bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation among different cultures of Bradyrhizobium japonicum strains USDA 110 and 122
Authors: Mullen Michael D. , Wollum II A. G.
Published: November 2009

Cultures of Bradyrhizobium japonicum strains USDA 110 and USDA 122 were obtained from six different laboratories (designated BV, IA, LA, MIN, NC, or PR) and examined for variability in colony morphology, growth in broth, antibiotic resistance, symbiotic efficiency, and nodulation competition against a common strain. Cultures within both strains exhibited variability in colony morphology and intrinsic antibiotic resistance. When grown in broth culture, IA 110 and PR 110 yielded somewhat lower cell numbers and much lower optical densities after 8 days than the other USDA 110 cultures, indicating reduced extracellular polysaccharide production. No differences in cell numbers for USDA 122 cultures were observed, but optical density values were much lower for IA 122 and MIN 122 than for the other USDA 122 cultures. Few differences in symbiotic efficiencies were observed. IA 122 was superior to the other USDA 122 cultures after 28 days, but after 50 days no differences among USDA 122 cultures were observed. In nodulation competition studies against USDA 31, MIN 110 was most competitive at low numbers of USDA 31 while BV 110 became more competitive relative to the other cultures as USDA 31 numbers increased. PR 110 was the least competitive USDA 110 culture against both USDA 31 and USDA 123. Among USDA 122 cultures, LA 122 and BV 122 were the most and least competitive against USDA 31, respectively. The results indicate that independent culturing has resulted in the divergence of some phenotypic characteristics of these strains.Key words: nodulation competition, colony morphology, antibiotic resistance.
Biotransformation of dibenzothiophene to dibenzothiophene sulfone by Pseudomonas putida
Authors: Mormile MeLanie R. , Atlas Ronald M.
Published: November 2009

A strain of Pseudomonas putida was isolated that transforms dibenzothiophene (DBT) to DBT sulfone (DBT-5-dioxide) via DBT-5-oxide. It also degrades DBT to 3-hydroxy-2-formyl benzothiophene via an alternate and previously described pathway, and to an unidentified red crystalline compound. Neither DBT sulfone nor 3-hydroxy-2-formyl benzothiophene are further degraded by this organism.Key words: dibenzothiophene, microbial degradation, Pseudomonas, dibenzothiophene sulfone, sulfur metabolism.
Relationship between aeration, carbon source, and respiration yield and the ethylene production and differentiation of static cultures of Penicillium cyclopium and P. velutinum
Authors: Pažout Jaroslav , Pažoutová Sylvie
Published: November 2009

Fully aerated surface cultures of Penicillium cyclopium and P. velutinum grown on liquid medium with 2-oxoglutarate or glutamate (34 mM) produced ethylene in association with the formation of aerial hyphae at about the 5th day (ethylene peak EP 1), its concentration then declined, and rose again during conidiation at about the 7th day (peak EP 2). In P. cyclopium glucose (22.2 mM) shortened differentiation, EP 1 and EP 2 merged, and culture pH dropped to 1.8. Methionine (34 mM) prevented the formation of aerial mycelium in P. cyclopium and penicilli initiation in P. velutinum; ethylene production was low. Under conditions of delayed aeration, P. cyclopium grown on glucose produced no ethylene and weak formation of immature conidia was observed. On other substrates both conidiation and ethylene production occurred after reaeration, but phase EP 1 was lacking. Penicillium velutinum grown on 2-oxoglutarate and glutamate with delayed aeration developed immature conidia within 36 h and traces of ethylene were produced. In the cultures with methionine and glucose, conidiation and ethylene production occurred after reaeration, but phase EP 1 was missing. In both strains, no ethylene was formed under anaerobic conditions. Intensively producing cultures were characterized by a narrow range of respiration yields (6.8–7.5 g dry weight per mole of consumed O2). A prerequisite for high ethylene production was a drop in the phosphate content of the medium to less than 0.45 mM.Key words: Penicillium cyclopium, Penicillium velutinum, ethylene, conidiation.
Effects of culture conditions on yield of Shiga-like toxin-IIv from Escherichia coli
Authors: MacLeod D. L. , Gyles C. L.
Published: November 2009

The effects of selected culture conditions on production of Shiga-like toxin-II variant by an edema disease strain of Escherichia coli (412) and E. coli TB1 (pCG6) containing the cloned genes for Shiga-like toxin-II variant were examined. Incubation time, culture media, incubation temperature, starting pH of the culture medium, aeration, static culture, anaerobiosis, carbon sources, amino acids, antibiotics, and mitomycin C were investigated. The study showed that Shiga-like toxin-II variant was primarily cell associated and that strain TB1 (pCG6) produced as much as 100 times more toxin than did strain 412. Culture conditions that resulted in the greatest yield of Shiga-like toxin-II variant were incubation at 37 °C for 24 h with shaking in syncase broth initially adjusted to pH 8.5. Aerobic culture with shaking resulted in higher yields of Shiga-like toxin-II variant than did static aerobic or anaerobic culture. Addition of various carbon sources or amino acids, or tetracycline, lincomycin, or trimethoprim: sulfadoxine did not increase yields of toxin. The amount of Shiga-like toxin-II variant in supernatant preparations from strain TB1 (pCG6) was significantly increased by addition of mitomycin C to the culture medium.Key words: Shiga-like toxin-II variant, verotoxin, Escherichia coli, edema disease, culture conditions.
Accumulation of incomplete metabolic side products of lipid A in Salmonella typhimurium during inhibition of 3-deoxy-D-manno-octulosonate incorporation by a new class of antibacterial agents
Authors: Kadam Sunil K. , Doran Colette C. , Goldman Robert C.
Published: November 2009

