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1.
Microbiol Res ; 236: 126467, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32248049

RESUMO

Strains of Xylella fastidiosa subsp. pauca characterized by a specific genotype, the so called sequence type "ST53", have been associated with a severe disease named Olive Quick Decline Syndrome (OQDS). Despite the relevant research efforts devoted to control the disease caused by X. fastidiosa, so far there are no therapeutic means able to cure the infected host plants. As such, the aim of this study was the identification of antagonistic bacteria potentially deployable as bio-control agents against X. fastidiosa. To this end, two approaches were used, i.e. the evaluation of the antagonistic activity of: i) endophytic bacteria isolated from olive trees located in an infected area but showing mild or no symptoms, and ii) Bacillus strains, as they are already known as bio-control agents. Characterization of endophytic bacterial isolates revealed that the majority belonged to different species of the genera Sphingomonas, Methylobacterium, Micrococcus and Curtobacterium. However, when they were tested in vitro against X. fastidiosa ST53 none of them showed antagonistic activity. On the contrary, when strains belonging to different species of the genus Bacillus were included in these tests, remarkable antagonistic activities were recorded. Some B. velezensis strains also produced culture filtrates with inhibitory activity against X. fastidiosa ST53. Taking also into account that two of these B. velezensis strains (namely strains D747 and QST713) are already registered and commercially available as bio-control agents, our results pave the way for further studies aimed at the development of a sustainable bio-control strategy of the OQDS.


Assuntos
Antibiose , Bacillus , Endófitos/isolamento & purificação , Olea/microbiologia , Xylella , Bacillus/metabolismo , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Agentes de Controle Biológico/farmacologia , DNA Bacteriano/genética , Endófitos/genética , Endófitos/metabolismo , Patologia Molecular , Doenças das Plantas/microbiologia , Doenças das Plantas/terapia , Xylella/patogenicidade
2.
J Sci Food Agric ; 100(3): 926-935, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31523827

RESUMO

BACKGROUND: The effects were studied of different inoculation strategies for selected starters -yeasts and lactic acid bacteria (LAB) - used for the fermentation process of two Greek olive cultivars, Conservolea and Kalamàta. The LAB strains applied were Leuconostoc mesenteroides K T5-1 and L. plantarum A 135-5; the selected yeast strains were S. cerevisiae KI 30-16 and Debaryomyces hansenii A 15-44 for Kalamàta and Conservolea olives, respectively. RESULTS: Table olive fermentation processes were monitored by performing microbiological analyses, and by monitoring changes in pH, titratable acidity and salinity, sugar consumption, and the evolution of volatile compounds. Structural modifications occurring in phenolic compounds of brine were investigated during the fermentation using liquid chromatography / diode array detection / electrospray ion trap tandem mass spectrometry (LC/DAD/ESI-MSn ) and quantified by high-performance liquid chromatography (HPLC) using a diode array detector. Phenolic compounds in processed Kalamàta olive brines consisted of phenolic acids, verbascoside, caffeoyl-6-secologanoside, comselogoside, and the dialdehydic form of decarboxymethylelenolic acid linked to hydroxytyrosol, whereas oleoside and oleoside 11-methyl ester were identified only in Conservolea olive brines. CONCLUSION: Volatile profile and sensory evaluation revealed that the 'MIX' (co-inoculum of yeast and LAB strain) inoculation strategy led to the most aromatic and acceptable Kalamàta olives. For the Conservolea table olives, the 'YL' treatment gave the most aromatic and the overall most acceptable product. © 2019 Society of Chemical Industry.


