bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical and chemical control of released microorganisms at field sites
Authors: Donegan Katherine , Seidler Ramon , Matyac Carl
Published: May 2010

An important consideration in the environmental release of a genetically engineered microorganism is the capability for reduction or elimination of microorganism populations once their function is completed or if adverse environmental effects are observed. In this study the decontamination treatments of burning and biocide application, alone and in combination with tilling, were evaluated for their ability to reduce populations of bacteria released on the phylloplane. Field plots of bush beans (Phaseolus vulgaris), sprayed with the bacterium Erwinia herbicola, received the following treatments: control; control + till; burn; burn + till; Kocide (cupric hydroxide); Kocide + till; Agri-Strep (streptomycin sulfate); and Agri-Strep + till. Leaves and soil from the plots were sampled −1, 1, 5, 8, 12, 15, 19, and 27 days after application of the decontamination treatments. Burning produced a significant reduction in the number of E. herbicola, whereas tilling, alone or in combination with the biocide treatments, stimulated a significant increase in E. herbicola populations, which persisted for several weeks. The individual treatments of the biocides, Kocide and Agri-Strep, produced a rate of decline in E. herbicola populations that did not significantly differ from that of the control treatment. Key words: decontamination, risk control, field release, genetically engineered microorganisms.
Temperature response of an associative N2-fixing Pseudomonas species in pure culture
Authors: Chan Yiu-Kwok
Published: May 2010

The growth rate and nitrogenase (acetylene reduction) activity of a pseudomonad isolated from the rhizosphere of the grass species Deschampsia caespitosa were investigated in the 0–35 °C temperature range. Growth was detected from 5 to 30 °C with or without provision of fixed N and its optimum growth temperature was about 25 °C, establishing its psychrotrophic response to temperature. Maximum nitrogenase activity was also found at about 25 °C. Low but significant nitrogenase activity was detected below 15 °C. This organism was confirmed to be a microaerobic diazotroph and it was sensitive to a dissolved O2 concentration of ca. 12 μM. It is probably dependent on the appropriate environment in the rhizosphere of the host plant in order to persist with sustained nitrogenase activity during cold and dormant periods. Key words: nitrogen fixation, Pseudomonas, psychrotroph, temperature.
Extracellular release of protease III (ptr) by Escherichia coli K12
Authors: Díaz-Torres María R. , Dykstra Christine C. , Claverie-Martín Félix , Kushner Sidney R.
Published: May 2010

Escherichia coli strains carrying the protease III structural gene (ptr) on a plasmid secreted the protein into the growth medium. Plasmid-encoded β-lactamase and chloramphenicol acetyl transferase, which served as periplasmic and cytoplasmic markers during cell fractionation, were not released into the growth medium. There appeared to be some strain dependence on the proficiency of the secretion system. Protease III was not detectably processed upon export through the outer cell membrane. Key words: protein secretion, protease III, Escherichia coli, signal sequence, growth medium.
Comparison of the pathogenicity of three species of coagulase-negative Staphylococcus in a mouse model with and without a foreign body
Authors: Ferguson K. P. , Lambe Jr. D. W. , Keplinger J. L. , Kalbfleisch J. H.
Published: May 2010

Staphylococcus schleiferi, Staphylococcus lugdunensis, and Staphylococcus epidermidis produce a high incidence of abscesses in a mouse model with an implanted foreign body. We investigated the significance of the foreign body in this process. Fourteen strains of S. schleiferi, S. epidermidis, and S. lugdunensis were tested in our model. A preadhered foreign body was implanted into one mouse group, followed by injection of a test strain. Another group received injection without implant. Abscesses were assessed at 7 days; foreign bodies and infected tissues were cultured. The percent of samples that developed abscesses or were culture positive was compared for each strain. Nearly all mice infected with S. schleiferi developed abscesses and were culture positive. The foreign body made no difference in abscess formation for three of four S. schleiferi but increased the incidence of both organism recovery and abscess for three of five S. epidermidis. The foreign body enhanced abscess formation for four of five S. lugdunensis, with all five strains yielding significantly more culture recovery. Although the pathogenicity of nine strains was increased by the foreign body, five strains yielded high abscess and culture recovery rates that were not enhanced by its presence. Key words: foreign body, Staphylococcus lugdunensis, Staphylococcus schleiferi.
Serine proteinase of Renibacterium salmoninarum digests a major autologous extracellular and cell-surface protein
Authors: Rockey D. D. , Turaga P. S. D , Wiens G. D. , Cook B. A. , Kaattari S. L.
Published: May 2010

Renibacterium salmoninarum is a pathogen of salmonid fish that produces large amounts of extracellular protein (ECP) during growth. A proteolytic activity present in ECP at elevated temperatures digested the majority of the proteins in ECP. This digestion was also associated with the loss of ECP immunosuppressive function. In vitro activity of the proteinase in ECP was temperature dependent: it was not detected in an 18-h digest at 4 and 17 °C but became readily apparent at 37 °C. Proteinase activity was detected at bacterial physiological temperatures (17 °C) in reactions incubated for several days. Under these conditions, digestion of partially purified p57, a major constituent of ECP and a major cell-surface protein, yielded a spectrum of breakdown products similar in molecular weight and antigenicity to those in ECP. This pattern of digestion suggests that most of the immunologically related constituents of ECP are p57 and its breakdown products. The proteolytic activity was sensitive to phenylmethylsulfonyl fluoride, methanol, and ethanol and to 10-min incubation at temperatures above 65 °C. Electrophoretic analysis of the proteinase on polyacrylamide gels containing proteinase substrates indicated the native form to be 100 kDa or greater. The enzyme was active against selected unrelated substrates only when coincubated with a denaturant (0.1% lauryl sulfate) and (or) a reducing agent (20 mM dithiothreitol). Key words: Renibacterium salmoninarum, proteinase, hemagglutinin, antigen F, bacterial kidney disease.
Pseudomonas cepacia and Pseudomonas putida as winter wheat inoculants for biocontrol of Rhizoctonia solani
Authors: Freitas J. Renato de , Germida James J.
Published: May 2010

