > 100 μg/mL), and R. meliloti was inhibited only by kievitone (ED50 = 30–60 μg/mL). At a concentration of 100 μg/mL, medicarpin and kievitone were found to be bactericidal to R. japonicum, R. lupini, and the fast-growing Lotus rhizobia.
Detection of endotoxin in ear specimens from patients with chronic otitis media by means of the limulus amebocyte lysate test
Authors: Bernstein Joel M. , Praino Martin D. , Neter Erwin
Published: May 2010

The limulus amebocyte lysate (LAL) test is the most sensitive procedure for the detection of endotoxic lipopolysaccharides. The test was applied to middle ear fluids, cholesteatomas, and granulation tissue specimens from 31 patients in parallel with bactériologic examination. The LAL test and bacteriologic examination yielded concordant results with 26 out of 28 specimens. A positive LAL test was obtained with 11 specimens containing endotoxin-producing organisms. The test became positive within 60 min of incubation in 10 out of 11 specimens and in 1 specimen between 1 and 24 h, suggesting that, in the majority of specimens, endotoxin was present in the specimen itself and that the result was not due to the in vitro multiplication of the microorganisms. All negative tests remained negative for 24 h. It is conceivable that endotoxin present in ear fluids may contribute to the pathologic changes in chronic otitis media.
Unusual polar lipids of Micrococcus radiodurans strain Sark
Authors: Thompson B. G. , Anderson R. , Murray R. G. E.
Published: May 2010

The polar lipids of Micrococcus radiodurans strain Sark appear to be unique in that common bacterial phospholipids such as phosphatidylethanolamine, phosphatidylserine, phosphatidylcholine, and phosphatidylinositol are absent. Of the 13 polar lipids detected, 5 contain phosphorus and carbohydrate, 4 contain carbohydrate and no phosphorus, and 1 contains phosphorus as well as sulfur. None of the polar lipids contain free choline or amino groups and none are sensitive to phospholipases C or D. Of eight selected polar lipids tested, all were found to be labile to mild alkali, suggesting the presence of ester linkages. It is suggested that the unusual lipid profile of M. radiodurans strain Sark may be useful in taxonomic considerations.
Isolation and characterization of guanine auxotrophs in Neurospora crassa
Authors: Greer W. L. , Wellman A. M.
Published: May 2010

An ad-9 strain of Neurospora crassa was mutagenized with ethylmethane sulfonate (5%) and selected for guanine auxotrophy. The resultant double adenine plus guanine mutant was backcrossed with wild type and a single guanine auxotroph was isolated from the progeny. In vitro assays indicated that the mutant had GMP synthetase activity comparable with wild type, but was completely lacking in IMP dehydrogenase activity. The guanine requirement can therefore be explained by the mutant's inability to convert IMP to XMP. Another guanosine auxotroph was able to adapt and grow on minimal medium after 3 days. This mutant had GMP synthetase activity comparable with wild type but had only 10% of the IMP dehydrogenase activity of wild type, which may possibly explain its ability to grow on minimal medium after 3 days. It was confirmed that the two isolates are not allelic by crossing the two and recovering 25% wild-type progeny. Our isolate must therefore be designated gua-2.
Influence of sodium nitrite, temperature, and lactic acid bacteria on the growth of Brochothrix thermosphacta under anaerobic conditions
Authors: Collins-Thompson D. L. , Lopez G. Rodriguez
Published: May 2010

In commercial vacuum-packed bologna, growth of Brochothrix thermosphacta was limited at 5 °C during a 4-week storage period. Factors controlling the growth of this organism were associated in part with certain lactobacilli isolated from the meat. The lactic acid bacteria associated with the decline of B. thermosphacta and overall spoilage of vacuum-packed bologna were isolated and identified. The principal organisms were Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus plantarum, Lactobacillus viridescens, Leuconostoc mesenteroides, and certain streptococci. In associated growth experiments with B. thermosphacta at 5 and 15 °C, L. brevis and L. plantarum showed the greatest antagonism towards the Brochothrix species. Studies with changes in incubation temperatures (5 or 15 °C) or nitrite levels (0–50 μg/mL) indicated that these two factors influence the antagonism but were minorcompared with the influence of the lactic acid bacteria.
Chemical and serological properties of a cyanogen bromide peptide of southern bean mosaic virus protein
Authors: Tremaine J. H. , Ronald W. P. , Kelly E. M.
Published: May 2010

Southern bean mosaic virus (SBMV) protein was cleaved with cyanogen bromide and a highly basic peptide, CB-1, was isolated by ion exclusion and ion-exchange chromatography. Twelve peptides were separated from a tryptic digest of CB-1 by ion-exchange chromatography and the composition of these peptides was similar to that of peptides released from EDTA-swollen virus particles by limited tryptic digestion. The composition and N-termini of the tryptic peptides indicated CB-1 was from the N-terminus of SBMV protein and contained 48 amino acid residues. The CB-1 peptide moved rapidly to the cathode in polyacrylamide gel electrophoresis at pH 3.9 and contained nine arginine residues, three lysine residues, and no acidic amino acid residues. It was shown to interact with purified viral RNA, sodium dextran sulfate, and calf thymus DNA.Antiserum to sodium dodecyl sulfate (SDS)-dissociated virus gave a reaction of partial identity between the CB-1 peptide and the SDS-dissociated virus in SDS gel diffusion tests. The CB-1 peptide did not react with antiserum to SDS-dissociated, trypsin-treated virus. Gel diffusion tests conducted in saline agar gels between trypsin-treated virus and SBMV, with SBMV antiserum, did not show differences in their serological properties. Antiserum to the CB-1 peptide conjugated to tomato bushy stunt virus reacted with SBMV but SBMV antiserum did not react with CB-1 or the CB-1-tomato bushy stunt virus conjugate.
Differences in the biochemical compositions and elicitor activity of extracellular components produced by three races of a fungal plant pathogen, Colletotrichum lindemuthianum
Authors: Anderson Aaanne J.
Published: May 2010

