Persistence of a biocontrol Pseudomonas inoculant as high populations of culturable and non-culturable cells in 200-cm-deep soil profiles     

Josef Troxler  Miroslav Svercel  Andreas Natsch  Marcello Zala  Christoph Keel  Yvan Moënne-Loccoz  Geneviève Défago 《Soil biology & biochemistry》2012,44(1):122-129

Little is known about the ecology of soil inoculants used for pathogen biocontrol, biofertilization and bioremediation under field conditions. We investigated the persistence and the physiological states of soil-inoculated Pseudomonas protegens (previously Pseudomonas fluorescens) CHA0 (10⁸ CFU g^?1 surface soil) in different soil microbial habitats in a planted ley (Medicago sativa L.) and an uncovered field plot. At 72 days, colony counts of the inoculant were low in surface soil (uncovered plot) and earthworm guts (ley plot), whereas soil above the plow pan (uncovered plot), and the rhizosphere and worm burrows present until 1.2 m depth (ley plot) were survival hot spots (10⁵–10⁶ CFU g^?1 soil). Interestingly, strain CHA0 was also detected in the subsoil of both plots, at 10²–10⁵ CFU g^?1 soil between 1.8 and 2 m depth. However, non-cultured CHA0 cells were also evidenced based on immunofluorescence microscopy. Kogure's direct viable counts of nutrient-responsive cells showed that many more CHA0 cells were in a viable but non-culturable (VBNC) or a non-responsive (dormant) state than in a culturable state, and the proportion of cells in those non-cultured states depended on soil microbial habitat. At the most, cells in a VBNC state amounted to 34% (above the plow pan) and those in a dormant state to 89% (in bulk soil between 0.6 and 2 m) of all CHA0 cells. The results indicate that field-released Pseudomonas inoculants may persist at high cell numbers, even in deeper soil layers, and display a combination of different physiological states whose prevalence fluctuates according to soil microbial habitats.  相似文献   

Sensitivity of <Emphasis Type="Italic">Eisenia fetida</Emphasis> in comparison to <Emphasis Type="Italic">Aporrectodea caliginosa</Emphasis> and <Emphasis Type="Italic">Lumbricus terrestris</Emphasis> after imidacloprid exposure. Body mass change and histopathology     

Nils Dittbrenner  Hannah Schmitt  Yvan Capowiez  Rita Triebskorn 《Journal of Soils and Sediments》2011,11(6):1000-1010

Purpose  

The use of only one or a few species—representing an entire taxon—in ecotoxicological standard tests poses risk of underestimating the impact of toxicants on the environment. In earthworm ecotoxicity tests, the species Eisenia fetida or Eisenia andrei are commonly used, and there is evidence that these species respond relatively insensitive towards environmental pollution. With the present study, we wanted to evaluate the risk of underestimating effects of the insecticide imidacloprid in soil organisms by comparing E. fetida with two other earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) regarding their sensitivities towards soil contaminated with this widely used insecticide.  相似文献   

The Use of Mineral Oil in Potato Protection: Dynamics in the Plant and Effect on Potato Virus Y Spread     

Manphool S. Fageria  Sébastien Boquel  Gaetan Leclair  Yvan Pelletier 《American Journal of Potato Research》2014,91(5):476-484

The focus of this study was to evaluate two mineral oils (Superior 70 and Vazyl-Y) in reducing the seasonal spread of Potato Virus Y (PVY). Three concentrations of oil (0, 5, and 10 L ha^?1 of Superior 70; 0, 7.5, and 15 L ha^?1 of Vazyl-Y) and three spray regimes for both oils (every 3–4, 7, and 10–11 days) were tested. Two weeks after top-kill, two tubers from each of 49 plants free of virus at emergence were harvested from treatment plots, sprouted, and tested for PVY with enzyme-linked immunosorbent assay (ELISA). Results revealed that in the case of Superior 70, PVY spread in mineral oil treated plots ranged from 2.1 to 12.2 %, while in the control plots it ranged from 20.4 to 37.7 % across three cultivars. In the case of Vazyl-Y, PVY spread in mineral oil treated plots ranged from 2.1 to 26.5 %, while in the control plots it ranged from 49.9 to 85.7 % across three cultivars. These data show that there was a significant reduction in PVY due to spray of mineral oils. In addition, mineral oil was quantified in plants from the Superior 70 treated and the control plots to understand the dynamics of mineral oil during the season. While there was little to no oil measured in the leaves at the early stages of plant growth, a considerable amount of mineral oil was detected close to plant maturity. A basic model of the concentration of oil in the treated foliage was formulated to confirm our understanding of the factors at play. The model could explain from 50 to 90 % of the variation in oil content observed in the field. Plant growth and size are important factors affecting oil content in mineral oil treated foliage.  相似文献   

