Multiplex PCR method for the detection of human norovirus, Salmonella spp., Shigella spp., and shiga toxin producing Escherichia coli in blackberry, coriander, lettuce and strawberry.

A multiplex PCR method was developed for the simultaneous detection of murine norovirus (MNV-1) as a surrogate for human norovirus (HuNoV) GI and GII, Salmonella spp., Shigella spp., and Shiga toxin producing Escherichia coli (STEC) in fresh produce. The toxicity of the glycine buffer on bacterial pathogens viability was evaluated. The growth of each of the three pathogens (previously stressed) was evaluated at 35 and 41.5 °C in modified buffered peptone water (mBPW) and trypticase soy broth (TSB), supplemented with vancomycin, novobiocin and brilliant green at two concentration levels. The selected conditions for simultaneous enrichment were: 41.5 °C/mBPW/supplemented with 8 ppm vancomycin, 0.6 ppm novobiocin and 0.2 ppm brilliant green. The pathogens and aerobic plate count (APC) growth was evaluated in the enrichment of lettuce, coriander, strawberry and blackberry under the best enrichment conditions. Starting from 1 to 10 CFU/mL, Salmonella reached from 7.63 to 8.91, Shigella 6.81 to 7.76 and STEC 7.43 to 9.27 log CFU/mL. The population reached for the APC was 5.11-6.56 log CFU/mL. Simultaneous detection by PCR was done using designed primers targeting invA, ipaH, stx1 and stx2 genes, and MNV-1. The detection sensitivity was 10-100 PFU for the MNV-1 and 1-10 CFU for each pathogenic bacteria. This protocol takes 6 h for MNV-1 and 24 h for Salmonella spp., Shigella spp., and STEC detection from the same food portion. In total, 200 samples were analyzed from retail markets from Queretaro, Mexico. Two strawberry samples were positive for HuNoV GI and one lettuce sample was positive for STEC. In conclusion, the method developed in this study is capable of detecting HuNoV GI and GII, Salmonella spp., Shigella spp and STEC from the same fresh produce sample.

Elimination of Phytoplasmas in Rubus Mother Plants by Tissue Culture Coupled with Heat Therapy.

Phytoplasmas are plant-pathogenic bacteria that cause a disease in Rubus species which is referred to as Rubus stunt. As phytoplasmas can be spread by vegetative propagation and latency periods of Rubus stunt can be up to one year, the use of pathogen-free Rubus propagation material in plant nurseries is important in order to stop the spread of this disease. Even though heat therapy has been commonly applied against viruses in many plants, its potential for phytoplasma eradication has been much less explored. Here, the efficacy of heat therapy with subsequent tissue culture to eliminate phytoplasmas from infected raspberry and blackberry plants is evaluated. Heat therapy was performed on 25 phytoplasma-infected raspberry and 33 infected blackberry plants, out of which 100 raspberry and 65 blackberry plants were regenerated via subsequent tissue culture. All plants were negative for the presence of phytoplasma DNA by qPCR at the end of cultivation periods of 481 to 565 days for the treated raspberry plants and 231 to 337 days for the treated blackberry plants. These results show the suitability of heat therapy combined with tissue culture as a routine tool to ensure the presence of phytoplasma-free Rubus mother plants in nurseries.

Biotic elicitation as a tool to improve strawberry and raspberry extract potential on metabolic syndrome-related enzymes in vitro.