Pseudomonas cepacia R55 and R85 and Pseudomonas putida R104, antagonistic towards plant pathogenic fungi in vitro, were assessed as seed inoculants for winter wheat (cv. Norstar) grown in a growth chamber in soil infested with Fusarium solani or Rhizoctonia solani isolate AG-1, AG 2-1, or AG-3. Infestation of soil with R. solani AG-1 or AG 2-1 reduced root dry weight of uninoculated plants by 62 and 78%, respectively, whereas R. solani AG-3 or F. solani had no effect on plant biomass. Pseudomonad inoculants increased (relative to plants subjected to disease) the winter wheat root dry weight by 92–128% and shoot dry weight by 28–48% in the soil infested with R. solani AG-1. The shoot material of all plants inoculated with pseudomonads also had significantly (P < 0.05) higher total Fe contents than the uninoculated treatment in the R. solani AG-1 infested soil. Pseudomonas cepacia R55 produced the highest (P < 0.01) total Fe contents in the shoots, but it had no effect on N and P content. Pseudomonas cepacia R85 significantly increased total N (P < 0.05) and total P (P < 0.01) of wheat shoots, and P. putida R104 increased the percentage (P < 0.05) and (or) total P content (P < 0.01) in the soil infested with R. solani AG-1. Pseudomonas cepacia R85 also significantly (P < 0.05) increased wheat shoot biomass in R. solani AG-3 infested soil. All three pseudomonads produced fluorescent siderophores when cultured in a low-iron medium. These results suggest an in situ antibiosis activity of three fluorescent pseudomonad strains towards phytopathogenic fungi and suggest that the plant growth response was probably due to protection against damage caused by R. solani. Key words: biocontrol, pseudomonads, Rhizoctonia solani, winter wheat, siderophores.
Survival and injury of Escherichia coli, Campylobacter jejuni, and Yersinia enterocolitica in stream water
Authors: Terzieva Silva I. , McFeters Gordon A.
Published: May 2010

Experiments were done to describe the survival and injury of three strains each of enteropathogenic Escherichia coli, Yersinia enterocolitica, and Campylobacter jejuni in agricultural surface water. Bacterial suspensions within membrane diffusion chambers were immersed in two large vessels of stream water that were held at 6 and 16 °C and changed daily. The results of daily plate counts, using selective and nonselective media, revealed some variation among strains and genera. Injury increased rapidly in all of the bacteria examined during an initial 4-day period of population stability. Bacterial persistence was generally prolonged at 6 °C, while the occurrence of injury was directly related to temperature. However, both survival and injury in C. jejuni were less dependent on temperature, while Y. enterocolitica displayed the greatest survival at both 6 and 16 °C. These results suggest that surface water in the temperate zone might serve as a persistent vehicle for the transmission of these enteropathogenic bacteria between animals and humans. Key words: survival, injury, water.
Relationships between the abilities of streptomycetes to decolorize three anthron-type dyes and to degrade lignocellulose
Authors: Pasti Maria B. , Crawford Don L.
Published: May 2010

Fourteen Streptomyces strains known to degrade lignocellulose were screened for their ability to decolorize three anthron-type dyes: Remazol Brilliant Blue R (RBBR), blue poly(vinylamine) sulfonate – anthraquinone dye (Poly B-411), and red poly(vinylamine) sulfonate – anthrapyridone dye (Poly R-478). The relationships between efficiency of dye decolorization and capacity to attack lignocellulose were examined. Good correlation was found between lignocellulose weight losses observed during previous solid-state fermentation assays and the ability to decolorize RBBR and Poly B-411. A poor correlation was observed between Poly R-478 decolorizing activity and lignocellulose-degrading ability. The presence of corn stover lignocellulose in the culture broth enhanced decolorization of the dye by all but one of the strains. The enhancement was thought to involve the increased production of extracellular peroxidases by cultures growing on lignocellulose. The results on oxidation of the three dyes by a commercial horseradish peroxidase indicate that RBBR and Poly B-411 are suitable substrates for analyzing production of peroxidases by Streptomyces spp., while no decolorization of Poly R-478 was observed under the conditions used. However, Poly R-478 decolorizing activity of the Streptomyces may reflect the activity of other enzymes involved in the complex process of lignocellulose degradation. Key words: Streptomyces, lignocellulose, degradation, dye, decolorization.
Cross hybridization of plasmid and genomic DNA from aromatic and polycyclic aromatic hydrocarbon degrading bacteria
Authors: Foght J. M. , Westlake D. W. S.
Published: May 2010

