Despite the global importance of Capsicum species, there is limited information on the indigenous endomycorrhizal fungal association in this crop. Therefore, the diversity and colonization patterns of arbuscular mycorrhizal fungi (AMF) in roots of Naga King chilli (Capsicum chinense) were assessed during pre-flowering, flowering and fruit ripening growth stages under a sub-tropical shifting cultivation system of North Eastern India. All the roots examined had AMF colonization and the presence of Paris-type arbuscular mycorrhizal morphology is reported for the first time in C. chinense. A total of 11 AMF spore morphotypes were isolated from both field and trap culture soils. Maximum AMF spore density and root colonization were recorded during the pre-flowering and flowering stages, respectively. The influence of Funneliformis geosporum, individually or in combination with Pseudomonas fluorescens and Azotobacter chroococcum, on growth and yield of C. chinense, was evaluated in a pot experiment using sterilized and non-sterilized soils. The application of AMF and P. fluorescens to sterilized soil significantly increased the growth, flower and fruit production, and nutrient content of C. chinense. The highest growth rates and yields of C. chinense in non-sterilized soils were achieved when AMF was combined with both P. fluorescens and A. chroococcum. The results of the current study indicate the value of applying microorganisms to improve plant growth and performance in chillies. One of the mechanisms for this could be the facilitated assimilation of nutrients promoted by AMF and bacterial bioinoculants.

Pseudomonas fluorescens strain D7 (P. f. D7; NRRL B-18293) is a root-colonizing bacterium that inhibits downy brome (Bromus tectorum L. BROTE) growth. Before commercialization as a biological control agent, strain D7 must be tested for host plant specificity. Agar plate bioassays in the laboratory and plant–soil bioassays in a growth chamber were used to determine the influence of P. f. D7 on germination and root growth of 42 selected weed, cultivated or native plant species common in the western and midwestern United States. In the agar plate bioassay, all accessions of downy brome were inhibited by P. f. D7. Root growth of seven Bromus spp. was inhibited an average of 87% compared with that of controls in the agar plate bioassay. Root growth of non-Bromus monocots was reduced by 0 to 86%, and only 6 out of 17 plant species were inhibited 40% or greater. Among all plant species, only downy brome root growth from two accessions was significantly inhibited by P. f. D7 in plant–soil bioassays (42 and 64%). P. f. D7 inhibited root growth and germination in agar plate bioassays more than in plant–soil bioassays. Inhibition in plant–soil bioassays was limited to downy brome, indicating promise for P. f. D7 as a biocontrol agent that will not harm nontarget species.

“Pesta” is a granular, extruded product made from a cereal grain flour and any biological control agent. A strain of Pseudomonas fluorescens, BRG100, which is a pathogen of green foxtail, has been formulated into a Pesta product. P. fluorescens BRG100 survived processing best in oat flour, and the addition of 20% (wt/wt) maltose extended the shelf life of the product to more than 32 wk. Field studies of 8-wk duration showed that a Pesta product containing BRG100 suppressed green foxtail emergence by as much as 90%. An optimally formulated and processed Pesta product has potential for the biocontrol of green foxtail.

In 2010, 7/44 (16%) reported foodborne outbreaks in Finland were linked with raw beetroot consumption. We reviewed data from the national outbreak registry in order to hypothesize the aetiology of illness and to prevent further outbreaks. In the seven outbreaks, 124 cases among 623 respondents were identified. Consumption of raw beetroot was strongly associated with gastrointestinal illness (relative risk 8·99, 95% confidence interval 6·06–13·35). The illness was characterized by sudden onset of gastrointestinal symptoms; the median incubation time was 40 min and duration of illness 5 h. No common foodborne pathogens or toxins were found in either clinical or beetroot samples, but all tested beetroot samples were of poor quality according to total bacterial counts. Beta-haemolytic Pseudomonas fluorescens was detected in several beetroot samples but its effect on human health is unknown. No outbreaks were reported after the Finnish Food Safety Authority Evira advised against serving raw beetroot in institutional canteens.

We investigated the role of an entomogenic gut bacterium Pseudomonas fluorescens on larval development and survival of Culex vishnui Theobald, the mosquito vector of Japanese encephalitis, which breeds exclusively in rice field water in tropical regions. The bacterium could be isolated from the midguts of third and fourth instars of the mosquito. Pseudomonas fluorescens strain 1 (Ps1) was identified as the one vital to C. vishnui larval survival. The phenotypic characteristics of this strain are described. As part of the study, antibiotics were used to cure C. vishnui larvae of Ps1; thus cured larvae did not survive when subsequently reared in sterile or antibiotic-treated rice field water or tap water. In contrast, 93.3–100% of cured larvae developed into normal adults when subsequently reared either in unsterile or in sterile rice field water or in tap water containing Ps1 bacteria (5 × 103 ml). Thus the elimination of Ps1 from breeding water could be used as a strategy to suppress the mosquito growth, as part of an innovative approach to control Japanese encephalitis.