High molecular weight products from the α, β, and γ races of Colletotrichum lin-differed in their carbohydrate and protein compositions and in their abilities to elicit symptoms of a hypersensitive response in dark red kidney bean. The neutral sugar composition of the products varied in their proportions of rhamnose, mannose, galactose, and glucose. Polyacrylamide gel electrophoresis showed the protein components to be more numerous in the β race products than in the α or γ race products. Each protein band co-stained for carbohydrate. Highest elicitor activity was observed in the products from the α race, a race avirulent on dark red kidney. The products from the weakly virulent γ race were about 10-fold less active as elicitors than those of the α race. With the β race, a race highly virulent on dark red kidney, elicitor activity was 100-fold less than that of the α race.
The effect of substrate on inhibition of Corynebacterium lepus by isonicotinic acid hydrazide (Isoniazid)
Authors: Gerson D. F. , Cooper D. G. , Ramsay B. , Zajic J. E.
Published: May 2010

Isonicotinic acid hydrazide (INH) inhibits the growth of Corynebacterium lepus on hexadecane but has no effect on its growth on fructose. INH also inhibits the production of the mycolic acid containing lipopeptide bioemulsifier normally produced by C. lepus in response to an insoluble substrate. The primary effect of INH appears to be inhibition of mycolic acid synthesis, which limits the growth of C. lepus on hexadecane by reducing the concentration of bioemulsifier.
Chemicals which promote survival of ultraviolet-irradiated lon and ruv mutants of Escherichia coli K12
Authors: Kato Yasuhiko , shiraki Shuichi , Hamada Yoshimasa , Iyehara-Ogawa Hiroaki , Nakayama Hiroaki
Published: May 2010

The effects of postirradiation incubation with various chemicals structurally related to pantolactone on the survival of ultraviolet-irradiated Escherichia coli lon and ruv mutants were examined. Certain cyclic compounds with a butyrolactone, tetrahydrofuran, furan, tetrahydropyran, or 2-pyron ring showed substantial rescue activity in lon and (or) ruv mutants. In addition, several aliphatic, monocarboxylic acid salts, including hydrolysis products from pantolactone and butyrolactone, were also active in one or both of these mutants, especially pantoate and other hydroxy acid salts in the ruv bacterium. The two mutants differed considerably in their susceptibility spectra for the rescue actions of these compounds.
The influence of temperature on the growth inhibitory effect of carbon dioxide on Pseudomonas fragi and Bacillus cereus
Authors: Enfors Sven-Olof , Molin Göran
Published: May 2010

The growth inhibitory effect of 50 kPa (0.5 atm) CO2 was tested for Pseudomonas fragi in the temperature range 5–35 °C and of 101 kPa (1 atm) CO2 on Bacillus cereus in the range 18–46 °C. The maximum specific growth rate (μmax) of P. fragi in air (pH 6.7) was 0.44 h−1 at 35C, 0.66 h−1 at 30 °C, and 0.078 h−1 at 5 °C. In 50 kPa of CO2 in air the relative inhibition of the growth rate was about 30% at 35 °C, 50% at 30 °C, and 90% at 5 °C. Thus, the inhibitory effect of CO2 successively increased with decreasing temperature, an effect which was explained by the increasing solubility of CO2 with decreasing temperature. The anaerobic growth of B. cereus (101 kPa N2) was optimal at 40 °C and stopped at temperatures below 18 °C and above 46 °C. The relative inhibitory effect of 101 kPa CO2 at the optimum growth temperature was about 40%; this increased to 100% near the maximum and minimum growth temperatures. The growth inhibitory effect of reduced temperature (below optimum) and CO2 on B. cereus was larger than that expected from the increased solubility of CO2 at lower temperatures.
Inhibition of Fusarium moniliforme var. subglutinans, the causal agent of pine pitch canker, by the soil bacterium Arthrobacter sp.
Authors: Barrows-Broaddus Jane , Kerr T. J.
Published: May 2010

A species of Arthrobacter was recovered during culture of the causal organism of pitch canker of southern pines, Fusarium moniliforme var. subglutinans (FMS). Arthrobacter is a relatively common soil bacterium and is lytic to several fungal pathogens in the soil. Soil samples from two seed orchards with pitch canker and one from a healthy pine plantation all yielded Arthrobacter. These isolates were evaluated for their ability to inhibit the growth of FMS isolates from pitch canker tissue and from soil in areas with high pitch canker disease incidence, and to several other species of Fusarium isolated from the same soil samples where Arthrobacter was recovered. Generally the pitch canker isolates were more sensitive to Arthrobacter than the soil fusaria. There was variation in the ability of the Arthrobacter isolates to inhibit the growth of the fusaria recovered from the soil at the three different test sites. Light and scanning electron microscope observations revealed that hyphae of FMS growing near an isolate of Arthrobacter were enlarged, producing many vesicularlike structures. The surface of these hyphae was warped and wrinkled in comparison with normal hyphae.
Etude taxonomique d'entérobactéries appartenant ou apparentées à l'espèce Escherichia coli
Authors: Gavini F. , Izard D. , Trinel P. A. , Lefebvre B. , Leclerc H.
Published: May 2010