A new class of antibacterial agents for Gram-negative bacteria, rationally designed to inhibit the incorporation of 3-deoxy-D-manno-octulosonate into lipopolysaccharide (LPS), was recently reported. In Salmonella typhimurium, where the lipid A species are well characterised, it was previously demonstrated that the addition of a compound which inhibits the enzyme 3-deoxy-manno-octulosonate cytidylytransferase (CMP-KDO synthetase; EC 2.7.7.38) leads to rapid accumulation of lipid A derivatives. The major lipid A species, IVA (O-(2-amino-2-deoxy-β-D-glucopyranosyl)-(1-6)-2-amino-2-deoxy-α-D-glucose, acylated at positions 2, 3, 2′, 3′ with β-hydroxymyristoyl groups and bearing phosphates at positions 1 and 4′), was shown to be converted mainly to LPS by pulse-chase experiments in the absence of inhibitor. Labelled precursor (IVA) was also chased to other more polar lipid A derivatives. During chase in the presence of inhibitor, there was no conversion to LPS, while the major lipid A species was converted to the same polar lipid A derivatives as in chase without inhibitor. Our data indicate that despite the accumulation of several species of lipid A derivatives during inhibition of LPS synthesis, only IVA is destined for synthesis of mature LPS when LPS synthesis resumes. The more polar lipid A derivatives would thus represent aberrant side reaction products which occur when the pathway is inhibited.Key words: CMP-KDO synthetase, lipopolysaccharide synthesis, lipid A precursor, 3-deoxy-D-manno-octulosonate analogs.
Characterization of a monoclonal antibody against active pectate lyase from Erwinia carotovora
Authors: Ward L. J. , Boer S. H. De
Published: November 2009

A monoclonal antibody (2E2) produced against pectate lyase from Erwinia carotovora ssp. carotovora reacted with a 41-and a 44-kilodalton protein on Western blots of concentrated Erwinia culture supernatants resolved by sodium dodecyl sulphate – polyaerylamide gel electrophoresis. It was unequivocally shown that monoclonal 2E2 reacted with an active form of pectate lyase by affinity purifying the antigen with the monoclonal. The affinity-purified antigen was enzymatically active and moved as a single protein band in a nonequilibrium isoelectric focusing gel. Monoclonal 2E2 reacted with the pectate lyases of a diverse range of E. carotovora ssp. carotovora, ssp. atroseptica, and ssp. betavasculorum strains, as well as with one of three strains of E. chrysanthemi. The electrophoretic mobility of the major protein (44 kilodaltons) that reacted with 2E2 was identical within a subspecies but differed among subspecies.Key words: Erwinia carotovora, pectate lyase, monoclonal antibody.
Variation and composition of bacterial populations in the rhizospheres of maize, wheat, and grass cultivars
Authors: Miller H. J. , Henken G. , Veen J. A. van
Published: November 2009

Differences in the size and composition of bacterial populations found in the rhizospheres of maize, wheat, and grass were compared. Significant differences in the fluorescent pseudomonad and "coryneform" groups were found among the cultivars of each plant species. Only between the two maize cultivars, reported to be resistant and susceptible to Fusarium species, and between the two grass lines, known to be resistant and susceptible to Dreschera poae, could significance be found in the total numbers of bacteria counted. In each case higher bacterial counts were recorded in the rhizospheres of cultivars susceptible to disease. No conclusion could be reached with regard to differences that occurred between the two cultivars of wheat that are known to differ in tolerance to pH. Although actinomycetes appeared to represent a high percentage of the total bacterial population in maize, insufficient data prevent further interpretation. Bacillus numbers do not differ with any significance betewen cultivars or even between cultivars and counts made in root-free soil. Both the Bacillus and fluorescent pseudomonad groups were found to be represented in lower numbers in the rhizosphere of all cultivars than either the actinomycetes or "coryneform" groups. The findings of this study correlate highly with previously published work in stressing the importance of the plant's influence on the bacteria in its own rhizosphere. As this may mean that a plant, given the right genetical configuration, can influence the development of a favourable rhizosphere flora, the mechanism involved in this relationship should be investigated.Key words: bacteria, disease resistance, pH, rhizosphere, selective stimulation.
Binding specificities of heat-labile enterotoxins isolated from porcine and human enterotoxigenic Escherichia coli for different gangliosides
Authors: Sugii Shunji , Tsuji Takao
Published: November 2009

The binding specificities of heat-labile enterotoxins (LTp and LTh) isolated from porcine and human enterotoxigenic Escherichia coli on human erythrocytes were studied by competitive binding assays using different gangliosides as inhibitors. The binding of 125I–labeled LTp to neuraminidase-treated human type A erythrocytes was most effectively inhibited by ganglioside GM1 Ganglioside GM1 was 11 and 105 times more potent than gangliosides GD1b and GM2, respectively. Gangliosides GD1a, GT1b, and GM3 were much less potent. Similar results were also obtained in competitive binding assays with the 125I-labeled B subunit of LTh and neuraminidase-treated human type B erythrocytes, and in those with 3H-labeled ganglioside GM1 and LTp-coupled Sepharose 4B. The binding of 3H-labeled ganglioside GM1 to LTp was not effectively inhibited by galactose-β(1 → 3)N-acetyl-D-galactosamine at the highest concentration used. These findings suggest that the combining sites of LTp and LTh may be specific for at least the galactose-N-acetyl-D-galactosamine-galactose (N-acetyl-neuraminic acid) portion of ganglioside GM1.Key words: binding specificity, heat-labile enterotoxin, enterotoxigenic Escherichia coli, ganglioside.
Composition of the rumen ciliate population in experimental herds of cattle and sheep in Lethbridge, Alberta, Western Canada
Authors: Imai S. , Han S. S. , Cheng K.-J. , Kudo H.
Published: November 2009