Pseudomonas fluorescens is a normal inhabitant of the soil rhizosphere. The use of genetically altered strains of P. fluorescens in bioremediation has led to the need for effective monitoring of such cells released into the environment. In this study, we present data on the persistence in soil of P. fluorescens harboring gfp (green fluorescent protein) or lux (bioluminescence) genes. Comparisons were made between strains marked chromosomally and strains carrying these markers on a plasmid. Overall effects of plasmid carriage on culturability were also examined. Sterile soil microcosms were inoculated with washed cells to a final concentration of ca. 106 CFU.g–1 and placed at 5, 23, and 35–37 °C. Samples were taken periodically and examined for culturability and viability, using the substrate responsiveness assay. Our results indicated no significant loss of culturability at 5 and 23 °C for a period of over one year. In contrast, cells of P. fluorescens incubated at 35–37 °C entered the viable but nonculturable state within 7 days. All cells labeled with gfp retained fluorescence regardless of culturability, suggesting that the green fluorescent protein can be of value in monitoring the presence of cells following their release to the environment. Because fluorescence was maintained regardless of the cells’ physiological state, this protein may also be an indicator of cell viability.

The effect of different parameters (pH, ultrasonic amplitude and pressure) on the resistance to heat and manothermosonication (MTS) treatments of heat resistant lipase and protease produced by Pseudomonas fluorescens B52 and NCDO 2085, respectively, were studied. Lipase B52 thermoresistance decreases with an increase of pH. However, inactivation by MTS seems to be pH independent. There were only slight increases in the MTS efficiency when increasing pressure at UHT temperatures and the effect of amplitude was different depending on treatment temperature. Protease NCDO 2085, which was very resistant to MTS at 30 °C, was very sensitive to MTS at 76 °C. Increases in applied pressure had no effect on MTS efficiency at 140 °C and its inactivation by MTS was almost temperature independent between 76–109 °C. Data obtained are compared with previous published data and inactivation mechanisms are discussed.

The influence of Glomus intraradices (BEG87) on Pseudomonas fluorescens DF57 in hyphosphere and rhizosphere soil was examined. Cucumis sativus (Aminex, F1 hybrid) was grown in symbiosis with the arbuscular mycorrhizal fungus G. intraradices in PVC tubes, consisting of a central root compartment and two lateral root-free compartments. Two Tn5-luxAB-marked strains of P. fluorescens DF57 were used. Strain DF57-P2, which has an insertion of Tn5[ratio ][ratio ]luxAB in a phosphate starvation-inducible locus, was used as a phosphate starvation reporter. Another lux-tagged strain DF57-40E7, which carries a constitutively expressed luxAB fusion, was used as control for strain DF57-P2 and for measuring the metabolic activity of P. fluorescens DF57. A strain of P. fluorescens DF57, which carries a constitutively expressed gfp gene, was used in studies of attachment between the bacteria and the hyphae. G. intraradices decreased the culturability of P. fluorescens DF57 significantly, both in rhizosphere and hyphosphere soil, whereas the total number of P. fluorescens DF57 measured by immunofluorescence microscopy was decreased in hyphosphere soil only. G. intraradices did not induce a phosphorus starvation response in P. fluorescens DF57, and the metabolic activity of the bacteria was not affected by the fungus after 48 h. P. fluorescens DF57 did not attach to G. intraradices hyphae and was not able to use the hyphae as carbon substrate. The negative effect of G. intraradices on culturability and on number of P. fluorescens DF57 in hyphosphere soil is discussed.

Previous studies demonstrated the role of the O-antigenic side chain of the outer membrane lipopolysaccharides of Pseudomonas fluorescens strain WCS417r in its ability to induce resistance against fusarium wilt disease. The present study compared the colonization of tomato roots (Lycopersicon esculentum Mill.) by P. fluorescens strain WCS417r with that of a mutant of this strain, lacking the O-antigenic side chain of its outer membrane lipopolysaccharides (OA−). Special attention was paid to colonization within root tissues and changes of the root ultrastructure induced by the bacterial strains. Experiments were performed with tomato plants rooted in rock wool and tomato seedlings grown on agar. Numeration of colony-forming units showed that wild-type strain WCS417r colonized the root interior of tomato grown in rock wool to a higher extent than its OA− mutant B4, whereas colonization of the rhizoplane did not differ between the two. Light microscopy observations of cross sections of roots grown on agar showed that (i) colonization of the root interior by both wild-type and OA− mutant was inter- and intracellular, (ii) colonization of the internal root tissues mainly occurred if the Pseudomonas strains were inoculated at sites of lateral root emergence, (iii) the wild type colonized the root interior more frequently than did its OA− mutant. Thickening of the cortical cell walls, in reaction to the bacterial colonization of epidermal or hypodermal cells, or cortical intercellular spaces, suggested that local defence reactions of the plant occurred. Altogether, these results indicate the involvement of the O-antigenic side chain of the outer membrane lipopolysaccharides in the endophytic colonization of the tomato root by P. fluorescens WCS417r, and lead us to hypothesize that induction of disease resistance by strain WCS417r might be related to the extent of colonization of the internal root tissues.