Phenetic (numerical analysis) and genetic (DNA–DNA hybridization) studies were carried out on strains belonging or related to the species Escherichia coli. They have shown the diversity of its phenotypes, by the presence of plasmidic characters (citrate+, urease+, H2S+, tetrathionate reductase+, raffinose+, and saccharose+). New strains related phenetically to E. coli are also individualized. They showed less than 30% DNA relatedness with E. coli. A new definition of E. coli is presented.
Microbial oxidation of gaseous hydrocarbons: production of alcohols and methyl ketones from their corresponding n-alkanes by methylotrophic bacteria
Authors: Hou Ching T. , Patel R. N. , Laskin A. I. , Marczak I. , Barnabe N.
Published: May 2010

Cell suspensions of methane-utilizing bacteria oxidized n-alkanes (propane, butane, pentane, and hexane) to their corresponding alcohols and methyl ketones. The product alcohols and methyl ketones accumulated extracellularly. Methanol-grown cells of methane-utilizing bacteria did not oxidize n-alkanes. The product primary alcohol was detected in a cell-free system but only in a trace amount in the whole cell system due to further oxidation. The optimum conditions for in vivo formation of secondary alcohol and methyl ketone from n-alkanes were compared between two distinct types of C1-utilizing microbes: Methylococcus capsulatus M1 (type I membrane) and Methylosinus trichosporium OB3b (type II membrane). The production of acetone or 2-butanone from n-alkanes ceased after 3 h of incubation for strain OB3b and 5 h for strain M1. The amount of these methyl ketones did not decline during 30 h of incubation. The optimum pH for the in vivo production of methyl ketones from n-alkanes by both strains was around 7.0. However, secondary alcohols were accumulated at higher amounts around pH 6.0. The optimum temperature for the in vivo production of methyl ketones from n-alkanes was around 40 °C for strain M1 and around 30–35 °C for strain OB3b. Higher accumulation of secondary alcohol was detected at 30–40 °C for strain M1 and 25 °C for strain OB3b.The alkane hydroxylation enzyme was located in the cell-free particulate fraction precipitated between 10 000 and 40 000 × g centrifugation. The yield of primary and secondary alcohols from n-alkane in the cell-free system was about equal. Evidence obtained indicates that the hydroxylation of n-alkanes (both terminal and subterminal oxidations) is also catalyzed by the methane hydroxylation – alkene epoxidation enzyme system.
In vitro antigonococcal activity of urogenital coagulase-negative staphylococci
Authors: Lafond L. , Bisaillon J.-G. , Saheb S. A. , Beaudet R. , Sylvestre M.
Published: May 2010

Twenty-four urogenital isolates of coagulase-negative staphylococci were selected because of their demonstrated ability to inhibit Neisseria gonorrhoeae growth in vitro. These organisms showed quantitative differences in their growth-interfering capability as revealed by a flip-flop agar overlay method. The composition of the culture medium affected the production of antigonococcal activity. Antigonococcal activity was shown with the following media: GC agar base with Lankford defined supplement, brain heart infusion agar, trypticase soy agar, and dextrose starch agar, but not with the GC agar base with CVA enrichment. An antigonococcal activity was obtained in the liquid phase prepared from semisolid agar cultures for 10 of the 24 staphylococcal isolates, whereas no activity was found in the supernatant from liquid cultures. The production of antigonococcal activity by staphylococci in vitro is influenced by growth conditions.
Dependence of extracellular chitinase activity of Serratia marcescens QMB1466 on continuous culture dilution rate
Authors: Young Manuel E. , Carroad Paul A.
Published: May 2010

The production of chitinase by Serratia marcescens QMB1466 was studied in continuous culture with N-acetylglucosamine as limiting substrate. Enzyme activity in the culture filtrate exhibited a maximum with respect to dilution rate, a phenomenon that can be explained as a balance between induction and catabolite repression.
Genetic studies of H group plasmids by bacteriophage P1 transduction
Authors: Taylor Diane E. , Levine Jessie G. , Sibay Godyne , Walter Anthony
Published: May 2010