Forty-three bacterial strains were collected from various environmental and commercial sources and their ability to degrade polycyclic aromatic hydrocarbons (PAHs) was confirmed using the criteria of growth, mineralization, and oxidation. Undigested genomic DNA from these strains was blotted by Southern transfer to replicate membranes, which were probed either with purified plasmids (e.g., TOL and NAH7, associated with toluene and naphthalene degradation, respectively) or with genomic DNA from the other strains. The isolates were grouped according to hybridization and PAH-degradation results. One group of eight strains grew on naphthalene vapors as sole carbon source and hybridized with archetypical NAH plasmids. Another group of six isolates mineralized phenanthrene but could not grow on naphthalene, and their cryptic plasmids hybridized with Pseudomonas sp. HL7b, which degrades a wide range of PAHs. The remaining isolates, which could not grow on naphthalene but mineralized and (or) oxidized a variety of PAHs, hybridized with neither the pure plasmids nor heterologous genomic DNA, implying that their PAH-degradative genes were significantly dissimilar. This suggests that using TOL or NAH plasmids to probe an environmental population might reveal toluene- or naphthalene-degradative genes but would underestimate the occurrence of PAH-degradative genes. We suggest that a suite of probes would be necessary to evaluate the PAH-degradation potential of a mixed population. Key words: polycyclic aromatic hydrocarbons, degradative plasmids, NAH plasmid, TOL plasmid, hybridization.
HT-2 toxin, roridin A, T-2 toxin, and verrucarin A mycotoxins inhibit carbon dioxide production by Kluyveromyces marxianus
Authors: Koshinsky Heather A. , Hannan Patrick J. , Khachatourians George G.
Published: May 2010

The effects of four trichothecene mycotoxins on carbon dioxide production by a yeast, Kluyveromyces marxianus, were examined. Carbon dioxide release rate was inhibited by 10% in less than 25 min or 50% in less than 65 min by 0.0625, 0.125, 1.25, and 12.5 μg/mL of verrucarin A, roridin A, T-2 toxin, and HT-2 toxin, respectively. Lower concentrations did not affect carbon dioxide release rate within 160 min. Individually, neither 0.625 μg/mL T-2 toxin nor 0.000125 μg/mL roridin A alters carbon dioxide production. When combined at these concentrations, the two trichothecenes interact synergistically to inhibit carbon dioxide release rate by 50% within 60 min. In the case of grains contaminated with mycotoxin mixtures this synergistic interaction may raise concerns about safe-exposure conditions. Key words: carbon dioxide, Kluyveromyces marxianus, synergism, trichothecene mycotoxins.
A comparative study on the biology of Cryptosporidium sp. from guinea pigs and Cryptosporidium parvum (Apicomplexa)
Authors: Tilley Michael , Upton Steve J. , Chrisp Clarence E.
Published: May 2010

Cryptosporidum sp. from guinea pigs and C. parvum were compared morphologically, electrophoretically, and for the ability to infect suckling mice. Oocysts from guinea pigs measured 5.4 × 4.6 (4.8–5.6 × 4.0–5.0) μm and had a shape index (length/width) of 1.17 (1.04–1.33). Oocysts of C. parvum were similar and measured 5.2 × 4.6 (4.8–5.6 × 4.2–4.8) μm with a shape index of 1.16 (1.04–1.33). All suckling mice inoculated with oocyts of C. parvum became infected, whereas most, but not all, mice fed oocysts of the guinea pig isolate also became infected. However, mice inoculated with oocysts from guinea pigs produced on average 100-fold fewer oocysts by day 7 postinoculation than did mice infected with C. parvum, and the resulting infections were sparse and patchy along the ileum. Electrophoretic profiles were similar, but 125I surface labeling of outer oocyst wall proteins revealed striking differences between the two isolates. Cryptosporidium parvum had a wide molecular size range of 125I-labeled bands, whereas C. sp. from guinea pigs had a banding pattern clustered between 39 and 66 kDa, with a smaller number of bands >100 kDa. Key words: Cryptosporidium parvum, coccidia, Apicomplexa, guinea pig, mouse.
Effects on soybean seed yield by members of 123 serocluster and USDA 110 in the greenhouse and in soils low in indigenous Bradyrhizobium japonicum
Authors: McLoughlin T. J. , Alt S. G. , Gonzalez R. G. , Romero-Severson J.
Published: May 2010

USDA 123spc and USDA 110str were inoculated on three soybean cultivars in a pot experiment in the greenhouse. USDA 110str yielded 33% more seed than USDA 123spc (P < 0.01). In a low-Bradyrhizobium soil (10 cells/g) at Arlington, WI, three members of the 123 serocluster (USDA 123spc, NJ2-lastr, and I-123spc), USDA 110, and USDA 138 were inoculated at a rate of 1 × 108 cells/2.5-cm row on two soybean cultivars. The inoculum strains formed 100% of the nodules. There was no difference (P < 0.05) in seed yield between any of the inoculum strains on either cultivar. In a low-Bradyrhizobium (102 cells/g), low-N soil, in Georgia, USDA 110, USDA 110str, and two members of the 123 serocluster (USDA 123spc and NJ2-lastr) were inoculated at an inoculum rate of 1 × 108 cell/2.5-cm row on two soybean cultivars. Plots were fertilized with 156 kg of N ha−1, or no N was applied. Serogroup 110 formed 59–90% of the nodules and serocluster 123 formed 48–82% of the nodules on the cultivars. There were no differences in seed yield between the inoculum strains, except that on cv. Gordon with added N, USDA 110 resulted in higher seed yield than USDA 123spc. The uninoculated control plots with cv. Braxton (without added N) also had a better seed yield (P < 0.05) than plots inoculated with USDA 123spc. In summary, inoculation with USDA 110str resulted in higher soybean seed yield than inoculation with USDA 123spc under greenhouse conditions, but not always under field conditions. Key words: Bradyrhizobium japonicum, field trials, seed yield.
Bacterioplankton in the Seine River (France): impact of the Parisian urban effluent
Authors: Garnier Josette , Servais Pierre , Billen Gilles
Published: May 2010