Assuntos
Debaromyces/metabolismo , Microbiologia de Alimentos/métodos , Lactobacillales/metabolismo , Olea/química , Olea/microbiologia , Fenol/metabolismo , Saccharomyces cerevisiae/metabolismo , Fermentação , Frutas/química , Frutas/microbiologia , Humanos , Fenol/análise , Sais/análise , Sais/metabolismo , Paladar
3.
Plant Dis ; 103(12): 3018-3030, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31545699

RESUMO

California produces over 95% of the olives grown in the United States. In 2017, California's total bearing acreage for olives was 14,570 hectares producing 192,000 tons of olives valued at $186.6 million. During the early spring of 2016, unusual leaf and shoot lesions were detected in olive trees from superhigh-density orchards in the Northern San Joaquin and Sacramento valleys of California. Affected trees displayed numerous leaf and shoot lesions developing at wounds created by mechanical harvesters. The 'Arbosana' cultivar was highly affected by the disease, whereas the disease was sporadic in 'Arbequina' and not found in 'Koroneiki' cultivar. Two fungal species, Neofabraea kienholzii and Phlyctema vagabunda, were found to be consistently associated with the disease, and Koch's postulates were completed. Species identity was confirmed by morphology and molecular data of the partial large subunit rDNA, the internal transcribed spacer region, and partial beta-tubulin region. The disease signs and symptoms are described and illustrated.


Assuntos
Ascomicetos , Olea , Folhas de Planta , Brotos de Planta , Ascomicetos/citologia , Ascomicetos/genética , Ascomicetos/fisiologia , California , DNA Fúngico/genética , DNA Ribossômico/genética , Olea/microbiologia , Folhas de Planta/microbiologia , Brotos de Planta/microbiologia
4.
Food Microbiol ; 84: 103250, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31421771

RESUMO

The aim of this study was to evaluate the effects of six selected yeast starters on natural Taggiasca black table fermentations, in different brine solutions. The olives were subjected to fermentation in 8% (w/v) NaCl, 12% (w/v) NaCl and 12% (w/v) NaCl brine solutions with 0.3% (w/v) citric acid and inoculated with selected yeast starter strains belonging to the following species: Candida adriatica 1985, Candida diddensiae 2011, Cyteromyces matritensis 2005, Nakazawaea molendini-olei 2004, Saccharomyces cerevisiae 2046 and Wickerhamomyces anomalus 1960. Samples of brines and olives were analysed in the initial phase, then again after 30 and 120 days of fermentation. The yeast starters survived differently during the first 30 days of brine fermentation, depending on the NaCl concentration. After 120 days of fermentation N. molendini-olei 2004 and C. matritensis 2005 failed in the brines with 12% NaCl, while the yeast starter cultures C. diddensiae 2011, C. adriatica 1985 and W. anomalus 1960 showed the best performances in terms of survival and competitiveness towards wild yeasts of the brines. The physicochemical and sensorial analysis suggest a potential positive role of these yeasts during the debittering process of the Taggiasca table olives. Considering the combination between yeast starters and the fermentation conditions, the best indication occurred with the brines containing 12% NaCl acidified with citric acid.


Assuntos
Fermentação , Olea/microbiologia , Leveduras/metabolismo , Candida/metabolismo , Microbiologia de Alimentos , Saccharomyces cerevisiae/metabolismo , Sais/química
5.
Mol Plant Microbe Interact ; 32(12): 1649-1664, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31425003

RESUMO

Antimicrobial peptides play a pivotal role in the innate immunity of plants. Defensins are cysteine-rich antifungal peptides with multiple modes of action. A novel Oleaceae-specific defensin gene family has been discovered in the genome sequences of wild and cultivated species of a perennial olive tree, Olea europaea. OefDef1.1, a member of this defensin family, potently inhibits the in-vitro growth of ascomycete fungal pathogens Botrytis cinerea and three Fusarium spp. OefDef1.1 rapidly permeabilizes the plasma membrane of the conidial and germling cells of B. cinerea. Interestingly, it induces reactive oxygen species and translocates to the cytoplasm only in the germlings but not in the conidia. In medium containing a high concentration of Na1+, antifungal activity of OefDef1.1 is significantly reduced. Surprisingly, a chimeric OefDef1.1 peptide containing the γ-core motif of a Medicago truncatula defensin, MtDef4, displays Na1+-tolerant antifungal activity. In a phospholipid-protein overlay assay, the chimeric peptide exhibits stronger binding to its phosphoinositide partners than OefDef1.1 and is also more potent in inhibiting gray mold disease on the surface of Nicotiana benthamiana and lettuce leaves than OefDef1.1. Significant differences are observed among the four ascomycete pathogens in their responses to OefDef1.1 in growth medium with or without the elevated concentration of Na1+. The varied responses of closely related ascomycete pathogens to this defensin have implications for engineering disease resistance in plants.


