Rhizoplane colonisation of peas by Rhizobium leguminosarum bv. viceae and a deleterious Pseudomonas putida.

Pseudomonas putida strain A313, a deleterious rhizosphere bacterium, reduced pea nitrogen content when inoculated alone or in combination with Rhizobium leguminosarum bv. viceae on plants in the presence of soil under greenhouse conditions. When plants were grown gnotobiotically in liquid media, mixed inocula of A313 and rhizobia gave a higher proportion of small evenly distributed nodules when compared with a single rhizobial inoculation.

Efficiency of procedures for induction and cultivation of Pseudomonas syringae pv. pisi L-form.

The L-form of Pseudomonas syringae pv. phaseolicola has been proved to induce resistance to bean halo blight. Various procedures were tested to induce the L-form of Pseudomonas syringae pv.

Diversity of endophytic bacterial populations and their interaction with Xylella fastidiosa in citrus plants.

Citrus variegated chlorosis (CVC) is caused by Xylella fastidiosa, a phytopathogenic bacterium that can infect all Citrus sinensis cultivars. The endophytic bacterial communities of healthy, resistant, and CVC-affected citrus plants were studied by using cultivation as well as cultivation-independent techniques. The endophytic communities were assessed in surface-disinfected citrus branches by plating and denaturing gradient gel electrophoresis (DGGE).

Analysis of Endophytic Bacterial Communities of Potato by Plating and Denaturing Gradient Gel Electrophoresis (DGGE) of 16S rDNA Based PCR Fragments.

The diversity of endophytic bacterial populations of potato (Solanum tuberosum cv Desirée) was assessed using a combination of dilution plating of plant macerates followed by isolation and characterization of isolates, and direct PCR-DGGE on the basis of DNA extracted from plants. The culturable endophytic bacterial communities detected in potato stem bases as well as in roots were in most cases on the order 103 to 105 CFU g?1 of fresh plant tissue. Dilution plating revealed that a range of bacterial types dominated these populations.

Indirect immunofluorescence colony staining method for detecting bacterial pathogens of tomato.

An indirect immunofluorescence colony staining method was developed for the detection of important seed-borne bacterial pathogens of tomato. The method involves the use of specific antiserum for initial binding of target bacteria and visualization of positive colonies with a commercially available secondary antiserum conjugated with FITC and observed under a fluorescence microscope. The indirect method is especially suitable for laboratories, seed companies, and quarantine stations which have no facilities for conjugation of primary antiserum.

Natural incidence of endophytic bacteria in pea cultivars under field conditions.

Pea plants grown in the field were used to study the natural incidence of endophytic bacteria in the stem. Eleven pea cultivars at the flowering stage were screened for the presence of endophytic bacteria using a printing technique with surface disinfested stem cross-sections on 5% Trypticase Soy Agar (TSA). Five cultivars showed colonization.

Spatio-temporal distribution of naturally occurring Bacillus spp. and other bacteria on the phylloplane of soybean under field conditions.

Bacterial populations were surveyed on phylloplane of field-grown soybean every 20 days in southern Buenos Aires, Argentina. The crop was disease-free and no pesticides were applied. Out of 523 bacterial isolates (mainly Gram positive bacteria) from upper and lower leaves, 134 of them were Bacillus spp.

Comparative analysis of antibiotic resistance, immunofluorescent colony staining, and a transgenic marker (bioluminescence) for monitoring the environmental fate of rhizobacterium.

Field releases of the wild-type plant growth-promoting rhizobacterium Pseudomonas fluorescens 89B-27, its bioluminescent derivative GEM-8 (89B-27::Tn4431), and a spontaneous rifampin-resistant variant estimating the wild-type population. Seed and root samples were taken 0, 7, 14, 21, or 28, 35 or 42, and 70 days after planting in each year and processed for enumeration by spiral plating or immunofluorescent colony staining (IFC). In both years, the populations of 89B-27, R34, and GEM-8, as measured by IFC, were not significantly different (P > 0.

Immunomagnetic separation of Erwinia carotovora subsp. atroseptica from potato peel extracts to improve detection sensitivity on a crystal violet pectate medium or by PCR.

Immunomagnetic separation (IMS) procedures for the selective separation of Erwinia carotovora subsp. atroseptica from potato peel extract were optimized for the recovery of target and removal of non-target bacteria. A streptomycin-resistant strain of Erw.

A novel cell surface polysaccharide in Pseudomonas putida WCS358, which shares characteristics with Escherichia coli K antigens, is not involved in root colonization.

Previously we have shown that flagella and the O-specific polysaccharide of lipopolysaccharide play a role in colonization of the potato root by plant growth-promoting Pseudomonas strains WCS374 and WCS358. In this paper, we describe a novel cell surface-exposed structure in Pseudomonas putida WCS358 examined with a specific monoclonal antibody. This cell surface structure appeared to be a polysaccharide, which was accessible to the monoclonal antibody at the outer cell surface.

Polymerase chain reaction for verification of fluorescent colonies of Erwinia chrysanthemi and Pseudomonas putida WCS358 in immunofluorescence colony staining.

The potential of polymerase chain reaction (PCR) for verifying the identity of colonies stained by the immunofluorescence colony-staining (IFC) procedure was investigated. Using primers directed against conserved sequences of the pectate lyase-genes coding for isozymes PLa, PLd and PLe of Erwinia chrysanthemi, the authors confirmed the identity of 96% of 20 fluorescent target colonies, punched from IFC-stained samples with pure cultures. In pour plates with mixtures of Erw.

Polyclonal Antisera To Distinguish Strains and Form Variants of Photorhabdus (Xenorhabdus) luminescens.

In this study antisera against Photorhabdus luminescens strains were prepared for the first time. P. luminescens is a bacterial symbiont of entomopathogenic nematodes belonging to the genus Heterorhabditis.

Verification of ELISA results by immunomagnetic isolation of antigens from extracts and analysis with SDS-PAGE and western blotting, demonstrated for Erwinia spp. in potatoes.

Isolation of antigens on immunomagnetic beads and subsequent analysis with SDS-PAGE and Western blotting (immunomagnetic isolation-Western blotting (IMI-WB)) was used to verify positive ELISA results for Erwinia chrysanthemi and Erw. carotovora subsp. atroseptica in potato peel extracts.

Use of fluorochromes for direct observation of microorganisms associated with wheat roots.

The use of several fluorochromes and staining methods was tried out for observation of microorganisms on the surface of wheat roots sampled from soil. Good contrast between fluorescence of microorganisms and fluorescence of root and soil structures was obtained after successive staining of roots with coriphosphine (1:2000, 15 min), congo red (1:10 000, 10 min), and acridine-orange (1:10 000, 2 min).