Molecular characterization and PCR detection of a nitrogen-fixing Pseudomonas strain promoting rice growth     

M. Sajjad Mirza  Samina Mehnaz  Philippe Normand  Claire Prigent-Combaret  Yvan Moënne-Loccoz  René Bally  Kauser A. Malik 《Biology and Fertility of Soils》2006,43(2):163-170

Nitrogen-fixing plant growth-promoting rhizobacteria (PGPR) from the genus Pseudomonas have received little attention so far. In the present study, a nitrogen-fixing phytohormone-producing bacterial isolate from kallar grass (strain K1) was identified as Pseudomonas sp. by rrs (16S ribosomal RNA gene) sequence analysis. rrs identity level was high with an uncharacterized marine bacterium (99%), Pseudomonas sp. PCP2 (98%), uncultured bacteria (98%), and Pseudomonas alcaligenes (97%). Partial nifH gene amplified from strain K1 showed 93% and 91% sequence similarities to those of Azotobacter chroococcum and Pseudomonas stutzeri, respectively. The effect of Pseudomonas strain K1 on rice varieties Super Basmati and Basmati 385 was compared with those of three non-Pseudomonas nitrogen-fixing PGPR (Azospirillum brasilense strain Wb3, Azospirillum lipoferum strain N4 and Zoogloea strain Ky1) used as single-strain inoculants. Pseudomonas sp. K1 was detected in the rhizosphere of inoculated plants by enrichment culture in nitrogen-free growth medium, which was followed by observation under the microscope as well as by PCR using a rrs-specific primer. For both rice varieties, an increase in shoot biomass and/or grain yield over that of noninoculated control plants was recorded in each inoculated treatment. The effect of Pseudomonas strain K1 on grain yield was comparable to those of A. brasilense Wb3 and Zoogloea sp. Ky1 for both rice varieties. These results show that nitrogen-fixing pseudomonads deserve attention as potential PGPR inoculants for rice.  相似文献   

Stereoisomeric distribution of 3-mercaptohexan-1-ol and 3-mercaptohexyl acetate in dry and sweet white wines made from Vitis vinifera (Var. Sauvignon Blanc and Semillon)     

Tominaga T  Niclass Y  Frérot E  Dubourdieu D 《Journal of agricultural and food chemistry》2006,54(19):7251-7255

The enantiomeric distribution of 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA) in Vitis vinifera wines was determined by combining two techniques: specific purification of volatile thiols from the wines using p-hydroxymercuribenzoate and separation of the chiral molecules by gas-phase chromatography on a cyclodextrin capillary column. The R and S enantiomer ratios of these two thiols in dry white Sauvignon blanc and Semillon wines are approximately 30:70 for A3MH and 50:50 for 3MH. However, in sweet white wines made from grapes affected by "noble rot" due to the development of Botrytis cinerea on ripe grapes, the proportion of the R and S forms of 3MH is in the vicinity of 30:70. During alcoholic fermentation, a change in the ratio of the two enantiomers of 3MH in dry white wines was observed. At the beginning of fermentation (around density 1.08), the S form represented over 60%; then, at lower density, as fermentation proceeded, the enatiomeric ratio approached 50:50. The ratio of the two 3MHA enantiomers remained constant throughout fermentation. On the contrary, the distribution of the two 3MH enantiomers changed very little during fermentation of the botrytized sweet wines. The perception thresholds for the R and S forms of 3MH in hydroalcoholic model solution are similar (50 and 60 ng/L). These two enantiomers have quite different aromas: The R form is fruitier, with a zesty aroma reminiscent of grapefruit, while the S form smells more of passion fruit. The perception thresholds of the R and S enantiomers of 3MHA are slightly different (9 and 2.5 ng/L). The less odoriferous R form is reminiscent of passion fruit, while the S form has a more herbaceous odor of boxwood.  相似文献   

Use of the script concordance approach to evaluate clinical reasoning in food-ruminant practitioners     

Dufour S  Latour S  Chicoine Y  Fecteau G  Forget S  Moreau J  Trépanier A 《Journal of veterinary medical education》2012,39(3):267-275

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Comparison of sandy soils suppressive or conducive to ectoparasitic nematode damage on sugarcane   总被引：1，自引：0，他引：1  