Bacterial abundance and biomass were studied in April, July, and October 1989 at 13 stations along 300 km of the course of the river Seine, including Paris and its suburbs. Monthly investigations were carried out at five stations downstream from Paris where the river receives the effluent of an important waste water treatment plant (Achères). As a result of an input of allochthonous bacteria from the effluent of the plant, an increase in bacterial abundance and biomass was observed below Achères (from about 5 × 109 to 15 × 109 cells L−1 and from 100 to 750 μg C L−1). This was followed by a rapid decrease. The allochthonous bacteria comprised a high proportion of large bacteria, which disappeared at a much higher rate than the small bacteria (0.0366 vs. 0.0125 h−1). Paradoxically, these large bacteria grew at a rate twice that of the smaller cells in culture experiments (0.129 vs. 0.065 h−1 in June and 0.118 vs. 0.071 h−1 in October). These large bacteria must therefore be subjected to intense losses (grazing, sedimentation, etc.). Higher rates of discharge of the river, i.e., a shorter residence time of the water masses, appeared to transmit the Achères signal farther, leading to faster transport of the bacterial populations. Key words: bacterioplankton ecology, size fractions, river ecosystem.
Cytochrome composition and oxygen-dependent respiration-driven proton translocation in Wolinella curva, Wolinella recta, Bacteroides ureolyticus, and Bacteroides gracilis
Authors: Han Yeong-Hwan , Smibert Robert M. , Krieg Noel R.
Published: May 2010

The membrane fractions of the microaerobically grown type strains of Wolinella curva, Wolinella recta, Bacteroides ureolyticus, and Bacteroides gracilis contained membrane-bound cytochrome b, cytochrome c, and CO-binding cytochrome c. Soluble cytochrome c and CO-binding cytochrome c were also present. Although B. gracilis is oxidase negative, it possessed cytochrome c. With H2 or formate as the electron donor, proton efflux from anaerobic cells occurred upon addition of a pulse of oxygen. With formate as the electron donor, the H+/O ratios of W. curva, W. recta, B. ureolyticus, and B. gracilis were 0.75, 1.66, 2.06, and 2.04, respectively. With H2 as the electron donor, the H+/O ratios of W. curva, B. ureolyticus, and B. gracilis were 1.25, 1.97, and 2.36, respectively. Proton translocation was inhibited by the protonophore carbonylcyanide m-chlorophenylhydrazone. The results confirm that the organisms are not anaerobes but are microaerophiles capable of respiring with oxygen. Key words: cytochrome, proton, Wolinella, Bacteroides, microaerophile.
Epiphytic populations of Pseudomonas syringae on barley
Authors: Georgakopoulos Dimitrios G. , Sands David C.
Published: May 2010

The epiphytic populations of Pseudomonas syringae were monitored on 23 barley entries planted in the field in four replications during the summer of 1986, and on six selected entries during the summer of 1987, from the second-leaf stage until senescence. Populations were initially low (0–3 log colony-forming units (cfu) per leaf) in all but one entry; they generally increased throughout the season, and at the end they reached 3–7 log cfu/leaf. Significant differences among the average epiphytic populations were found in the 1986 trial; only one entry, however, had a significantly different average population in the 1987 trial. The slopes of population increase were also compared: significant differences were observed in 1986 but not in 1987. In addition to epiphytic population counts, the percentage of ice nucleation active bacteria was determined in the population isolated from each leaf sample, and averaged throughout the season for each entry. Significant differences were observed in 1986 and in 1987. When the entries were ranked according to their average epiphytic population and compared between the two experiments, they were found to be very similar. The same was not true for the other parameters studied in the experiment. Key words: epiphytic populations, ice nucleation, barley.
Competition among Rhizobium leguminosarum bv. phaseoli strains for nodulation of common bean
Authors: George Maria Luz C. , Robert Françoise M.
Published: May 2010

Six effective Rhizobium leguminosarum bv. phaseoli strains were examined for nodulation competitiveness on common bean (Phaseolus vulgaris L.), using all possible two-strain combinations of inoculum. Nodule occupancy was determined with strain-specific fluorescent antibodies. The strains were divided into three groups according to their overall competitive abilities on pole bean cv. Kentucky Wonder and bush bean cv. Bountiful. Strains TAL 182 and TAL 1472 were highly competitive (greater than 70% nodule occupancy); strains KIM-5, Viking 1, and CIAT 899 were moderately competitive (approximately 50% nodule occupancy); and strain CIAT 632 was poorly competitive (less than 5% nodule occupancy). The competitiveness of the six strains was similar on the two host cultivars. The proportion of competing strains in the inoculum influenced the nodule occupancy of the highly competitive and moderately competitive strains, but not that of the poorly competitive strain. Two outstanding strains (TAL 182 and TAL 1472) were identified as ideal model strains for molecular and genetic studies on nodulation competitiveness. Key words: Rhizobium, Phaseolus vulgaris, nodulation, competition.
Plasmids in Listeria monocytogenes and other Listeria species
Authors: Peterkin Pearl I. , Gardiner Mary-Ann , Malik Naeem , Idziak Edmund S.
Published: May 2010

One hundred and twenty-two food, clinical, and veterinary strains of Listeria monocytogenes were examined for the presence of plasmids. Twenty-five (20%) contained plasmids, which varied from 1.3 to 66 MDa in size. Of 10 strainsof other Listeria species (L. innocua, L. ivanovii, L. welshimeri, L. seeligeri, L. grayi, and L. murrayi) examined, seven (70%) contained plasmids, varying from 38 to 53 MDa. No strains with multiple plasmids were found. Plasmids of identical size were isolated from related strains in some, although not all, cases. The presence of a plasmid in a strain was not related to phenotypic characters of known extrachromosomal inheritance. Key words: plasmid, Listeria spp., Listeria monocytogenes.
Relative persistence capacity of BCG substrains in mouse spleen. Computerized statistical analysis. Multiple comparison
Authors: Lugosi Laszlo
Published: May 2010