Bacteriophage P1 transduction was used to study the incompatibility group H1 plasmid pRG1251, molecular weight 120 × 106, and the incompatibility group H2 plasmid pSD114, molecular weight 166 × 106. The order of resistance (R) determinants on pSD114 was deduced from transduction and segregation experiments to be chloramphenicol-tetracycline-kanamycin-streptomycin. Resistance to tellurium and to coliphages, which are properties also encoded by many H2 plasmids, were not transduced with the other markers. On pRG1251, the ampicillin and tetracycline resistance markers appear to be located together, as do the chloramphenicol, streptomycin, and sulfamethoxazole resistance markers. Frequently, blocks of R determinants were transposed to the P1 genome or to the Escherichia coli chromosome. P1 DNA was isolated which carried the chloramphenicol, streptomycin, and sulfamethoxazole markers from pRG1251 and had a molecular weight of 64 × 106. Other P1 prophages carried R determinants from pSD114 and had molecular weights of 86 × 106. A plasmid of molecular weight 124 × 106 was also isolated which contained incompatibility determinants from P1 (incompatibility group Y) and from the H2 group plasmid. The mechanism of formation of these unusual plasmid species is discussed.
Methanogenesis in freshwater sediments: inherent variability and effects of environmental contaminants
Authors: Pedersen D. , Sayler G. S.
Published: May 2010

Temporal and spatial variability of methanogenesis and the effects of environmental contamination on methanogenesis were examined in freshwater sediments. Temporal and spatial variation was found to be significant in uncontaminated freshwater reservoir sediments. The relative concentration of organic matter and temperature explained approximately 43% of the total variability. Known environmental contaminants marginally inhibited methanogenesis and only a coal conversion effluent and phenanthrene, 100 mg L−1, demonstrated statistically significant inhibition of methanogenesis under acute dosing conditions. Methyl viologen, a potent inhibitor of pure culture methanogenesis, inhibited sediment methanogenesis at high concentrations, i.e., 2570 mg L−1, indicating that the sediment environment protected the methanogenic population from the toxic effects of the environmental contaminants.
Growth inhibition activity and bacteriophage and bacteriocinlike particles associated with different species of Clostridium
Authors: Nieves Beatriz M. , Gil Francisco , Castillo Francisco J.
Published: May 2010

Thirty-four strains corresponding to 16 species of Clostridium were examined for growth inhibition activity and production of phage and bacteriocinlike particles. Twenty-five strains were found to inhibit growth of one or more of the other strains. The widest range of activity corresponded to C. bifermentans 18137 which inhibited growth of 23 strains. Cell-free filtrates of positive cultures were inactive with the exception of the one from C. bifermentans 18137. A wide variety of particles with diverse morphology was observed in lysates of cultures treated with mitomycin C (1 μg/mL).
Isolation and characterization of hemin-permeable, envelope-defective mutants of Salmonella typhimurium
Authors: Janzer Janice J. , Stan-Lotter Helga , Sanderson Kenneth E.
Published: May 2010

From Salmonella typhimurium LT2 hemA (δ-aminolevulinic acid requiring) 15 mutants were isolated which grew on the hydrophobic compound hemin. All had increased sensitivity to antibiotics such as vancomycin, bacitracin, novobiocin, erythromycin, rifampin, and oleandomycin, and were considered to be envelope mutants (Env−). Half the mutants were rough, based on altered bacteriophage sensitivity and deoxycholate sensitivity, whereas the remainder were smooth; three of the smooth mutants were studied in detail. They gave increased uptake of gentian violet but no increase in leakage of a periplasmic protein, RNase I. The total membranes and fractions from sucrose gradient centrifugations representing inner and outer membranes of the wild type and three mutants were examined by sodium dodecyl sulfate – polyacrylamide gel electrophoresis (SDS–PAGE) and isoelectric focussing – PAGE (IEF–PAGE). The major outer membrane proteins (molecular weights (MW)33 000, 34 000, 35 000, and 36 000) showed no or very little alterations in the Env− mutants. In SA1926 (env-52) one protein spot at MW 48 000, proven to be an outer membrane protein, was missing, whereas a new spot appeared nearby, and other proteins in this area of the gel were reduced. An Env+ transductant selected from this strain had the wild-type protein pattern restored. The two other Env− mutants had similar but not identical changes in protein composition.
Corrosion of mild and stainless steel by four tropical Desulfovibrio desulfuricans strains
Authors: Bell R. G. , Lim Chor Kiang
Published: May 2010

The corrosion potential of four tropical Desulfovibrio desulfuricans isolates was determined using a semicontinuous batch culture technique in a 56-day test incubated at 37 °C. The corrosion potentials for mild and stainless steel of marine or brackish water isolates (0.55 and 0.0026 mg cm−2 day−1) were observed to be approximately twice those of freshwater isolates (0.23 and 0.0014 mg cm−2 day−1). Under comparable experimental conditions of severe anaerobic corrosion, stainless steel wasfound to be over 200 times more resistant than mild steel.
Survie de virus entériques adsorbés sur microfibre de verre au cours d'un transport postal
Authors: Joret J. -C. , Block J. -C.
Published: May 2010

The survival of enteric viruses (poliovirus type 1, Mahoney strain, and indigenous viruses of waste waters) has been studied after adsorption of the viruses (pH 3.5) on glass microfiber filters.After postal transport, the presence of the viruses was checked on the filters being soaked in a 3% beef extract solution (pH 7.5) either frozen or without protection against heat. Viruses were recovered at a rate of 59 to 65%.For qualitative studies, postal shipment of samples adsorbed on fiberglass may allow extension of a control system for enteroviruses in water. [Journal translation]
Adsorption of actinophage Pal 6 to developing mycelium of Streptomyces albus
Authors: Rosner Arie , Gutstein Rachel
Published: May 2010