Assuntos
Defensinas , Fusarium , Olea , Defensinas/metabolismo , Defensinas/farmacologia , Fusarium/efeitos dos fármacos , Alface/microbiologia , Olea/imunologia , Olea/microbiologia , Tabaco/microbiologia
6.
Int J Syst Evol Microbiol ; 69(9): 2899-2906, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31274407

RESUMO

A facultative halo-tolerant Aspergillus strain was isolated from olive brine waste, the effluent from the debittering process of table olives. Phenotypic and molecular characteristics showed clearly that the isolate represents a novel species. Based on the source of isolation, the new species has been named Aspergillus olivimuriae. It was found tolerant to high concentrations of NaCl (15 %) or sucrose (60 %) and it exhibits substantial growth under these conditions. Although the new species grew profusely at 37 °C, no growth was observed at 40 °C, conidia en masse were avellaneous on all media. The description of the new species Aspergillus olivimuriae brings the total species of Aspergillus sect. Flavipedes to 15. The type strain of A. olivimuriae sp. nov. is NRRL 66783 (CCF 6208), its whole genome has been deposited as PRJNA498048.


Assuntos
Aspergillus/classificação , Microbiologia de Alimentos , Olea/microbiologia , Filogenia , Sais , Aspergillus/isolamento & purificação , DNA Fúngico/genética , Técnicas de Tipagem Micológica , Pigmentação , Análise de Sequência de DNA , Esporos Fúngicos
7.
Artigo em Inglês | MEDLINE | ID: mdl-31344898

RESUMO

This paper is devoted to the analysis of the impact of changes in olive urban forests affected by Xylella fastidiosa on ecosystem services. The focus is on microclimate and thermal comfort evaluated by two indices: the temperature of equivalent perception (TEP) and the predicted mean vote (PMV), which take into account both microclimate parameters and personal factors (heat resistance of clothing and human activity). The work has been carried out through (i) a qualitative analysis of the potential ecosystem services changes caused by temporary transition from olive groves to uncultivated soil, (ii) a study of the potential change of land use from monumental olive groves to other types of use, and (iii) a quantitative analysis on microclimate impact due to the loss of ecosystem services in two selected neighborhoods located in the Apulia region and chosen due to their proximity to the urban context. The analysis revealed that (i) direct effects on ecosystem services are principally linked with regulation functions and cultural services, (ii) a critical loss of cultural value of monumental olive groves occurred in the two neighborhoods, (iii) such a loss may lead to an increase of TEP and PMV, indicating a decrease of thermal comfort in the whole neighborhoods. Thus, it is necessary to plan the replanting policies of the use of the areas affected by X. fastidiosa not only in terms of agricultural planning but also in terms of landscape, urban planning, and human well-being.


Assuntos
Florestas , Microclima , Olea/microbiologia , Xylella , Cidades , Planejamento de Cidades , Ecossistema , Doenças das Plantas , Temperatura
8.
Food Funct ; 10(6): 3738-3747, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31173024

RESUMO

The present study aimed to evaluate different mates of Candida boidinii and Lactobacillus pentosus strains as starters in green table olive fermentation. Changes in fermentation characteristics as well as changes in the functional properties of the microbial exopolysaccharides (EPS) produced during the process were registered. The in vitro adhesion test demonstrated that most EPS samples could specifically attach ETEC K88. In vitro studies with porcine intestinal cells showed the improved blocking activity of the fimbria (blocking test) when the mutant strain L. pentosus 119-14MT was used alone as a starter. All EPS samples showed the ability to block receptors in the cells (exclusion test) although without differences between starter treatments. In the displacement test, EPS samples failed to remove the pathogen once attached. According to these results, L. pentosus 119-14MT, a high EPS variant, seemed to be the most effective starter improving the anti-adhesive properties of brine EPS and increasing its ability to block the ETEC K88 fimbria. These results illustrate that the anti-adhesive properties of the EPSs produced during the traditional fermentation of olives could be modulated by the use of defined starters. This opens the door to new fermentation processes aimed to produce green table olives as functional food to prevent ETEC diarrhea.