Rumen ciliate populations were surveyed in 11 Holstein cattle and 6 sheep in Lethbridge (Alta., Canada) to determine species distribution in this Western Canadian environment. A total of 28 ciliate species were identified in cattle and 17 in sheep. The average total number of ciliates per millilitre of rumen content was 6.9 × 104 in cattle and 1.9 × 105 in sheep. The average number of species per host was 20.5 in cattle and 13.8 in sheep. Of the ciliate species detected, species of Entodinium appeared most frequently both in cattle and in sheep. Diplodinium polygonale, Eodinium lobatum, Eo. monolobum, Eremoplastron rostratum, Ostracodinium clipeolum, Os. mammosum, and Ophryoscolex purkynjei were not detected in sheep. In contrast, Ophryoscolex caudatus was not found in cattle. These data indicate that the ciliate faunas of cattle and sheep in this Western Canadian environment are similar to those found in Japan.Key words: ciliate population, rumen, cattle, sheep.
Colony counts and characterization of bacteria adherent to the rumen wall and desquamated epithelial cells in conventional young lambs
Authors: Rieu Françoise , Fonty Gérard , Gouet Philippe
Published: November 2009

Characterization and enumeration of the adherent epimural community of the rumen wall of young, conventionally reared lambs were carried out from 2 to 21 days after birth. Three hundred strains were isolated by anaerobic procedures from three sites: dorsal, ventral, and caudal sacs, and from the sloughed epithelial cells. The population of epimural bacteria was very dense from the first days of the lamb's life. This population increased slightly with age. During the first week the counts were similar in the dorsal and ventral sacs, but they were 10 to 100 times lower in the caudal sac. Total counts for anaerobic bacteria were higher than the counts for aerobic bacteria. The isolated strains were distributed into 19 groups: 11 groups included aerotolerant strains, and 8 others, strictly anaerobic strains. During the first week the facultative microflora was mainly composed of Escherichia coli and Streptococci. Later, the epimural community was more complex and included Staphyloccus, Micrococcus, and Gaffkya. The strictly anaerobic microflora was mainly composed of Clostridium, Peptostreptococcus, Veillonella, Propionibacterium, and Acidaminococcus. Some of these strains appeared to be similar to those previously isolated from the rumen fluid of young lambs; however, the genera Micrococcus, Veillonella, Gaffkya, and Acidaminococcus, and E. coli seemed to be specific of the rumen wall tissues.Key words: rumen, lamb, microflora, rumen wall.
Implications of natural ethylene cycling processes for forest soil acetylene reduction assays
Authors: Hendrickson O. Q.
Published: November 2009

Under aerobic conditions, ethylene production and oxidation occurred simultaneously in organic and mineral horizons of a northern hardwood forest. Ethylene oxidation rates in mineral soil were high (up to 25 nmol∙g−1∙day−1) relative to other forest soils, and exceeded production rates unless moisture contents were raised above saturation. Acetylene inhibits ethylene oxidation while allowing ethylene production to proceed; control samples for acetylene reduction assays should therefore contain acetylene plus a nitrogenase inhibitor such as carbon monoxide if forest soil nitrogenase activity is to be accurately quantified. A level of 7 kPa carbon monoxide gave complete nitrogenase inhibition in active forest floor samples in the presence of acetylene; carbon monoxide was applied 2 h in advance of acetylene to compensate for its lower solubility in water. Use of this methodology revealed a strong inhibitory effect of saturated water contents on forest floor acetylene reduction activity, suggesting that aerobic N2-fixing activity predominated in unamended forest soil samples.Key words: nitrogenase, acetylene reduction, ethylene formation, forest soil.
Purification and partial characterization of a cytotonic enterotoxin produced by Aeromonas hydrophila
Authors: Chopra A. K. , Houston C. W.
Published: November 2009

This report describes the purification and partial characterization of a cytotonic enterotoxin produced by a human diarrheal isolate (SSU) of Aeromonas hydrophila. The extracellular enterotoxin was purified by (NH4)2SO4 precipitation, hydrophobic column chromatography, and chromatofocusing. The highly purified enterotoxin exhibited a molecular mass of 44 kDa and an isoelectric point in the range of 4.3–5.5 as determined by chromatofocusing. Western blot analysis using Aeromonas anti-enterotoxin revealed a single band at 44 kDa; however, cholera antitoxin failed to detect the enterotoxin antigen. This non-cholera toxin cross-reactive (non-CTC) enterotoxin was biologically active in vivo as determined by rabbit ligated ileal loop and rabbit skin vascular permeability assays. Biological activity also was expressed in vitro by this toxin as measured by the elongation of Chinese hamster ovary (CHO) cells. The enterotoxic activity associated with this molecule was neutralized completely by homologous antibodies but not by cholera antitoxin. The purified toxin preparation was free of hemolytic and cytotoxic activities as determined by its inability to lyse rabbit red blood cells or damage CHO cells, respectively. Furthermore, this toxin induced the elevation of cAMP in CHO cells suggesting thereby that the mechanism of action of Aeromonas non-CTC enterotoxin may be similar to heat-labile enterotoxins of Escherichia coli and Vibrio cholerae.Key words: Aeromonas hydrophila, cytotonic enterotoxin, cholera toxin, cAMP
Identification of a black yeast isolated from oak bark as belonging to the genus Phaeococcomyces sp. Analysis of melanin produced by the yeast
Authors: Butler M. J. , Lazarovits G. , Higgins V. J. , Lachance M.-A.
Published: November 2009