BACKGROUND: Raspberry and strawberry are high value-added food products that can contribute to human health due to the abundance of polyphenols that they contain. Polyphenols are secondary metabolites and therefore devoted to improve plant adaptation, these polyphenol profile can be induced applying different stimuli, such as certain bacteria. The aim of this study was twofold: (i) to evaluate the ability of two bacterial strains to modulate secondary metabolisms in strawberry and raspberry, and (ii) to explore the ability of plant extracts to modify enzyme activities related to metabolic syndrome. RESULTS: Total phenolic and anthocyanin content was higher in strawberries than in raspberries, despite similar antioxidant capacities. Strawberry extracts performed better on the tested enzymes, except on α-glucosidase inhibition capacity. Bacillus amyloliquefaciens stabilized the effects of extracts at different points in time, and Pseudomonas fluorescens modified plant metabolism after more inoculations (spring) in both species, improving the effects of raspberry extracts on α-glucosidase, COX1, and COX2, and of strawberry on α-amylase and COX1. CONCLUSION: It is good to include these two fruits in the diet because they improve the activity of metabolic syndrome-related enzymes. Applying either strain during plant growth modifies the bioactive profile of the plants, improving the effects of the fruit extracts on human health. © 2018 Society of Chemical Industry.

Effect of edible coatings with essential oils on the quality of red raspberries over shelf-life.

BACKGROUND: The objective of the present work was to develop strategies for increasing the shelf-life of red raspberries (Rubus idaeus L.), by preventing microorganism growth. RESULTS: Fruits coated with alginate plus lemon essential oil (0.2%) or orange essential oil (0.1%) after 15 days of storage had less red skin than the remaining samples. The less red color verified in these samples was also coincident with the lower concentration of anthocyanins at the end of the experiment as well as the lower capacity for scavenging ABTS free radicals or quenching singlet oxygen. Cyanidin and pelargonidin glucosides were found in raspberries fruits. The edible coatings supplemented with the essential oil of orange either at 0.1% or 0.2% were very efficient for controlling yeast and mold growth after 15 days of storage. To control the development of aerobic mesophilic bacteria the use of essential oil of lemon 0.2% and essential oil of orange 0.1% were the most efficient. CONCLUSION: The application of the film improved post-harvest quality of raspberry, since the addition of essential oils of citrus films promoted to the inhibitory effect of fungi and bacteria growth after 15 days of storage, without changing quality parameters. © 2016 Society of Chemical Industry.

Agrobacterium arsenijevicii sp. nov., isolated from crown gall tumors on raspberry and cherry plum.

Two plant-tumorigenic strains KFB 330(T) and KFB 335 isolated from galls on raspberry (Rubus idaeus) in Serbia, and a non-pathogenic strain AL51.1 recovered from a cherry plum (Prunus cerasifera) tumor in Poland, were genotypically and phenotypically characterized. Phylogenetic reconstruction based on 16S rDNA placed them within the genus Agrobacterium, with A. nepotum as their closest relative. Multilocus sequence analysis (MLSA) based on the partial sequences of atpD, glnA, gyrB, recA and rpoB housekeeping genes suggested that these three strains represent a new Agrobacterium species, that clustered with type strains of A. nepotum, A. radiobacter, "A. fabrum" and A. pusense. This was further supported by average nucleotide identity values (<92%) between the whole genome sequences of strain KFB 330(T) and related Agrobacterium species. The major cellular fatty acids of the novel strains were 18:1 w7c (72.8-77.87%) and 16:0 (6.82-8.58%). Phenotypic features allowed their differentiation from closely related species. Polyphasic characterization showed that the three strains represent a novel species of the genus Agrobacterium, for which the name Agrobacterium arsenijevicii sp. nov. is proposed. The type strain of A. arsenijevicii is KFB 330(T) (= CFBP 8308(T) = LMG 28674(T)).

Characterization of in vitro antifungal activities of small and American cranberry (Vaccinium oxycoccos L. and V. macrocarpon Aiton) and lingonberry (Vaccinium vitis-idaea L.) concentrates in sugar reduced fruit spreads.

In this study, cranberry and lingonberry concentrates were added to commercial sugar-reduced fruit spreads (raspberry-Aloe vera, strawberry-guava, and strawberry-lime), and tested for their antifungal activities. Selected strains of the species Absidia glauca, Penicillium brevicompactum, Saccharomyces cerevisiae and Zygosaccharomyces bailii, as well as xerophilic environmental isolates of the genera Penicillium and Eurotium were used for challenge testing. Initially, varying concentrations of synthetic antifungal agents, such as sodium benzoate, potassium sorbate and butyl 4-hydroxybenzoate were tested against these fungi on wort agar containing 31% fructose at different pH values. Subsequently, the experiments were conducted in fruit spreads containing different concentrations of cranberry and lingonberry concentrates. The results of this study demonstrate that these concentrates were able to inhibit growth of visible colonies of xerophilic and non-xerophilic fungi. Cranberry and lingonberry concentrates are interesting candidates for natural preservation against fungal growth in sugar reduced fruit spreads.