Assuntos
Aderência Bacteriana/efeitos dos fármacos , Candida/metabolismo , Escherichia coli Enterotoxigênica/efeitos dos fármacos , Lactobacillus pentosus/metabolismo , Olea/microbiologia , Polissacarídeos Bacterianos/farmacologia , Sais/química , Animais , Escherichia coli Enterotoxigênica/fisiologia , Infecções por Escherichia coli/microbiologia , Fermentação , Humanos , Intestinos/microbiologia , Polissacarídeos Bacterianos/metabolismo , Sais/farmacologia , Suínos
9.
Plant Dis ; 103(8): 1809-1827, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31232653

RESUMO

In recent decades, the cultivated area and production of nuts and olives have increased, driven by an increasing consumer interest in healthier food. Diseases of almond, pistachio, olive, and walnut crops caused by species belonging to the Botryosphaeriaceae family have caused concern worldwide. Although considerable progress has been made in elucidating the etiology of these diseases, scientific knowledge of other aspects of these diseases is more limited. In this article, we present an overview of the most important diseases caused by Botryosphaeriaceae fungi affecting almond, pistachio, olive, and walnut crops by focusing on ecology and epidemiology, primarily in California and Spain.


Assuntos
Ascomicetos , Nozes , Olea , Doenças das Plantas , Ascomicetos/fisiologia , California , Ecologia , Nozes/microbiologia , Olea/microbiologia , Doenças das Plantas/microbiologia , Espanha
10.
Food Microbiol ; 82: 259-268, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31027782

RESUMO

The aim of this study is to examine the biogeography of the microbial communities associated to the Spanish-style green olive fermentations in the province of Seville (Andalucía, south-western Spain). Also, to understand how microorganisms colonize and persist in non-sterile food fermentations across a specific table olive producing area, i.e. a specific "agroecosystem". The microbial diversity, bacteria and yeast, in 30 ten-ton fermenters of three different fermentations yards (patios) along the olive fermentation was studied. A total of 951 microbial isolates were obtained which were clustered according to their RAPD profile. A total of 376 distinct genotypes were identified, belonging to 57 different microbial species, 41 bacterial and 16 yeast species. Up to 16 bacterial species had not been described before in table olives. Only the species Lactobacillus pentosus showed a ubiquitous presence in all 30 fermenters. Pediococcus parvulus, Lactobacillus collinoides/paracollinoides, Lactobacillus coryniformis, Lactobacillus plantarum, Pichia manshurica and Candida thaimueangensis were found in every patio. Cosmopolitan strains, up to 15, were shared by the three patios and belonged to the species L. pentosus (12 strains), P. parvulus (1), L. collinoides/paracollinoides (1) and P. manshurica (1). To expand our biodiversity analyses to the "regional" level, we have compared our results with those obtained from two previously studied patios of similar characteristics and in the same geographical area. PERMANOVA analysis of the microbial community composition revealed significant differences among different patios in their structure at every fermentation stage. In contrast, SIMPER analyses showed that, as fermentation progressed, the overall dissimilarities among patios were reduced. Discriminant species were identified for each fermentation stage. Among these, L. pentosus and P. parvulus were "eu-constant" species, while L. collinides/paracollinoides and Marinilactibacillus psychrotolerans group were "constant" species that could be considered microbial key taxa based on the occurrence stability index. The characteristic and, presumably, well adapted microbiota associated to the Spanish-style olive fermentations at the specific geographic area described here is a valuable natural resource which should be preserved conveniently. To our knowledge, this is the first study on the microbial biogeography of table olive fermentations, both at the species and strain levels.