A black fungus isolated from oak bark was identified as a member of the yeast-like genus Phaeococcomyces. While no sexual reproduction was observed, the isolate showed characteristics associated with basidiomycetous yeasts: it was non-fermentative, produced extracellular urease, was positive with the diazonium blue B colony colour test, and had an enteroblastic form of budding. The isolate produced a black pigment constitutively which was shown to be a melanin. Production of the pigment was inhibited by the incorporation of low levels of the fungicide tricyclazole in growth media, inidicating that it was a pentaketide melanin. Pigmentation mutants were produced. Albino mutants did not produce melanin. Diffusion mutants accumulated the pentaketide melanin pathway oxidation products flaviolin and 2-hydroxyjuglone in culture media. Cross-feeder mutants accumulated scytalone, a pentaketide melanin pathway intermediate, in culture media, and caused albino mutants to melanize when grown in proximity to them on agar plates. A single mutant was isolated which excreted 1,8-dihydroxy naphthalene, the end product of the pathway. Broth cultures of Phaeococcomyces sp. in stationary growth phase released melanin in the form of granules, with an average diameter of 30 nm.Key words: black yeast, melanin production, Phaeococcomyces sp.
The influence of lipopolysaccharide on the transformation efficiency of Klebsiella pneumoniae
Authors: Camprubí Silvia , Regué Miquel , Tomás Juán
Published: November 2009

The presence of O antigen of the lipopolysaccharide on Klebsiella pneumoniae is responsible for the low transformation frequencies observed. No significant influence of capsular polysaccharide could be observed. This phenomenon was independent of the transformation procedure and plasmid size.Key words: lipopolysaccharide, capsular polysaccharide, transformation, Klebsiella pneumoniae.
Étude préliminaire des communautés bactériennes épiphytes de Laminara digitata
Authors: Corre Sophie , Prieur Daniel , Chamroux Simone , Floch Jean-Yves , Hourmant Annick
Published: November 2009

Algal samples from different parts of the frond of Laminaria digitata (young, adult and aged tissues) and from macroscopic fragments naturally separated from the thallus were collected on the Atlantic coast of France (Brittany) during winter and spring. Bacterial communities associated with the different levels were compared, and the ATP content was determined and used as an indicator of the physiological state of the tissues. It is higher in young tissue (55 nmol/g of fresh kelp) than in fragments (9 nmol/g of fresh kelp), showing a decrease in the number of metabolically active cells. If total bacterial density values are relatively close on the different parts of the kelp (average, 2.9 × 107 bacteria/cm2), culturable microflora increased from young tissue (minimum, 15 cfu/cm2) to fragments (average, 3.6 × 107 bacteria/cm2). Characterization of strains showed an increase of metabolic activity together with a diversification in the culturable fraction with the age of algal tissues.Key words: epiphytic bacteria, kelp, Laminaria digitata.
The sorption of metals to Bacillus subtilis walls from dilute solutions and simulated Hamilton Harbour (Lake Ontario) water
Authors: Mayers I. Trent , Beveridge Terry J.
Published: November 2009

Purified cell walls of Bacillus subtilis were reacted with various metals in dilute solutions and a simulated Hamilton Harbour (Lake Ontario) water. Atomic absorption spectrophotometry revealed that iron was sorbed to the walls preferentially and caused the walls to adhere together to form macroscopic floes, which were easily sedimented by gravity. Electron microscopy and energy dispersive X-ray analysis of the floes showed that the bacterial walls were embedded in an iron matrix presumed to be iron oxyhydroxide. The sorption of iron to the walls was also found to enhance the uptake of other metals such as chromium and aluminum. This sorption suggests that bacteria may play a role in the initial formation of metal rich sediments. It may also have important implications for the general transport of metals to the sediments from the water column in fresh water environments like Hamilton Harbour by all types of particulate biological debris.Key words: metal sorption to bacterial walls.
Nonspecific inhibition of proline dehydrogenase synthesis in Escherichia coli during osmotic stress
Authors: Deutch Charles E. , Hasler James M. , Houston Rochelle M. , Sharma Manish , Stone Valerie J.
Published: November 2009

L-Proline, which is accumulated by Escherichia coli during growth in media of high osmolality, also induces the synthesis of the enzyme degrading it to glutamate. To determine if proline catabolism is inhibited during osmotic stress, proline utilization and the formation of proline dehydrogenase were examined in varying concentrations of NaCl and sucrose. Although the specific growth rate of E. coli with proline as the sole nitrogen source diminished as the solute osmolality increased, a comparable reduction in growth rate occurred with ammonium as the primary nitrogen source. Proline catabolism, as measured in whole cells by the conversion of [14C]proline to [14C]glutamate, was only slightly inhibited by solute osmolalities up to 1.0 osmol/kg; more than 50% of the initial activity was still found at 2.0 osmol/kg. By contrast, the specific activity of proline dehydrogenase in bacteria grown in the presence of added solutes decreased to less than 20% of the control level. This reduction was related to a lower rate of synthesis, but was independent of genes currently known to be involved in osmoregulation or proline metabolism. The specific activities of tryptophanase, β-galactosidase, and histidinol dehydrogenase were also reduced under similar growth conditions. These results indicate that while proline catabolism is not directly inhibited by high solute concentrations, prolonged exposure to osmotic stress leads to its reduction as part of a more general metabolic response.Key words: osmotic stress, proline, proline catabolism, proline dehydrogenase, PutA protein.
Analyses of fermentation products of Listeria species by frequency-pulsed electron-capture gas–liquid chromatography
Authors: Daneshvar Maryam I. , Brooks John B. , Malcolm Georgia B. , Pine Leo
Published: November 2009