The adsorption of actinophage Pal 6 to mycelium of different ages was studied. The rate of phage adsorption to germinating spores increased with age, being maximal at about 4 h after start of germination. The number of plaque forming units (PFU) attached to mycelium had apparently decreased later, while the phage titer in the medium supernatant was also drastically reduced. These contradictory findings were explained by the increase in the adsorption capacity of the mature mycelium due to the formation of clumps, made of network structure which adsorbed many phages, but were counted as only 1 PFU each. The growth curve of the phage in fully developed mycelium and in germinating spores were compared.
A toxigenic profile of Aeromonas hydrophila and Aeromonas sobria isolated from fish
Authors: Olivier G. , Lallier R. , Larivière S.
Published: May 2010

Forty strains of motile Aeromonas were isolated from healthy and diseased fish. These strains were identified as A. hydrophila or A. sobria. It was found that only strains of A. hydrophila produced a dermonecrotic factor and two zones of hemolysis on blood agar. All the strains of A. sorbria tested and 72% of the A. hydrophila were enterotoxigenic. Finally, we observed that only A. hydrophila strains could regularly produce hemolysin at 10 °C.
Plasmid specification of resistance to antibacterial compounds in environmental Citrobacter freundii
Authors: Austen R. A. , Trust T. J.
Published: May 2010

Citrobacter freundii from an environmental source displayed resistance to a wide variety of antibacterials. Some of these resistances could be transferred by conjugation with frequencies as high as 10−2. The complexity of plasmid involvement in the antibacterial resistance of this species was demonstrated by isolation of plasmid DNA from two isolates. In one strain, resistance to β-lactam antibiotics was specified by a 55 × 106 molecular weight plasmid, whereas kanamycin and neomycin resistance was specified by a 7 × 106 molecular weight plasmid. Resistance to chloramphenicol and tetracycline was not plasmid mediated. The other strain contained plasmids of molecular weight 113 × 106 and 80 × 106, which specified resistance to chloramphenicol, neomycin, kanamycin, tetracycline, and mercury.
Isolation of protoplasts from Aspergillus nidulans conidiospores
Authors: Bos C. J. , Slakhorst S. M.
Published: May 2010

Protoplasts were prepared from conidiospores of Aspergillus nidulans. The mononucleated conidia gave protoplasts of a uniform size, approximately 5-μm diameter, depending on the strain and the stabilizing medium used. Conidia were preincubated with 2-deoxy-D-glucose in a minimal medium at 37 °C for 3 h. The swollen conidia were collected, resuspended in a buffer containing 0.4 M (NH4)2SO4 as stabilizer, and incubated with Oerskovia lytic enzymes at 30 °C for 3 or 4 h. Approximately 80% of the conidia were converted into protoplasts. The protoplasts were separated from cell wall fragments and intact conidia by centrifugation over 30% sucrose. This isolation procedure gives a suspension of mononucleated or binucleated protoplasts suitable for recombination experiments and other studies for which a homogenous protoplast suspension is required. The procedure was also successful for Aspergillus niger.
Microbial degradation of aromatics and saturates in Prudhoe Bay crude oil as determined by glass capillary gas chromatography
Authors: Fedorak P. M. , Westlake D. W. S.
Published: May 2010

Water samples obtained from three different marine environments (including a commercial harbor, a pristine area, and an oil tanker dock area) from the coast of Washington State were challenged with Prudhoe Bay crude oil under shake-flask conditions at 8 °C. Replicate cultures were grown with and without nitrogen (NO3−, NH4+) and phosphate supplementation. After varying incubation periods, the residual oil was extracted and separated on silica gel columns into saturate and aromatic fractions and these were analyzed by glass capillary gas chromatography to detect the degradation of various compounds. After 27 days of incubation, both the aromatic and saturate fractions were extensively degraded by the microorganisms from these environments when supplemented with nitrogen and phosphorus. Without nutrient supplementation, the aromatics were more readily attacked than the saturates by the populations from the pristine environment and from the commercial harbor area. Under these limited nutrient conditions, samples from near oil tanker docks showed moderate degradation of both the saturate and aromatic fractions. Time course studies, using nutrient-supplemented marine samples, showed that the simple aromatics (e.g., naphthalene and 2-methylnaphthalene) were more readily degraded than the n-alkanes. However, once the breakdown of these saturates commenced, these were quickly removed from the oil. The aromatic degradation continued to progress from lower molecular weight, less complex molecules to larger, more complex molecules in the approximate series C2 naphthalenes; phenanthrene and dibenzothiophene; C3 naphthalenes and methylphenathrenes; C2 phenanthrenes.
A rapid one-step method for the isolation of bacteroids from root nodules of soybean plants, utilizing self-generating Percoll gradients
Authors: Reibach Paul H. , Mask Paul L. , Streeter John G.
Published: May 2010

Bacteroids were isolated from the nodules of soybean plants by means of self-generating Percoll density gradients. The entire procedure can be performed in less than 1 h using an ordinary refrigerated centrifuge and angle head rotor. All of the markers for cytosol and bacteroid fractions behaved in accord with other reports in the literature. Asparaginase, β-hydroxybutyrate dehydrogenase, and alanine dehydrogenase were all localized in the bacteroid fraction. Invertase, phosphoenolpyruvate carboxylase, and leghaemoglobin were all found in the cytosol fraction. Very little (< 7%) cross contamination between the fractions was observed. The isolated bacteroids were viable, and based on electron micrographs, were free from contaminating plant material. Since the entire procedure is performed isosmotically, very little damage to the bacteroids is likely to occur. No organic compounds, except Percoll, were added to the isolating media, thus aiding in the analysis of bacteroid and cytosol metabolites.
Cellulolytic activity of the rumen bacterium Bacteroides succinogenes
Authors: Groleau D. , Forsberg C. W.
Published: May 2010