Assuntos
Bactérias/isolamento & purificação , Biodiversidade , Reatores Biológicos/microbiologia , Olea/microbiologia , Leveduras/isolamento & purificação , Bactérias/classificação , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Ecossistema , Fermentação , Microbiologia de Alimentos , Variação Genética , Concentração de Íons de Hidrogênio , Lactobacillus/classificação , Lactobacillus/genética , Lactobacillus/crescimento & desenvolvimento , Lactobacillus/isolamento & purificação , Microbiota/genética , Sais , Espanha , Leveduras/classificação , Leveduras/genética , Leveduras/crescimento & desenvolvimento
11.
J Plant Res ; 132(3): 439-455, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30993555

RESUMO

Olive quick decline syndrome (OQDS) is a dangerous plant disease, caused by the bacterium Xylella fastidiosa, which targets olive (Olea europaea). Since field observations suggested that some olive cultivars (i.e. Leccino) were more resistant to OQDS than others (i.e. Cellina di Nardò), the plant defense strategies adopted by olive to contrast X. fastidiosa infection were investigated. In the present study, ELISA and genetic approaches were used to confirm plant infection, while microbial colonization mechanism and distribution in host plant tissues and reactive oxygen species (ROS) levels were examined by light, scanning electron and confocal microscopy analyses. Spectrophotometric and chromatographic techniques were performed to measure secondary metabolites content and qPCR assay was carried out for monitoring plant gene expression variation. Our analysis showed that X. fastidiosa caused accumulation of ROS in Leccino samples compared to Cellina di Nardò. Moreover, the infection induced the up-regulation of defense-related genes, such as NADPH oxidase, some protein kinases, pathogen plant response factors and metabolic enzymes. We also found that Leccino plants enhanced the production of specific antioxidant and antimicrobial molecules, to fight the pathogen and avoid its spreading into xylem vessels. We provided new information on OQDS resistance mechanism applied by Leccino cultivar. In particular, we evidenced that high concentrations of ROS, switching on plant defence signalling pathways, may represent a key factor in fighting X. fastidiosa infection.


Assuntos
Resistência à Doença , Olea/imunologia , Doenças das Plantas/microbiologia , Xylella , Antioxidantes/metabolismo , Cromatografia Líquida de Alta Pressão , Resistência à Doença/fisiologia , Ensaio de Imunoadsorção Enzimática , Interações Hospedeiro-Patógeno , Microscopia Eletrônica de Varredura , Olea/metabolismo , Olea/microbiologia , Doenças das Plantas/imunologia , Folhas de Planta/metabolismo , Reação em Cadeia da Polimerase , Espécies Reativas de Oxigênio/metabolismo
12.
Genes (Basel) ; 10(4)2019 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-30934761

RESUMO

Among biotic constraints affecting olive trees cultivation worldwide, the soil-borne fungus Verticillium dahliae is considered one of the most serious threats. Olive cultivars display differential susceptibility to the disease, but our knowledge on the pathogen's responses when infecting varieties differing in susceptibility is scarce. A comparative transcriptomic analysis (RNA-seq) was conducted in olive cultivars Picual (susceptible) and Frantoio (tolerant). RNA samples originated from roots during the first two weeks after inoculation with V. dahliae defoliating (D) pathotype. Verticillium dahliae mRNA amount was overwhelmingly higher in roots of the susceptible cultivar, indicating that proliferation of pathogen biomass is favored in 'Picual'. A significant larger number of V. dahliae unigenes (11 fold) were only induced in this cultivar. Seven clusters of differentially expressed genes (DEG) were identified according to time-course expression patterns. Unigenes potentially coding for niche-adaptation, pathogenicity, virulence and microsclerotia development were induced in 'Picual', while in 'Frantoio' expression remained negligible or null. Verticillium dahliae D pathotype transcriptome responses are qualitatively and quantitatively different, and depend on cultivar susceptibility level. The much larger V. dahliae biomass found in 'Picual' roots is a consequence of both host and pathogen DEG explaining, to a large extent, the higher aggressiveness exerted over this cultivar.