The relative persistence capacity in mouse spleen of 10 and 9 BCG substrains from liquid and dried vaccines, respectively, was evaluated in two studies. Recoverable BCG colony counts from mouse spleen were determined at given days on solid medium in the two studies during a period of 1–360 and 1–345 days, respectively, after the intravenous BCG vaccination, performed with two different viable units. From 36 000 (study 1) and 21 600 (study 2) recoverable BCG colony counts, 180 and 108 mean relative persistence capacity values were estimated to test the residual virulence during the follow-up time, using computerized statistical analysis. The early and late trends of mean relative persistence capacity of the BCG substrains in mouse spleen were tested by linear regression analysis and analysis of variance and covariance; then with ranked adjusted group mean relative persistence capacity, Gabriel's simultaneous test procedure was performed for multiple comparison to diminish type 1 error in statistical inference and in objective interpretation of the experimental results. The associations of the ranked mean relative persistence capacity of the BCG substrains at the different sacrifice days of mice were also analyzed by Kendall's test of concordance. The early, late, and overall relative persistence capacity reflects the residual virulence of the BCG substrains and provides information on the required protective efficacy (immunogenicity) and adverse reactions (reactogenicity), allowing the appropriate vaccination dose, expressed in viable units of the substrain used, to be determined. Key words: BCG substrains, residual virulence, relative persistence in mouse spleen, multiple comparison.
Isolation of Frankia from nodules of Trevoa trinervis: ultrastructural characterization
Authors: Carrasco Alicia , Schwencke Jaime , Caru Margarita
Published: May 2010

Root nodules obtained from Trevoa trinervis and its actinomycete Frankia were studied by electron microscopy. The microsymbiont was found in the cortical cells and it exhibits the typical actinomycetal structures: septate hyphae and symbiotic vesicles. Using the double-layer technique, two Frankia strains were isolated from the nodules. In vitro these strains exhibit morphological characteristics considered specific to the genus Frankia, i.e., hyphae, Frankia vesicles, and polymorphic sporangia. Key words: Frankia, actinomycetes, Trevoa.
Biodegradation of soil humic acids by Streptomyces viridosporus
Authors: Kontchou C. Yanze , Blondeau Roland
Published: May 2010

Biodegradation of soil humic acids by Streptomyces viridosporus ATCC 39115 growing in a mineral salts – glucose medium was demonstrated. This biodegradation accompanies bacterial growth and is, therefore, presumed to be a primary metabolic activity, but humic acids were not used as the sole source of carbon. This bacterial activity was enhanced when cells were shaken and within a pH range of 6.5–8.5. In further experiments, the relative abilities of S. viridosporus to mineralize [14C]melanoidin, used as synthetic humic acid, were also established. In contrast to the white rot fungus Phanerochaete chrysosporium, another microorganism exhibiting humic acid degrading activity at acidic pH, poor extracellular activities were found in culture medium of S. viridosporus, and veratryl alcohol does not result in increased humic acid degradation. In spite of some peroxidase activity measured in culture filtrates and analyzed by polyacrylamide gel electrophoresis, the humic acid degrading system of S. viridosporus, in these experimental conditions, seems to be cell associated. Key words: humic acid biodegradation, melanoidin mineralization, Streptomyces viridosporus, cell-bound humic acids.
Biochemical characterization and time-course analysis of Lymantria dispar nuclear polyhedrosis virus with monoclonal antibodies
Authors: Yu Cao-Guo , Ma Michael , Ding Tsuey , Hetrick Frank , Hsu Hei-Ti
Published: May 2010

Hybridoma cell lines secreting monoclonal antibodies (MAbs) specific to a 31 000 molecular weight viral protein or a 31 000 molecular weight polyhedrin protein of Lymantria dispar nuclear polyhedrosis virus (LdNPV) were developed. The two polypeptides were shown to be different by comparing their amino acid compositions. Immuno-electron microscopy was used to verify specific binding of the MAbs to their respective targets. Specific MAbs were used to develop an ELISA procedure to monitor the development of LdNPV virus and polyhedrin in vivo. Results indicated that in hemolymph of larvae fed 106 polyhedral inclusion bodies, the concentration of virus began to increase 16 h after inoculation and continued to increase for the next 5 days. By 36 h, the concentration of polyhedrin increased and was maintained at a high level in the later stages of infection. One-third of this group of infected larvae survived the infection. In these individuals, the concentrations of virus and polyhedrin declined to a low level 5 days after infection. This suggests the presence of a host mechanism for clearing the virus from the hemolymph. Key words: infection mechanism, monoclonal antibody, in vitro immunization, Lymantria dispar nuclear polyhedrosis virus, ELISA.
Sheen formation and growth response of groundwater bacteria to reduced oxygen concentrations during incubation of M-Endo medium
Authors: Shirey James J. , Bissonnette Gary K.
Published: May 2010