Bacteroides succinogenes S-85 grows readily in media containing 0.2% (w/v) filter paper cellulose or microcrystalline ellulose as the carbohydrate source. During growth, the cells appear to adhere to the cellulose. Cell-free culture supermates and ell extracts from cellulose-grown cultures had very low hydrolytic activity against either filter paper or crystalline cellulose Avicel) as substrate, although H3PO4-swollen cellulose, carboxymethylcellulose, and cellobiose were readily hydrolyzed. Cells rown on either cellobiose or glucose exhibited cell-bound carboxymethylcellulase (CMCase) and cellobiase activities. Cultures rown on cellulose had seven to eight times more CMCase activity than either cellobiose- or glucose-grown cultures. Seventy ercent of the CMCase activity was present in the supernate, of which 50–60% was associated with sedimentable membranous ragments. The cellobiase, which was largely cell associated, appeared to be constitutive, and the only product detected on nzymic hydrolysis of cellobiose was glucose. The cellobiase activity was strongly inhibited by 0.02 M tris(hydroxymethyl)-minomethane (Tris), pH 7.1, but this was partially relieved by phosphate ions. These data indicate that B. succinogenes -85 contains high endo-β-1,4-glucanase and β-1,4-glucosidase-like activities.
Simple assay and extraction of periplasmic penicillinase in Escherichia coli
Authors: Choma Christin T. , Yamazaki Hiroshi
Published: May 2010

Benzylpenicillin was clearly separated from benzylpenicilloic acid by ascending chromatography on a diethylaminoethyl cellulose paper using 0.1 M ammonium acetate as a solvent. Using this chromatographic system, penicillinase was assayed by measuring the formation of [14C]benzylpenicilloic acid from [14C]benzylpenicillin. This assay remedies the lack of specificity of the commonly used iodometric assays. Periplasmic penicillinase was released from Escherichia coli by suspension in a mixture of 1% phenethyl alcohol and 5 mM ethylenediaminetetraacetate (pH 7.0). This simple extraction method not only facilitates the assay of penicillinase in an E. coli culture, but will also be useful for large-scale purification of periplasmic penicillinase.
Production of protoplasts in different yeasts by Mutanase
Authors: Stephen E. R. , Nasim A.
Published: May 2010

Mutanase (Mutanase Novo) affects the high frequency production of protoplasts in the following strains of yeas Saccharomyces cerevisiae, Schizosaccharomyces pombe, Kluyveromyces lactis, Trichosporon pullulans, and Schwanniomyce alluvius. Regeneration frequencies varied with the strain used and ranged between 10 and 18%. This enzyme preparation appear to be a very useful means of obtaining protoplasts from a wide variety of yeasts currently being used for experimental purposes
Ampicillin resistance in Neisseria denitrificans: studies on ampicillin-sensitive enzymes
Authors: MacKenzie C. R. , McDonald I. J. , Johnson K. G.
Published: May 2010

The β-lactam sensitivities of enzymes involved in peptidoglycan synthesis were examined in two strains of Neisseria 'enitrificans having widely disparate degrees of ampicillin sensitivity. One strain of N. denitrificans was 400 times more resistant) ampicillin than the other; the former is known to have altered pencillin-binding proteins. No differences in the levels of ensitivities of total peptidoglycan synthesis as measured by the incorporation of glutamate into peptidoglycan, or of D-alanine arboxypeptidase, were observed between the two strains. However, the rate of glutamate incorporation into peptidoglycan by garithmic growth phase cells was somewhat less for the ampicillin-resistant cells than for the parent cells.
Isolation and characterization of a new extracellular polysaccharide from a cellulose-negative strain of Acetobacter xylinum
Authors: Valla Svein , Kjosbakken Johs.
Published: May 2010

An extracellular, acidic polysaccharide has been isolated from the culture medium of a spontaneous cellulose-negative strain of Acetobacter xylinum. Chemical analysis shows that the polymer is composed of glucose, mannose, rhamnose, and glucuronic acid in a molar ratio approximating 3:1:1:1. No evidence for the presence of cellobiose units as structural parts in the polysaccharide has been found.
Studies on the association of the α and β2 subunits of the tryptophan synthase of Bacillus subtilis
Authors: Hoch Sallie O. , Soldau Katrin
Published: May 2010