Assuntos
Adaptação Fisiológica/genética , Olea/crescimento & desenvolvimento , Transcriptoma/genética , Verticillium/genética , Suscetibilidade a Doenças , Olea/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Análise de Sequência de RNA , Microbiologia do Solo , Verticillium/patogenicidade
13.
Phytochem Anal ; 30(6): 623-634, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31020714

RESUMO

INTRODUCTION: Xylella fastidiosa (Xf) is a pathogenic bacterium that causes diseases in olive trees. Therefore, analytical methods for both the characterisation of the host/pathogen interaction and infection monitoring are needed. Volatile organic compounds (VOCs) are emitted by plants relate to their physiological state, therefore VOCs monitoring can assist in detecting stress or infection states before visible signs are present. OBJECTIVE: In this work, the headspace-solid phase microextraction-gaschromatography-mass spectrometry (HS-SPME-GC-MS) technique was used for the first time to highlight VOCs differences between healthy and Xf-infected olive trees. METHODOLOGY: VOCs from olive tree twig samples were extracted and analysed by HS-SPME-GC-MS, and hence identified by comparing the experimental linear retention indexes with the reference values and by MS data obtained from NIST library. Data were processed by principal component analysis (PCA) and analysis of variance (ANOVA). RESULTS: The HS-SPME step was optimised in terms of adsorbent phase and extraction time. HS-SPME-GC-MS technique was applied to the extraction and analysis of VOCs of healthy and Xf-infected olive trees. More than 100 compounds were identified and the differences between samples were evidenced by the multivariate analysis approach. The results showed the marked presence of methyl esters in Xf-infected samples, suggesting their probable involvement in the mechanism of diffusible signal factor. CONCLUSION: The proposed approach represents an easy and solvent-free method to evaluate the presence of Xf in olive trees, and to evidence volatiles produced by host/pathogen interactions that could be involved in the defensive mechanism of the olive tree and/or in the infective action of Xf.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Olea/química , Olea/microbiologia , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/análise , Xylella/patogenicidade , Análise Multivariada , Olea/classificação
14.
Plant Dis ; 103(4): 656-667, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30823856

RESUMO

Verticillium dahliae is widely distributed in potato and olive fields in Lebanon, causing serious economic losses. However, little is known about the inoculum source, population structure, and genetic diversity of the pathogen or the mechanisms of dissemination within Lebanon. To understand the population structure, a total of 203 isolates sampled from olive (n = 78) and potato (n = 125) were characterized for species, mating type, and race, and the genetic relationships were delineated using 13 microsatellite markers. All isolates except one from potato were V. dahliae, with 55.1 and 12.1% race 1, and 43.6 and 83.1% race 2 in olive and potato, respectively. The genetic structure of the studied population was best described by two large and two small clusters. Membership in the two large clusters was determined by the presence or absence of the effector gene Ave1. Furthermore, genetic structure was moderately associated with the host of origin but was weakly associated with the geographic origin. All but four isolates represented by three multilocus haploid genotypes were MAT1-2. This study identified a clear lack of gene flow between virulence genotypes of V. dahliae despite the proximity of these cropping systems and the wide distribution of genetic diversity among hosts and geographic regions in Lebanon.


Assuntos
Variação Genética , Olea , Solanum tuberosum , Verticillium , DNA Fúngico/genética , Fluxo Gênico , Genótipo , Líbano , Olea/microbiologia , Solanum tuberosum/microbiologia , Verticillium/genética
15.
Environ Sci Pollut Res Int ; 26(7): 6503-6516, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30627995