Aerobic fermentation broths of eight Listeria monocytogenes strains, two or more strains of the remaining six Listeria species, and one strain of Jonesia denitrificans were examined by frequency-pulsed electron-capture gas–liquid chromatography for carboxylic acids, alcohols, amines, and hydroxy acids. All species produced acetic, isobutyric, butyric, isovaleric, phenylacetic, lactic, 2-hydroxybutyric, 2-hydroxyvaleric, and 2-hydroxyisocaproic acids. Propionic acid was not formed, and traces of isocaproic acid were observed. Of the alcohol and amine derivatives observed, only acetylmethylcarbinol, butylamine, and putrecine were identified. Recognition of the products of glucose and amino acid metabolism serves to further characterize the members of the genus Listeria both taxonomically and physiologically.Key words: Listeria, growth products, frequency-pulsed electron-capture gas–liquid chromatography.
Spore germination and the life cycle of Frankia in vitro
Authors: Tzean S. S. , Torrey John G.
Published: November 2009

Bacterial spores of Frankia produced in defined culture media were collected by filtration after washing in amounts approximating 106 spores/mL. Frankia strains UFGCeI5 from Casuarina equisetifolia and UFGCgI1 from C. glauca showed spontaneous release of spores in culture; strains HFPCcI3 from C. cunninghamiana and HFPAllI1 from Allocasuarina lehmanniana showed low spore release in culture unless homogenized. Spore germination was tested on plates of agar nutrient media under different physical and chemical environments. Strain CeI5 showed about 15% germination within 2 days in a defined (BAP) medium with an optimum pH of 6.0–6.8 at 28–35 °C. Under these conditions, strain CcI3 germinated less than 0.5%. In a series of trials with increasingly complex media, strain CeI5 showed 75% spore germination in 3 days at 28 °C and pH 6.7 in the most complex medium tested. Additions of specific single organic compounds to BAP medium caused either strong inhibition or slight stimulation of spore germination. Frankia strains that showed spontaneous spore release germinated better than strains that did not release. Spore germination in Frankia strains is markedly influenced by their strain origin and by the physical and chemical environment in which they are placed.Key words: Casuarina, Frankia, life cycle, spore germination.
Indirect evidence for cellulase production by Rhizobium in pea root nodules during bacteroid differentiation: cytochemical aspects of cellulose breakdown in rhizobial droplets
Authors: Chalifour François-P. , Benhamou Nicole
Published: November 2009

Cytochemical localization of cellulosic β-(1–4) glucans in pea (Pisum sativum L.) nodules at different stages of infection by an effective isolate of Rhizobium leguminosarum biovar viceae was studied using a gold-complexed exoglucanase. Cellulose subunits were present in great amounts in root cell walls, as shown by intense and regular labeling by gold particles. Labeling was unevenly distributed over the thin walls of emerging infection threads. In more developed infection threads, labeling was more intense and evenly distributed than in emerging threads, although slightly altered, unlabeled wall areas were frequently observed at the growing tips. Droplets containing rhizobia, which originated from infection threads, were surrounded by labeled wall-like material. Rhizobial droplets were either single- or multi-celled, and were sometimes separated by inner, unevenly labeled compartments. The surrounding wall-like material was irregularly labeled, and unlabeled wall areas, neighbouring intensely labeled ones, were observed frequently. There was an absence of labeling ahead of the rhizobia that escaped from the droplets, but degenerating wall-like material was present around the escaping rhizobia, mainly on their sides. At more advanced stages of development, labeling was present only over the outermost wall layers of rhizobial droplets, indicating that inner portions were degraded first. These observations suggest that a hydrolytic enzyme is involved in the sequence of events from infection thread formation through rhizobial release in the host cell cytoplasm, and that the hydrolytic enzyme is of rhizobial origin.Key words: Rhizobium–Pisum symbiosis, root nodules, rhizobial droplets, cellulose, colloidal gold.
Control and localization of the phosphatases in conidia of Neurospora crassa
Authors: Nahas E.
Published: November 2009

Repressible acid, repressible alkaline, and constitutive alkaline phosphatases were studied with respect to their control and localization in conidia of Neurospora crassa. In contrast to constitutive alkaline phosphatase, the production and secretion of repressible phosphatases is regulated by phosphate level and pH of the culture medium. Phosphatase activity increased with conidial germination and was detectable partially in the growth medium after 5 h incubation. These enzymes were found to be located in different cell compartments. Part of the whole cell enzyme activity involved a soluble exoconidial fraction, and another part, a cell-bound enzyme that remained after successive washes. The cell-bound enzyme was sensitive to treatment with dilute acid and was thought to be located in the mural space. A third part of the enzyme activity was judged to be intracellular, as shown by treatments with surface-active agents and heat, which disrupted the conidia or destroyed the conidial permeability barriers. On the basis of these criteria, the constitutive alkaline phosphatase was considered to be more cryptic than the repressible phosphatases. The alkaline phosphatases were also active during heat treatment, suggesting they may be involved in the mechanism of secretion.Key words: Neurospora crassa, repressible acid phosphatase, repressible alkaline phosphatase, constitutive alkaline phosphatase, conidia.
Purification and characterization of two xylanases from Chaetomium thermophile var. coprophile
Authors: Ganju Ramesh K. , Vithayathil Paul J. , Murthy S. K.
Published: November 2009