Studies using Sephadex gel filtration indicated that the α and β2 components of the Bacillus subtilis tryptophan synthase associate to form complexes under the appropriate conditions of buffer, pH, and temperature. Monovalent cations, glycerol, and the cofactor, pyridoxal-5′-phosphate, were required to maintain an active β2 component, and in turn, affected the association of the α and β2 components. Under conditions that stabilized the individual components during their purification, the affinity of the subunits for each other was weak. Under the same buffer conditions, but at the higher pH of 7.8 at which the enzymatic activities are assayed, the individual components readily associated. The substrate serine appeared to affect complex formation but there was no effect from the indole moiety. When the temperature was raised from 4 to 22–25 °C, complex formation was observed at both pH 6.6 and 7.8. The results of these experiments are consistent with the formation of αβ2 and α2β2 species as the associated tryptophan synthase complexes of B. subtilis.
Repair of salt tolerance and recovery of lost D-alanine and magnesium following sublethal heating of Staphylococcus aureus are independent events
Authors: Hurst A. , Hughes A.
Published: May 2010

Sublethal heating of Staphylococcus aureus S6 in potassium phosphate buffer caused loss of salt tolerance, D-alanine, and magnesium. During incubation in rich complex media all three of the damaged sites were repaired. Repair occurred more slowly but went to completion in a dilute synthetic medium (DSM), free of D-ala. DSM plus penicillin or D-cycloserine allowed repair of salt tolerance but recovery of normal levels of D-ala or Mg was prevented. When DSM-repaired cells were cultured into fresh rich medium they grew rapidly after a short lag. Cells which had acquired their salt tolerance in DSM plus cycloserine and were D-ala and Mg deficient grew slowly and had a lag of 3 h. We suggest that heat damage has two separate primary targets in S. aureus cells: the membrane, which is manifested by loss of salt tolerance, and a second site, possibly teichoic acids, manifested by loss of D-ala and Mg.
Nutritional and environmental factors affecting growth and sporulation of Sporidesmium sclerotivorum
Authors: Barnett E. A. , Ayers W. A.
Published: May 2010

Three of five isolates of Sporidesmium sclerotivorum, a mycoparasite of Sclerotinia spp., grew well on an agar medium containing mineral salts, glucose, thiamine, and glutamine or Casamino acids as the nitrogen source. The nitrogen requirement for two of the isolates was satisfied by NH4Cl, Casamino acids, or glutamine. Glutamine was the best single nitrogen source. Only one isolate, CS-1, was used in further nutritional studies. The optimum concentration of glutamine for growth was 5 g/L. Glucose, mannose, mannitol, and cellobiose were excellent carbon sources. A glucose concentration of 20 g/L was optimum. Mannitol supported greater growth than glucose with Casamino acids as the nitrogen source but glucose was the superior carbon source with glutamine as the nitrogen source. Greatest growth was achieved with a combination of these carbon and nitrogen sources. Sporidesmium sclerotivorum, isolate CS-1, required thiamine for growth and sporulation. Biotin stimulated growth. The fungus developed maximally within the range of pH 5.0–5.5 and growth was greatly reduced at a pH below 4.0 or above 6.0. Control of acidity by the periodic addition of NaOH solution permitted substantially increased growth. The optimum temperature for growth was 22.5–25.0 °C but production of macroconidia was greatest at 15–20 °C.
Effect of nitrate on reduction of ferric iron by a bacterium isolated from crude oil
Authors: Obuekwe Christian O. , Westlake Donald W. S. , Cook Fred D.
Published: May 2010

A Pseudomonas sp. isolated from crude oil reduced ferric ions (Fe(III)) to ferrous ions (Fe(II)). In the presence of nitrate (NO3−) after prolonged incubation, the amount of Fe(II) was lower than in its absence. However, during short incubation periods, the presence of NO3− significantly increased (99.5% confidence limit) the amount of Fe(II) produced. The decrease in Fe(II) on prolonged incubation was associated with increased production and accumulation of nitrite (NO2−). Under low NO3− levels, where the production of NO2− was limited, a decrease in NO2− concentration was accompanied by an increase in Fe(II) production to levels comparable with those obtained in the absence of NO3−. Preinduction of cells for nitrate reductase, which favoured rapid NO2− production, resulted in a more rapid decrease in Fe(II) production than in cells that were not preinduced. It is proposed that the inhibitory effect of NO3− on microbial reduction of Fe(III) is due to a secondary reaction, which involves the chemical oxidation of Fe(II) by NO2−.
Constriction and septation during cell division in caulobacters
Authors: Poindexter J. S. , Hagenzieker J. G.
Published: May 2010

Morphogenesis of the division site in caulobacters had been described as constrictive in Caulobacter spp. and septate in Asticcacaulis excentricus. However, subsequent studies of other gram-negative genera had implied that constrictive division was an artefact resulting from inadequate preservation of septa; exploration of alternatives to osmium fixation, particularly with aldehydes, was recommended. In this study, the appearance of sectioned division sites was reinvestigated in caulobacter cells prepared by 20 different procedures varying with respect to fixation agents, media, schedules, and temperatures, to dehydrating agents, and to embedding resins. Three types of division site morphogenesis were observed: constriction in C. bacteroides and C. crescentus, partial septation in C. leidyi, and complete, undivided septation in A. excentricus and A. biprosthecum. The anatomy of the division site depended on the bacterial strain, not on the method of preparation of the cells for sectioning. These studies confirm the earlier observations on osmium-fixed caulobacter cells and lead to the general conclusion that gram-negative bacteria with tapered poles probably divide by constriction, whereas septation results in blunt cell poles. A pattern of spiral, rather than circular, insertion of new envelope subunits at the cell equator is proposed as a basic developmental difference between constrictive and septate fission in gram-negative bacteria. Since caulobacter prosthecae can develop as extensions of tapered poles formed by constriction, whereas subpolar or lateral prosthecae occur in species with blunt poles resulting from septation, the site of formation of a thick septum appears unsuitable as a site of subsequent envelope outgrowth.
Isolation and characterization of the plasma membrane and the outer membrane of Deinococcus radiodurans strain Sark
Authors: Thompson B. G. , Murray R. G. E.
Published: May 2010