RESUMO

The meadow froghopper, Philaenus spumarius L., is endemic in Italy and was not considered a harmful species until 2014, when the olive quick decline syndrome (OQDS) showed up in Apulia (southern Italy). It was immediately suspected and then verified as the main vector of Xylella fastidiosa, the bacterium responsible for the disease. Currently, EU Directives consider the fight against P. spumarius compulsory in member states and recommend Integrated Pest Management (IPM), both in uncultivated and cultivated infested areas, to minimise the environmental impact of chemical pesticides. This should be based on an improved knowledge of the vector with its seasonal trends and feeding habits linked to specific herbaceous species. In this context, our field study was aimed to improve the understanding of the vector nutritional behaviour, especially at its critical nymph stage, by monitoring its presence on different herbaceous target species, using its typical feeding foams as key indicator. The study area was in Lazio region (central Italy), dedicated to olive growing and still unaffected by the X. fastidiosa plague. Over two years, during the nymph development period, field data have been acquired over the test area and then analysed by coupling statistical (ANOVA), geographical information system (GIS) and geo-referenced field sampling approaches. Results highlighted that P. spumarius exhibits significant preferences for specific herbaceous plants, especially at its early development stages, detectable by tenuous spittle. This indicates female oviposition activity, which seems also not influenced by olive tree proximity. Furthermore, the non-host plant species identified here could be suitable for creating green barriers for limiting the vector diffusion to contiguous areas where sensible plantations are growing. In the final section, applied implications arising from the present findings for P. spumarius population management are discussed.


Assuntos
Hemípteros/fisiologia , Insetos Vetores , Olea/microbiologia , Xylella/crescimento & desenvolvimento , Animais , Feminino , Hemípteros/microbiologia , Itália , Ninfa , Doenças das Plantas/estatística & dados numéricos
16.
Fungal Biol ; 123(1): 66-76, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30654959

RESUMO

Fungal endophytes are micro-organisms that colonize healthy plant tissues without causing disease symptoms. They are described as plant growth and disease resistance promoters and have shown antimicrobial activity. The spatial-temporal distribution of endophytic communities in olive cultivars has been poorly explored. This study aims to investigate the richness and diversity of endophytic fungi in different seasons and sites, within the Alentejo region, Portugal. Additionally, and because the impact of some pathogenic fungi (e.g. Colletotrichum spp.) varies according to olive cultivars; three cultivars, Galega vulgar, Cobrançosa and Azeiteira, were sampled. 1868 fungal isolates were identified as belonging to 26 OTUs; 13 OTUs were identified to the genera level and 13 to species level. Cultivar Galega vulgar and season autumn showed significant higher values in terms of endophytic richness and diversity. At site level, Elvas showed the lowest fungal richness and diversity of fungal endophytes. This study reinforces the importance of exploring the combined spatio-temporal distribution of the endophytic biodiversity in different olive cultivars. Knowledge about endophytic communities may help to better understand their functions in plants hosts, such as their ecological dynamics with pathogenic fungi, which can be explored for their use as biocontrol agents.


Assuntos
Biodiversidade , Endófitos/isolamento & purificação , Fungos/isolamento & purificação , Olea/microbiologia , Folhas de Planta/microbiologia , Endófitos/classificação , Fungos/classificação , Fungos/genética , Portugal , Estações do Ano , Análise Espaço-Temporal
17.
Food Microbiol ; 78: 179-187, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30497600

RESUMO

Virgin olive oil contains a biotic fraction represented by rich microbiota, including yeasts. The aim of this study was to investigate some physiological properties and the in vitro probiotic potential of yeast strains previously isolated from Italian virgin olive oil. Eleven yeast strains belonging to the species Candida adriatica, Candida diddensiae, Nakazawaea molendini-olei, Nakazawaea wickerhamii, Wickerhamomyces anomalus, and Yamadazyma terventina were used in this study and compared with the reference yeast Saccharomyces boulardii. Present research has demonstrated that unlike Saccharomyces boulardii which produce only satured and monounsatured fatty acids (MUFAs), the olive oil-borne yeast strains also synthesize polyunsatured fatty acids (PUFAs) in quantities greater than those found in olive oil, which provide health benefits. The survival in gastric and pancreatic juices, which is important for probiotic yeasts because it allows them to cross the human intestinal tract, has reached a maximum of 100% when yeast cells were coated with olive oil. Cholesterol was removed by 50% of the studied yeast strains, and among them, the best results were reached by the strains 2032 and 2033 of W. anomalus which appear the best probiotic candidate in terms of the in vitro probiotic trait evaluated. Further experiments are underway to confirm this findings.