In vitro pure-culture studies were conducted to assess growth and sheen formation of groundwater bacteria on M-Endo medium incubated under reduced oxygen concentrations (0, 4, 8, 12, and 16%). Coliform and noncoliform bacteria were isolated from 17 untreated, rural groundwater supplies on M-Endo medium. All 16 coliform isolates tested were capable of sheen formation at oxygen concentrations of 4% or greater, yet some of these same isolates (Enterobacter aerogenes, Enterobacter cloacae, and Hafnia alvei) were either unable to grow or failed to produce a metallic sheen when incubated under strict anaerobiosis. Approximately 70% of the 21 noncoliform isolates examined exhibited growth inhibition at oxygen concentrations of 8% or less. The growth of a false-positive coliform isolate of Serratia fonticola was inhibited when incubated under reduced oxygen concentrations of 16% or less. Our findings suggest that the selectivity of M-Endo medium, and resultant inhibition of noncoliforms and false-positive coliforms, is enhanced by incubation in the absence of oxygen. However, the failure of strict anaerobiosis to permit detection of total coliforms such as Hafnia and Enterobacter spp. may compromise the reliability of this technique for evaluating the sanitary quality of some waters. On the other hand, oxygen concentrations of 4, 8, 12, and 16% permitted adequate sheen development of all coliforms tested while inhibiting some noncoliforms. Key words: coliforms, anaerobiosis, groundwater, sheen formation.
Detection and disinfection of pathogens in storm-generated flows
Authors: O'shea Marie L. , Field Richard
Published: May 2010

The disease-producing potential of recreational waters is currently estimated through the use of certain bacterial indicators that are believed to be positively correlated with the presence of fecal contamination. In general, these indicators and their recommended limiting values have been adopted for use from existing standard methods for the analysis of sanitary waste water. However, no indicator currently in use today exists solely in the feces of man and not also elsewhere, e.g., in soils, vegetation, and the feces of animals. Storm-water runoff is often rich in bacteria originating from these nonhuman sources and can contain high densities of indicator bacteria; however, existing epidemiological studies of recreational waters receiving storm-water runoff have reported little correlation between current indicator densities and the incidences of swimming illnesses. In addition, microbial analyses of storm-water runoff have revealed a predominance of nonenteric disease-causing bacteria and viruses that have been linked to respiratory illnesses and skin infections. Fecal-based indicators in use today provide no information on the risks resulting from body contact with these nonenteric pathogens. Consequently, for receiving waters containing discharges that originate primarily from separate storm drainage systems, current bacterial indicators are ill suited to accurately assess the water's total illness-producing capabilities. This paper briefly reviews the development of current bacterial standards and evaluates their adoption in the field of storm-water testing. The unique disinfection requirements of storm-generated runoff are discussed, and advanced disinfection practices are reviewed. The need for additional epidemiological studies that address the disease-causing potential of nonhuman and nonenteric pathogens commonly found in storm-water runoff from urban, agricultural, and rural watershed areas is emphasized in order to determine the actual health risks associated with storm water runoff contact. Key words: storm water, disinfection, microorganisms, water-quality indicators.
Transposon Tn5-259 mutagenesis of Pseudomonas cepacia to isolate mutants deficient in antifungal activity
Authors: Jayaswal Radheshyam K. , Fernandez Marcel A. , Visintin Luisa , Upadhyay Ram S.
Published: May 2010

Transposon Tn5-259 was inserted into the chromosome of Pseudomonas cepacia by mating with an Escherichia coli strain harboring a self-mobilizable, temperature-sensitive plasmid, pME12. Data from Southern blots and auxotroph analyses indicated that a single copy of the transposon was inserted in several places into the chromosome of P. cepacia. Among 1500 Tn5-259 transconjugants, only one mutant was found to be defective in the production of an antifungal compound, pyrrolnitrin. In addition, this mutant lost its ability to antagonize fungal phytopathogens. Using flanking DNA of the mutated gene as a probe, we have isolated four overlapping cosmid clones from a genomic library of P. cepacia. However, we were unable to complement the mutant because of difficulty in mobilizing the cosmids from E. coli to P. cepacia. Key words: Pseudomonas cepacia, antifungal activity, transposon mutagenesis, antagonism, biocontrol.
In situ colonization of polyvinyl chloride, brass, and copper by Legionella pneumophila
Authors: Bezanson Gregory , Burbridge Susan , Haldane David , Marrie Thomas
Published: May 2010

A sampling device (Robbins device) was used to expose brass, copper, and polyvinyl chloride plugs to potable water contaminated by Legionella pneumophila serogroup 1. Plugs were removed at approximately 1-week intervals and cultured. The colonization rates were polyvinyl chloride, 70; copper, 31; and brass, 25%. Quantitative cultures revealed that polyvinyl chloride was most heavily colonized, whereas brass was least colonized. We conclude that materials used in plumbing systems are readily colonized by Legionella and that the Robbins device provides a means for testing such materials in an in situ setting. Key words: Legionella, colonization, plumbing materials.
Transformation of Acidiphilium by electroporation and conjugation
Authors: Glenn Anne W. , Roberto Frank F. , Ward Thomas E.
Published: May 2010

Two techniques, electroporation and conjugation, have been used to introduce the RK2-based broad-host-range plasmids pRK415 and pLAFR3 into strains of the bacterial genus Acidiphilium. Using electroporation, cells were also transformed with a series of chimeric plasmids constructed by cloning cryptic Acidiphilium plasmids into the Escherichia coli vector pBR328. Various parameters affecting electroporation were investigaed. Transformation efficiency varied widely with different recipient strains. Growth at an elevated temperature (37 °C) prior to electroporation increased transformation efficiency 10-fold compared with growth at 32 °C. For three strains tested, optimum transformation efficiency was obtained with field strengths of 10–15 kV/cm. Transformation efficiency increased linearly with increasing DNA concentration up to 10 μg/mL. Transformation efficiencies in these experiments ranged up to 104 transformants/μg DNA. Mobilization of pRK415 and pLAFR3 from E. coli strain S17.1 into several Acidiphilium strains was achieved following incubation for 3 h on nutrient agar medium (pH 7.0). Conjugation frequencies in the range of 10−5–10−9 per recipient cell were obtained. Conjugation frequency was also dependent on recipient strain. Key words: acidophilic bacteria, endogenous plasmids, broad-host-range plasmids.
Isolation and characterization of two temperate phages from Lactococcus lactis ssp. cremoris C3
Authors: Jarvis Audrey W. , Parker Vaughan R. , Bianchin Moana B.
Published: May 2010