Two xylanases (I and II) out of several extracellular xylanases produced by the thermophilic fungus Chaetomium thermophile var. coprophile were purified to homogeneity by a combination of ion exchange and gel filtration chromatographic procedures. They had molecular weights of 26 000 (xylanase I) and 7000 (xylanase II). The temperature optima for xylanase I and II were 70 and 60 °C, and they were optimally active at pH 4.8–6.4 and 5.4–6.0, respectively. Xylanase I was found to be comparatively more stable than xylanase II at higher temperatures. Amino acid composition indicated that xylanase I contained high amounts of glycine, threonine, and low amounts of histidine and sulphur-containing amino acids. Each enzyme released different hydrolysis products from larch wood xylan. Xylanase I produced mainly xylobiose and xylotriose whereas xylanase II produced mainly xylobiose.Key words: Xylanase, enzyme purification, characterization, Chaetomium thermophile.
Molecular comparison of prolate- and isometric-headed bacteriophages of lactococci
Authors: Powell Ian B. , Arnold Phillip M. , Hillier Alan J. , Davidson Barrie E.
Published: November 2009

Twelve lytic phages that infect lactococci (eight prolate-headed and four isometric-headed phages) were compared via DNA–DNA hybridization, DNA restriction site mapping, genome size estimation, and analysis of virion proteins. Prolate-headed phages carried double-stranded DNA of 21.8 to 23.4 kilobases and showed three major virion proteins in SDS-polyacrylamide gel electrophoresis. Isometric-headed phages carried double-stranded DNA of 28.1 to 30.4 kilobases and showed one major virion protein. The DNA of all phages had cohesive ends. No DNA hybridization was observed between the two phage types. Restriction endonuclease cleavage site mapping of DNA showed similarities between some of the phages.Key words: Lactococcus lactis, bacteriophages, genome size, phage types, restriction site mapping.
Actinomycete morphology in shaken culture
Authors: Lawton Peter , Whitaker Allan , Odell David , Stowell Julian D.
Published: November 2009

The morphology of 49 Streptomyces strains and eight other actinomycetes was studied in shaken liquid culture, using a range of spore inocula in a complex medium. Results showed that each strain would produce one, two, or more different gross morphological types throughout the spore inoculum range tested. The morphological forms that were observed included compact pellets, spiky or fluffy pellets, oblong pellets, flakes, hydrophobic rafts, aggregates, dispersed mycelium, fragmented mycelium, or combinations of these forms. Two strains of S. viridochromogenes developed different ranges of morphology in the test conditions.Key words: Streptomyces, pellets, spore inoculum.
Characterization and purification of extracellular proteases of Trichomonas vaginalis
Authors: Garber Gary E. , Lemchuk-Favel Laurel T.
Published: November 2009

Extracellular protease activity was detected in serum-free culture filtrates of Trichomonas vaginalis. The activity was demonstrated by hydrolysis of hide powder azure and possessed the characteristics of cysteine type proteases: inhibition by N-ethyl maleimide, Cu2+, antipain, N-tosyl-L-phenylalanine chloromethyl ketone, N-tosyl-L-lysine chloromethyl ketone, leupeptin, chymostatin, and iodoacetamide, and enhancement by cysteine, EDTA, and dithiothreitol. The activity was optimal at acid pH and the protease was also active on peptide nitroanilides with arginine derivatives. Purification of this activity by ethanol precipitation, ammonium sulfate fractionation, ion exchange chromatography, and gel filtration resulted in the isolation of two proteases estimated by sodium dodecyl sulfate – polyacrylamide gel electrophoresis to have molecular masses of 60 and 30 kilodaltons (kDa), respectively. The larger molecular mass protease broke down during purifications to two subunits of approximately 23 and 43 kDa, as determined by gel electrophoresis. Rabbit sera derived by immunization with the 23-kDa subunit cross-reacted by immunoblot with the 60- and 43-kDa subunits, but not with the 30-kDa protease. These soluble products of T. vaginalis growth could be important pathogenically in establishing T. vaginalis infection in the normally acid (pH ≤ 4.5) environment of the vagina.Key words: Trichomonas vaginalis, trichomoniasis, vaginitis, protease, pathogenesis.
Concentration of Giardia lamblia cysts, Legionella pneumophila, Clostridium perfringens, human enteric viruses, and coliphages from large volumes of drinking water, using a single filtration
Authors: Payment Pierre , Bérubé Alain , Perreault Daniel , Armon Robert , Trudel Michel
Published: November 2009

Poliovirus, coliphages, Giardia lamblia cysts, Clostridium perfringens spores, and Legionella pneumophila were concentrated simultaneously in a single pass by sequential filtration of large volumes of drinking water through 3- and 1-μm wound electronegative fiberglass cartridge filters (25.4 cm). Filtration was performed under acidic conditions (pH 3.5) in the presence of 0.001 M aluminum chloride to enhance adsorption. Elution of all the microorganisms entrapped or adsorbed to the filters was obtained by a slow backwash elution with a 1.5% beef extract solution, pH 9.75, containing 0.5% Tween 80. Tween 80 was shown to enhance recovery of the bacteriophages, bacteria, and parasites. Giardia cysts were efficiently eluted (71%) and could be reconcentrated by low-speed centrifugation and purified by sucrose density gradient flotation at a final recovery of 52%. Legionella pneumophila cells were eluted at 64% and were further concentrated by low-speed centrifugation at an overall recovery of 55%. C. perfringens spores and coliphages were eluted at efficiencies of 82 and 86%, respectively, and reconcentrated with minimal loss by a detergent–protein flotation method. Poliovirus was eluted at 93% and reconcentrated at 78% efficiency by organic flocculation.Key words: drinking water, microorganisms, detection, virus.
Cellulase production in Trichoderma reesei immobilized with polymeric fibrous carriers
Authors: Kumakura Minoru , Kanno Setsuko , Nisizawa Kazutoshi
Published: November 2009