Rimé D  Nazaret S  Gourbière F  Cadet P  Moënne-Loccoz Y 《Phytopathology》2003,93(11):1437-1444

ABSTRACT Two South African sandy soils, one suppressive and the other conducive to ectoparasitic nematode damage on monoculture sugarcane, were compared. Analysis of field transects indicated that the suppressive soil displayed a comparatively higher population of the weak ectoparasite Helicotylenchus dihystera, whose predominance among ectoparasitic nematodes is known to limit yield loss caused by more virulent phytonematodes. Soil type was identical at both sites (entisols), but the suppressive soil had a higher organic matter content and a lower pH, which correlated with H. dihystera population data. In contrast, microclimatic differences between the two field sites were unlikely to be responsible for the suppressive or conducive status of the soils, as shown in a greenhouse experiment. The two soils exhibited a bacterial community of the same size but with different genetic structures, as indicated by automated ribosomal intergenic spacer analysis (RISA). The number of culturable fluorescent pseudomonads was higher for the conducive soil, probably because extensive root damage caused by ectoparasitic nematodes favored proliferation of these bacteria. This study shows that apparently small differences in soil composition between fields located in the same climatic area and managed similarly can translate into contrasted nematode communities, ectoparasitic nematode damage levels, and sugarcane yields.  相似文献   

Veterinary Dentistry for the Small Animal Technician          下载免费PDF全文

Yvan Dumais 《The Canadian veterinary journal. La revue veterinaire canadienne》2001,42(8):654

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Evolution of burrow systems after the accidental introduction of a new earthworm species into a Swiss pre-alpine meadow   总被引：2，自引：0，他引：2  

Y. Capowiez  A. Pierret  P. Monestiez  L. Belzunces 《Biology and Fertility of Soils》2000,31(6):494-500

 The unintentional introduction of a new earthworm species (Aporrectodea nocturna) into a Swiss pre-alpine meadow resulted in a great increase in earthworm density in the newly colonized area (386 m^–2) compared with the density observed in the natural area (273 m^–2) where an earthworm community was already present. To investigate the impact of this introduction on the burrow systems, eight soil cores (length 25 cm, diameter 16 cm) were taken (four in the colonized area and four in the natural area) and analysed with computer-assisted X-ray tomography. The resulting images were processed to obtain the 3D-skeleton reconstructions of the earthworm burrow systems. Due to high variability in these burrow systems, only slight differences were observed between the two areas. The total burrow length and the mean burrow lengths tended to be greater in the colonized area. Moreover, the distribution of pore numbers with depth showed different patterns with a maximum for depths between 10 cm and 15 cm in the colonized area and a maximum for depths between 20 cm and 25 cm in the natural area. These differences may have been related to: (1) the particular behaviour of A. nocturna, which was observed to cast at the surface in this site, and (2) the predominance of juvenile earthworms around the colonization front. These differences were sufficient to create significant effects on the continuity of the burrow systems (assessed by the number of different pathways between virtual horizontal planes) for the two areas. The colonized area was characterized by a greater pore continuity, which could have resulted in enhanced transfer properties. Received: 2 July 1999  相似文献   

Cell therapy of alpha-sarcoglycan null dystrophic mice through intra-arterial delivery of mesoangioblasts   总被引：1，自引：0，他引：1  

Sampaolesi M  Torrente Y  Innocenzi A  Tonlorenzi R  D'Antona G  Pellegrino MA  Barresi R  Bresolin N  De Angelis MG  Campbell KP  Bottinelli R  Cossu G 《Science (New York, N.Y.)》2003,301(5632):487-492

Preclinical or clinical trials for muscular dystrophies have met with modest success, mainly because of inefficient delivery of viral vectors or donor cells to dystrophic muscles. We report here that intra-arterial delivery of wild-type mesoangioblasts, a class of vessel-associated stem cells, corrects morphologically and functionally the dystrophic phenotype of virtually all downstream muscles in adult immunocompetent alpha-sarcoglycan (alpha-SG) null mice, a model organism for limb-girdle muscular dystrophy. When mesoangioblasts isolated from juvenile dystrophic mice and transduced with a lentiviral vector expressing alpha-SG were injected into the femoral artery of dystrophic mice, they reconstituted skeletal muscle in a manner similar to that seen in wild-type cells. The success of this protocol was mainly due to widespread distribution of donor stem cells through the capillary network, a distinct advantage of this strategy over previous approaches.  相似文献