Lactococcus lactis ssp. cremoris C3 was shown to contain two prophages, C3-T1 and C3-T2, both inducible bymitomycin C. The phages were morphologically indistinguishable, having an isometric head (55 nm), a noncontractile tail (142 nm), and a distinctive base plate. The phages C3-T1 and C3-T2 were differentiated from one another by restriction endonuclease analysis of their DNA, and genome sizes of 37.8 (C3-T1) and 32.5 kb (C3-T2). Southern blot DNA hybridization suggested a maximum homology between the phage genomes of 50%. Phage C3-T1 was propagated and the phage obtained was designated C3-TIℓ. Phage C3-T2 was not propagated despite tests with a large number of possible indicator strains. Restriction enzyme analysis of phage C3-T1ℓ genome yielded a 37.8-kb circular restriction map. The packaging site (pac) and site of integration into the bacterial chromosome (att) were located and an EcoRI DNA fragment containing the att site was cloned. Only one C3-T1 att site was present in the C3 chromosome. No homology was detected between DNA from C3-T1ℓ and DNA from lytic phages commonly isolated from cheese wheys. Key words: lactococcal phages, temperate phages, lysogeny, evolution.
Purification and properties of extracellular endoxylanases from alkalophilic thermophilic Bacillus sp.
Authors: Dey Devyani , Hinge Jyoti , Shendye Abhay , Rao Mala
Published: May 2010

An alkalophilic thermophilic Bacillus sp. (NCIM 59) isolated from soil produced two types of cellulase-free xylanase at pH 10 and 50 °C. The two enzymes (xylanase I and II) were purified to homogeneity by ethanol precipitation followed by Bio-Gel P-10 gel filtration and preparative polyacrylamide gel electrophoresis. The molecular weights of xylanase I and II were estimated to be 35 000 and 15 800, respectively, by sodium dodecyl sulfate gel electrophoresis. The enzymes exhibited immunological cross-reactivity and were glycoproteins. They had similar temperature (50–60 °C) and pH (6) optima. Both xylanases were stable at 50 °C at pH 7 for 4 days. However, xylanase I was comparatively more stable than xylanase II at 60 °C. The isoelectric points of xylanase I and II were 4 and 8, respectively. The apparent Km values, using xylan as substrate, were 1.58 and 3.5 mg/mL, and Vmax values were 0.0172 and 0.742 μmol∙min−1∙mg−1, respectively. Both xylanases were inhibited by N-bromosuccinimide, suggesting the involvement of tryptophan in the active site. The hydrolysis patterns demonstrated that the xylanases were endoenzymes. Xylanase I and II yielded mainly xylobiose, xylotriose, and higher xylooligosaccharides, with traces of xylose from xylan. Key words: cellulase-free xylanase, alkalophilic thermophilic Bacillus sp., enzyme purification, characterization.
Taxonomy of the rhizobia
Authors: Elkan G. H.
Published: May 2010

Extensive cross testing on a relatively few legume hosts led initially to a taxonomic characterization of rhizobia based on bacteria–plant cross–inoculation groups. This has gradually become less acceptable, and has been replaced by taxonomic groupings derived from numerical taxonomy, carbohydrate metabolism, antibiotic susceptiblities, serology, and various molecular techniques. It has long been recognized that there are two distinct groups of rhizobia based on growth rate. The fast-growing genus Rhizobium includes R. leguminosarum, R. meliloti, R. loti, R. galegae, R. tropici, and R. huakuii. The slow-growing genus Bradyrhizobium contains only one recognized species, B. japonicum. Two new genera have been recognized: Azorhizobium, with one recognized species (A. caulinadans), and Sinorhizobium, with two species (S. fredii and S. xinjiangensis). Genetic studies of both the fast- and slow-growing groups show unacceptably wide intrageneric and intergeneric diversity. Although there have been some elegant studies of some of the genetic relationships among rhizobia, overall there has (have) not been the comprehensive study(ies) needed to allow a conclusive taxonomic scheme. Because proposals for revision are accelerating, minimum standards have been proposed by the International Subcommittee for the Taxonomy of Rhizobium and Agrobacterium. Key words: Rhizobium taxonomy, classification of rhizobia, interrelationships of rhizobia.
Rhizobia that nodulate tree legumes: specificity of the host for nodulation and effectiveness
Authors: Turk Dan , Keyser Harold H.
Published: May 2010

Rhizobial specificity, defined in terms of nodulation and nitrogen-fixing effectiveness characteristics of a group of rhizobia on a host legume, serves as a basis for predicting the need to inoculate, selecting species for most probable number plant-infection assays, and preparing rhizobial inoculants suitable for a range of legume species. A series of inoculation experiments were performed under growth room and greenhouse conditions to delineate rhizobial specificity of a variety of tree legumes. Gliricidia sepium, Calliandra calothyrsus, and Leucaena leucocephala nodulated effectively with rhizobia isolated from each of the three genera. With a few exceptions, Sesbania grandiflora and Robinia pseudoacacia nodulated effectively only with rhizobial strains isolated from each genus respectively. A range of specificity was found among species that nodulate with Bradyrhizobium. Whereas Acacia mearnsii nodulated with most strains but fixed N2 effectively with relatively few, Acacia mangium and Lysiloma latisiliqua were specific for both nodulation and effectiveness. Key words: nitrogen fixation, effectiveness, nodulation, rhizobia, tree legumes.
Nitrogen assimilation in the legume root nodule: current status of the molecular biology of the plant enzymes
Authors: Cullimore Julie V. , Bennett Malcolm J.
Published: May 2010