Deinococcus radiodurans strain Sark, although gram-positive, has a complex cell wall profile that includes an outer membrane-like structure. The outer cell envelope layers formed blebs throughout the growth cycle, which were shed as large vesicles (0.5–3.5 μm in diameter) from approximately 5% of the cell population. Instability of the compartmentalized layer immediately beneath the outer membrane was the cause of the vesicle production. This instability was accentuated by treatment with 10% NaCl, which released the outer membrane from all cells without disrupting the peptidoglycan layer, and provided an outer membrane fraction uncontaminated by plasma membrane. Cells so treated formed protoplasts after sequential treatment with 6 M urea, trypsin, and the supernatant from batch cultures of Lysobacter enzymogenes 495. The plasma membrane was isolated from lysed protoplasts. The absence or presence of catalase activity, and differences in lipid composition, were used to differentiate between plasma membrane and outer membrane.
Methionine transport by mycelia of Fusarium oxysporum f. sp. lycopersici
Authors: Barran Leslie R.
Published: May 2010

Mycelia of Fusarium oxysporum f. sp. lycopersici accumulated L-methionine by an energy-dependent process, and the energy required for uptake may be derived from either respiration or glycolysis. The pH optimum for transport was 4 and the temperature optimum was 35 °C. The apparent Km for methionine uptake was 2.5–3.3 μM and the Vmax was 0.24–0.30 nmol∙min−1∙mg dry weight−1. S-adenosylhomocysteine (Ado-Hcys) was the major metabolic product of methionine although S-adenosylmethionine (Ado-Met), homocysteine (Hcys), and an unidentified metabolite (compound X) were also detected. The failure to demonstrate efflux of accumulated methionine in the presence of the uncoupler 2,4-dinitrophenol or excess unlabeled methionine was probably due to the fact that methionine was rapidly metabolized within the cells.Acidic and basic amino acids, and those amino acids having less than a four-carbon chain, did not inhibit methionine uptake. The rate of uptake of methionine, which was greatest in log phase mycelia, decreased substantially as the cells entered the stationary phase.
The cell walls of Agaricus bisporus and Agaricus campestris fruiting body hyphae
Authors: Novaes-Ledieu M. , Mendoza C. Garcia
Published: May 2010

The hyphal walls of Agaricus bisporus and Agaricus campestris fruiting bodies were isolated and purified. Quantitative analyses revealed that these walls consisted mainly of carbohydrates (78.3–79.2%), lipids (9.9–10.1%), and proteins (8.7–10.2%). The major components of carbohydrate polymers were glucose, N-acetylglucosamine, and glucosamine. In addition, small quantities of galactose and mannose have been found.N-Acetylglucosamine and glucosamine were identified chemically and enzymatically, and also by infrared spectrum and X-ray diffraction analyses, as chitin and chitosan. Neutral polysaccharides include an alkali-soluble glucan with α(1–3) linkages and a β(1–3)- and β(1–6)-linked glucan.The lipid fractions in both hyphal walls contained precursors of melanin, this pigment being largely represented in Agaricus spore walls. Amino acids analyses indicate that structural wall proteins were very similar in both organisms.In electron micrographs of ultrathin sections of hyphae no distinct layering was apparent in contrast with spore walls of the same organism, which show two wide well-defined layers.
Factors affecting vesicle formation and acetylene reduction (nitrogenase activity) in Frankia sp. CpI1
Authors: Tjepkema John D. , Ormerod William , Torrey John G.
Published: May 2010

Vesicle formation and acetylene reduction (nitrogenase activity) were observed when washed hyphae from cultures of Frankia sp. CpI1 were transferred to a nitrogen-free medium containing ethylenediaminetetraacetic acid and succinate. Succinate could be replaced by malate or fumarate, but not other carbon sources. Maximum acetylene reduction and vesicle numbers were observed at a pH of 6.0–6.5, at 25–30 °C, and at atmospheric [Formula: see text] or somewhat less (5–20 kPa). Addition of 1 mM NH4Cl almost completely inhibited vesicle formation and acetylene-reducing activity, but did not immediately inhibit such reducing activity by cultures with preexisting vesicles. Acetylene-reducing activity was never observed in the absence of vesicle formation.
Plasmid DNA in acidophilic, chemolithotrophic thiobacilli
Authors: Martin Phyllis A. W. , Dugan Patrick R. , Tuovinen Olli H.
Published: May 2010

Plasmid patterns were determined in 15 strains of iron-oxidizing Thiobacillus ferrooxidans. In four of these strains plasmid DNA was not detected. In the other strains the molecular weights of plasmids ranged from 5 × 106 to 50 × 106 and each strain had a different plasmid composition. The change of growth substrate from ferrous iron to tetrathionate did not affect the plasmid pattern in T. ferrooxidans nor did it in T. acidophilus, which was adapted from glucose to grow on tetrathionate.