Volatile compounds of raspberry fruit: from analytical methods to biological role and sensory impact.

Volatile compounds play a key role in the formation of the well-recognized and widely appreciated raspberry aroma. Studies on the isolation and identification of volatile compounds in raspberry fruit (Rubus idaeus L.) are reviewed with a focus on aroma-related compounds. A table is drawn up containing a comprehensive list of the volatile compounds identified so far in raspberry along with main references and quantitative data where available. Two additional tables report the glycosidic bond and enantiomeric distributions of the volatile compounds investigated up to now in raspberry fruit. Studies on the development and evolution of volatile compounds during fruit formation, ripening and senescence, and genetic and environmental influences are also reviewed. Recent investigations showing the potential role of raspberry volatile compounds in cultivar differentiation and fruit resistance to mold disease are reported as well. Finally a summary of research done so far and our vision for future research lines are reported.

Anthocyanins from fermented berry beverages inhibit inflammation-related adiposity response in vitro.

Increased adiposity has been associated with macrophage infiltration into the adipose tissue which, in turn, leads to obesity comorbidities, including type 2 diabetes. The objective of this study was to evaluate the effect of anthocyanin (ANC)-enriched fractions from blackberry-blueberry beverages on inflammation and adipogenesis in an in vitro model of inflammation mimicking the pathologic interaction between adipocytes and macrophages. Blend ANCs inhibited secretion of nitric oxide (17.5%), tumor necrosis factor-alpha (TNF-α) (89.4%), and phosphorylated-p65 nuclear factor kappa-B (52.1%) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages after 24 h. Blends reduced intracellular fat accumulation (28.2%) when applied during 3T3-L1 adipocyte differentiation and inhibited isoproterenol-induced lipolysis (18.6%) of mature 3T3-L1 cells. In addition, blend ANCs restored adiponectin-blunted gene expression induced by the TNF-α treatment (18.2%) and reduced the glycerol release (15.9%) induced by LPS-induced macrophage-conditioned media (CM) in adipocytes. Furthermore, blends slightly restored the insulin-induced glucose uptake of adipocytes, blunted by the CM treatment. In conclusion, ANCs from blueberry and blackberry dealcoholized fermented beverages are potential inhibitors of inflammation-related adiposity response and sensitizers of insulin signaling in adipocytes.

Population structure and temporal maintenance of the multihost fungal pathogen Botrytis cinerea: causes and implications for disease management.

Understanding the causes of population subdivision is of fundamental importance, as studying barriers to gene flow between populations may reveal key aspects of the process of adaptive divergence and, for pathogens, may help forecasting disease emergence and implementing sound management strategies. Here, we investigated population subdivision in the multihost fungus Botrytis cinerea based on comprehensive multiyear sampling on different hosts in three French regions. Analyses revealed a weak association between population structure and geography, but a clear differentiation according to the host plant of origin. This was consistent with adaptation to hosts, but the distribution of inferred genetic clusters and the frequency of admixed individuals indicated a lack of strict host specificity. Differentiation between individuals collected in the greenhouse (on Solanum) and outdoor (on Vitis and Rubus) was stronger than that observed between individuals from the two outdoor hosts, probably reflecting an additional isolating effect associated with the cropping system. Three genetic clusters coexisted on Vitis but did not persist over time. Linkage disequilibrium analysis indicated that outdoor populations were regularly recombining, whereas clonality was predominant in the greenhouse. Our findings open up new perspectives for disease control by managing plant debris in outdoor conditions and reinforcing prophylactic measures indoor.