Genes and cDNAs encoding several enzymes in the nitrogen assimilatory pathway have been cloned and characterised from a number of legume species. Molecular studies using these clones have revealed how these genes are regulated to effect changes in the activity of the enzymes in the different cells of the nodule. Current work is addressing the mechanism of the cell-specific expression and metabolic regulation of these genes and is investigating the role of the nitrogen assimilatory enzymes in regulating flux through the nitrogen fixation and assimilation pathways. Key words: legume root nodules, nitrogen assimilatory enzymes, nitrogen metabolism, plant gene expression.
Environmental effects on competition for nodule occupancy between introduced and indigenous rhizobia and among introduced strains
Authors: Thies Janice E. , Bohlool B. Ben , Singleton Paul W.
Published: May 2010

Understanding the impact of environmental variables on interstrain competition is important to ensure the successful use of rhizobial inoculant. In eight inoculation trials conducted at five diverse sites on Maui, Hawaii, equal numbers of three serologically distinct strains of effective, homologous rhizobia in a peat-based inoculant were applied to seeds of soybean, bush bean, cowpea, lima bean, peanut, leucaena, clover, and tinga pea. We studied the influence of environmental variables on interstrain competition between applied and indigenous rhizobia and among the three strains comprising the inoculum. Although temperature and soil fertility were correlated with nodule occupancy by inoculant strains in a few cases, the most significant environmental variable controlling their competitive success was the size of the indigenous rhizobial population. Nodule occupancy was best described (r2 = 0.51, p < 0.001) by the equation y = 97.88 − 15.03(log10(x + 1)), where y is percent nodule occupancy by inoculant rhizobia and x is the most probable number of indigenous rhizobia per gram soil. For each legume, one of the three inoculant strains was a poor competitor across sites. Competition between the other two strains varied between sites, but was infrequently related to environmental variables. Results indicated that competitive strains could be selected that perform well across a range of environments. Key words: competition, rhizobial ecology, inoculation response, competitiveness index.
Genetic diversity in Bradyrhizobium japonicum Jordan 1982 and a proposal for Bradyrhizobium elkanii sp.nov.
Authors: Kuykendall L. D. , Saxena B. , Devine T. E. , Udell S. E.
Published: May 2010

Fourteen randomly selected clones from cosmid libraries of Bradyrhizobium were used as hybridization probes in Southern blot analysis. Seven of the probes used were from strain USDA 83, a group II strain, and the other seven were from strain I-110, a group Ia strain. The 30 strains examined included 9 strains of Rj4-incompatible soybean bradyrhizobia. Considerable polynucleotide sequence dissimilarity between DNA homology groups was evidenced by striking differences in the number of hybridizing bands, except where the probe carried repetitive DNA. Predictable, simple restriction fragment length polymorphism differences were observed only within DNA homology groups. The previous description that 8 of 9 Rj4-incompatible strains belonged to DNA homology group II was verified. The new data, together with many previously documented differences, make it clear that the DNA homology group II organisms should be classified as a new species, for which the name Bradyrhizobium elkanii is proposed, and strain USDA 76 is designated the type strain. The ATCC number for the type strain is 49852. Key words: DNA:DNA hybridization, soybean, nodulation, bacteria, symbiosis, nitrogen fixation, host compatibility.
Surface antigens present on vegetative Rhizobium meliloti cells may be diminished or absent when cells are in the bacteroid form
Authors: Olsen Perry , Collins Mandy , Rice Wendell
Published: May 2010

The results of fluorescent antibody staining of three Rhizobium meliloti strains using three "strain-cross-reactive" and three "strain-specific" monoclonal antibodies indicated that strain-specific antigens present on surfaces of laboratory-cultured vegetative cells were diminished or absent on surfaces of bacteroid cells extracted from alfalfa nodules formed by the respective strains. In contrast, the monoclonal antibody cross-reactive antigens appeared to be generally conserved during the transition from vegetative cells to bacteroids. These results offer a basis for observed reductions or complete loss of capability of some "strain-specific" monoclonal antibodies developed against vegetative Rhizobium cells to detect the strains in nodule squash material by enzyme-linked immunosorbent assay. Key words: Rhizobium, monoclonal antibody, bacteroid, surface antigen, fluorescent antibody.
Synthesis of β-glucans by Bradyrhizobium japonicum and Rhizobium fredii
Authors: Bhagwat Arvind A. , Keister Donald L.
Published: May 2010

Particulate enzyme preparations from Rhizobium and Bradyrhizobium synthesize β-glucans when incubated with uridine diphosphate glucose (UDP-glucose) and a divalent cation. Synthesis of β-1,2-linked glucans in Rhizobium fredii involves the product of the ndvB gene, a 319-kDa membrane protein, which is labeled with [14C]glucose from UDP-[14C]glucose as previously demonstrated in Rhizobium meliloti and Agrobacterium sp. Bradyrhizobium japonicum synthesize β-1,3- and β-1,6-linked glucans of a lower molecular weight than those synthesized by R. meliloti. In comparative experiments, no evidence was found for a protein-bound intermediate in B. japonicum. The ndvB gene of R. fredii was mobilized to B. japonicum and the gene was expressed, as evidenced by appearance of a large membrane protein (ca. 319 kDa) which was labeled with UDP-[14C]glucose in vitro. Key words: soybean, nitrogen fixation, β-glucan, Bradyrhizobium, Rhizobium.