Trichoderma reesei mycelia were immobilized on polymeric fibrous carriers covered with various polymers, using a radiation polymerization technique. The mycelia were firmly attached to the surface of the fibril of the carrier covered with hydrophobic polymers. Cellulase production was in some cases higher by immobilized mycelia than by free mycelia and was affected by the chain structure of the polymer.Key words: Trichoderma reesei, immobilization, radiation, cellulase, fibril.
Mitotic mapping in linkage group V of Aspergillus niger based on selection of auxotrophic recombinants by Novozym enrichment
Authors: Debets Alfons J. M. , Swart Klaas , Bos Cees J.
Published: November 2009

This paper describes a procedure which allows the quantitative selection of auxotrophs of the fungus Aspergillus niger by enzymatic killing of immobilized germinating prototrophic conidiospores. We have applied this procedure to linkage analysis on the basis of mitotic crossing-over in this fungus. Starting with a heterozygous diploid strain, we could select auxotrophic homozygous diploid recombinants quantitatively. We estimated the frequency of crossing-over after correction for clonal distribution of recombinants, and localized four auxotrophic markers as well as the centromere on chromosome V of this fungus. The Novozym enrichment procedure proved to be useful in genetic analysis and for the construction of recombinant genotypes in the case of closely linked auxotrophic markers. The detemination of gene order and the estimation of distances on the basis of benomyl-induced recombinant haploid segregants may lead to incorrect conclusions. Genetic analysis on the basis of homozygous recombinants, however, can provide reliable estimates of map distances.Key words: Aspergillus niger, chromosome mapping, mitotic crossing-over, Novozym enrichment, auxotrophic recombinants.
Intestinal microflora of the newborn rat as related to mammary, faecal, and vaginal Staphylococci strains isolated from the dam
Authors: Brunel A. , Gouet P.
Published: November 2009

To determine the relative importance of maternal microflora (faeces, vagina, and teats) in the contamination of newborn rats, strains of staphylococci from six different families (dam + litter) were isolated. These strains were identified, and by means of numerical profiles analyzed for their degree of similarity for each litter and (or) biotope. The staphylococci strains found in the gut of the newborn rat originated first from the teats and thereafter from the faeces. Concomitant observation of some identical strains, however, suggested a certain degree of similarity between these two maternal biotopes in this animal.Key words: intestinal microflora, newborn, dam, staphylococci, numerical taxonomy.
Skin reaction to lipids from avirulent strain Shibaura of Leptospira interrogans serovar copenhageni
Authors: Arimitsu Yoshiko , Moribayashi Atsuko , Goto Norihisa
Published: November 2009

Sonically disrupted cells from avirulent strain Shibaura of Leptospira interrogans serovar copenhageni induced a skin reaction characterized by infiltration of polymorphonuclear leukocytes (PMN) associated with some edema in guinea pigs. To determine the substance inducing infiltration of PMN, lipids of avirulent strain Shibaura were extracted with chloroform – methanol – water after washing with acetone. The lipids comprised 28% of the dry weight of the cell. When the lipids were further separated into water–methanol and chloroform fractions, the most severe PMN infiltration of all samples was seen in the skin inoculated with extract recovered from the chloroform fraction. Neutral and polar lipids were detected after thin-layer chromatography of the chloroform extract. Neutral lipids were detected as free fatty acids (FFA). Fatty acids contained in polar lipids were mainly palmitic acid and palmitoleic acid, whereas FFA comprised 66.5% oleic acid. Skin reactions consisting of marked edema with mild infiltration of PMN were elicited by FFA. There was no obvious difference between a commercially available FFA mixture and the FFA from avirulent strain Shibaura. These observations suggest that FFA may play some role in the pathogenesis of leptospirosis.Key words: Leptospira interrogans serovar copenhageni avirulent strain Shibaura, polar lipids, free fatty acids, skin reaction.
Intermediary metabolism of Acinetobacter grown on dialkyl ethers
Authors: Modrzakowski Malcolm C. , Finnerty William R.
Published: November 2009

The microbial dissimilation of long-chain dialkyl ethers by Acinetobacter sp. H01-N involved a terminal methyl group oxidation of the dialkyl ether substrates, resulting in the formation of ether oxygen containing fatty acids of corresponding chain length. An internal carbon–carbon scission of the dialkyl ethers resulted in the formation of end-product ether fatty acids and corresponding dicarboxylic acids. Cellular carbon and energy were derived from the subsequent metabolism of the dicarboxylic acids. Dicarboxylic acid oxidation, activation, and identification of cellular dicarboxylic acids indicated dibasic acids as intermediates in the metabolism of dialkyl ethers.Key words: dialkyl ethers, dicarboxylic acids, fatty acids, Acinetobacter.
Immunological differentiation of Penicillium species
Authors: Fuhrmann B. , Roquebert M. F. , Hoegaerden M. Van , Strosberg A. D.
Published: November 2009

Antisera were obtained from a rabbit immunized with Penicillium verrucosum var. verrucosum. These antisera were characterized by immunofluorescence and by indirect enzyme-linked immunosorbent assay for their reactivity with 44 strains of moulds. Antigenically, P. verrucosum var. verrucosum (subgenus Penicillium) appears to be similar to strains belonging to subgenus Furcatum, but strongly different from Penicillium frequentans (subgenus Aspergilloides). Specific absorption of antibodies to antigens confirmed the existence of similar biochemical structures on Penicillium frequentans, Aspergillus versicolor, and Aspergillus fumigatus. Immunological procedures may thus significantly contribute to refine the taxonomic classification of moulds.Key words: Penicillium, immunological differentiation.
Nucleotide sequence of the murE gene of Escherichia coli
Authors: Tao Jing-Song , Ishiguro Edward E.
Published: November 2009

The nucleotide sequence of the murE gene encoding the diaminopimelic acid adding enzyme of Escherichia coli is reported. The coding region consisted of 1413 base pairs and was separated from the ftsI (penicillin-binding protein 3) gene by 61 base pairs. The deduced primary structure of MurE comprised 471 amino acid residues with a molecular mass of 50.6 kilodaltons.Key words: Escherichia coli, murE, peptidoglycan synthesis, diaminopimelic acid adding enzyme.
Effects of oxygen on each step of denitrification on Pseudomonas nautica
Authors: Bonin P. , Gilewicz M. , Bertrand J. C.
Published: November 2009

Studies on the effect of oxygen on denitrification have shown that denitrification on Pseudomonas nautica 617 can take place in the presence of oxygen. The enzymes associated with denitrification are affected differently with respect to oxygen concentration. Nitrate reductase was less sensitive toward oxygen than nitrite and nitrous oxide reductases. Nitrate reductase activity was completely blocked at an oxygen concentration greater than 4.05 mg/L, compared with 2.15 and 0.25 mg/L for nitrite and nitrous oxide reductases, respectively. After an aerobic–anaerobic shift, nitrate reductase activity remained unchanged whereas the rate of nitrite reductase activity rose to a value only 20% that of the original rate.Key words: denitrification, oxygen, Pseudomonas.
Kinetic properties of 7α-hydroxysteroid dehydrogenase from Escherichia coli 080
Authors: Prabha V. , Gupta Meenakshi , Gupta K. G.
Published: November 2009

Results on the kinetics of 7α-hydroxysteroid dehydrogenase 7α-HSDH showed that this enzyme could oxidize all bile acids having an –OH group at the C-7 position. Lineweaver-Burk plots showed Michaelis constant (Km) values of 0.83 and 0.12 mM for cholic acid and chenodeoxycholic acid, respectively. The effect of enzyme concentration on the reaction velocity showed a constant increase in the enzyme activity with increase in enzyme-protein concentration. 7α-HSDH was activated by Na+, K+, Ca2+, and Mn2+ ions and by reducing agents having a thiol group (dithiothreitol, 2-mercaptoethanol). Co2+, Hg2+, Fe3+, Mg2+, Zn2+, Ba2+, and Cu2+ ions, chelating agents (potassium oxalate, heparin, EDTA), oxidizing agents (sodium perchlorate, sodium periodate, sodium persulphate), and detergents (Tween 20, Tween 40, Tween 80, Triton X-100, sodium lauryl sulphate) were inhibitory to 7α-HSDH activity.Key words: 7α-hydroxysteroid dehydrogenase, bile acids, NAD+, Escherichia coli 080, enzyme kinetics.
Defects of helicity and motility in the corn stunt spiroplasma, Spiroplasma kunkelii
Authors: Lee I.-M. , Davis R. E.
Published: November 2009

Serum-free medium LD59 was used for primary isolation of Spiroplasma kunkelii (corn stunt spiroplasma) from diseased corn plants from Mississippi. Several strains were cloned in triplicate from one primary pure culture. Some of the strains were helical in cell shape, some were nonhelical, and some were partially helical, consisting of helical and nonhelical regions in the same cell. All helical strains except one (strain I-15) exhibited flexional and rotational motility in broth culture. Partially helical strains exhibited rotational movement in helical regions only. Nonhelical cells exhibited only flexional motility. These three morphological types produced three colony types on medium LD59 solidified with 0.8% agar. Nonhelical strains produced minute "fried egg" colonies (≤ 0.2 mm in diameter after 20 days incubation), while partially helical strains produced small colonies with granular centers surrounded by satellite colonies. Strains with normal helicity in general produced large, uniformly diffuse colonies (up to 2 mm), but one helical strain (I-15) appeared to be nonmotile in broth culture and to exhibit little translational motility in agar medium, accounting for development of minute granular colonies (about 0.2 mm in diameter). All new strains were serologically closely related to known strains of S. kunkelii, but polyacrylamide gel electrophoresis analysis of membrane proteins revealed minor differences. This is the first report of nonhelical strains of S. kunkelii and of helical strains with apparent impairment in translational motility.Key words: Spiroplasma kunkelii, nonhelical spiroplasmas, Mollicutes.
Serum-free media for cultivation of spiroplasmas
Authors: Lee I.-M. , Davis R. E.
Published: November 2009

Serum-free media that contained bovine serum albumin and lipids (fatty acids, cholesterol, phosphatidic acid, and phospholipids) to replace serum were formulated for the culture of some fastidious strains of corn stunt spiroplasma, Spiroplasma kunkelii. These media also supported good growth of other spiroplasmas, including epiphytic, entomopathogenic, and phytopathogenic strains. The growth rates attained in these serum-free media were comparable to those in media which contained serum. The serum-free broth and agar media were of major importance for culture of several fastidious strains of corn stunt spiroplasma because the serum-containing media supported little, if any, of their growth. Colonies of these fastidious strains were readily formed on serum-free agar media in aerobic, candle jar, and anaerobic environments, but were not readily formed on the serum-containing media. The serum-free media were less subject to deterioration during storage or incubation, and the growth-supporting capacity of serum-free media diminished more slowly than that of serum-containing media.Key words: Spiroplasma kunkelii, Spiroplasma citri, Mollicutes, Mycoplasma spp. culture, entomopathogens.