Assuntos
Olea/microbiologia , Azeite de Oliva , Probióticos/metabolismo , Saccharomyces cerevisiae/isolamento & purificação , Leveduras/isolamento & purificação , Candida/isolamento & purificação , Candida/metabolismo , Colesterol/metabolismo , Ácidos Graxos Insaturados/biossíntese , Microbiologia de Alimentos , Humanos , Itália , Lipólise , Microbiota , Probióticos/isolamento & purificação , Saccharomyces cerevisiae/fisiologia , Leveduras/fisiologia
18.
Food Chem ; 271: 543-549, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30236714

RESUMO

The effects of the main steps of Spanish-style processing (alkaline treatment and fermentation) on the volatile composition of cv. Manzanilla green olives were studied. Both spontaneous and controlled fermentations were considered. In the latter case, a Lactobacillus pentosus strain from green olive fermentation brine was used as starter culture. The volatile profile was determined by headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). Most of the volatile compounds detected in fresh olives decreased or were undetected after alkaline treatment, while several compounds (mostly acetic acid, 2-methylbutanoic acid, and ethanol) were formed as a result of this treatment. Over 50 new volatile components, mostly esters and phenols, appeared as a result of fermentation. The most outstanding finding was a considerable increase in 4-ethyl phenol (almost 100-fold increase) in inoculated olives compared to the uninoculated product. However, a sensory panel did not find significant differences in odor perception.


Assuntos
Manipulação de Alimentos/métodos , Microbiologia de Alimentos , Lactobacillus pentosus/fisiologia , Óleos Voláteis/análise , Olea/microbiologia , Fermentação , Concentração de Íons de Hidrogênio , Lactobacillus , Olea/química
19.
J Sci Food Agric ; 99(5): 2504-2512, 2019 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-30379330

RESUMO

BACKGROUND: Table olive fermentation is an unpredictable process and frequently performed using traditional practices often inadequate to obtain products with acceptable quality and safety standards. In the present study, the efficacy of selected yeast strains as starters to drive fermentations of green and black table olives by the Greek method was investigated. Pilot-scale production by spontaneous fermentation as a control, olives started with previously selected Saccharomyces cerevisiae strains and fermentation driven by commercial S. cerevisiae baker's yeast strain were carried out for each of Manzanilla, Picual and Kalamàta table olive cultivars. RESULTS: Time of fermentation was significantly shortened to 40 days to complete the transformation process for all three tested cultivars. Inoculated table olives were enhanced in their organoleptic and nutritional properties in comparison with corresponding samples obtained by spontaneous fermentation. The use of starters was also able to improve safety traits of table olives in terms of biogenic amine reduction as well as absence of undesired microorganisms at the end of the process. CONCLUSIONS: Autochthonous, but also non-autochthonous, yeasts can be used to start and control table olive fermentations and can significantly improve quality and safety aspects of table olives produced by many smallholder farmers. © 2018 Society of Chemical Industry.


Assuntos
Olea/microbiologia , Saccharomyces cerevisiae/metabolismo , Fermentação , Microbiologia de Alimentos , Frutas/química , Frutas/microbiologia , Grécia , Olea/química
20.
Math Biosci ; 308: 42-58, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30528333

RESUMO

In this paper we formulate a model for assessing the interaction between the phytopathogen Spilocaea oleaginea and the phyllosphere microorganisms that are present in the olive tree leaves. The model describes the evolution in time of the foliage of the olive tree and the two different microorganisms, the phytopathogen fungi, that negatively affect the plant causing spots in the leaves, and the beneficial phyllosphere microorganisms, that help in keeping in check the invasion of the former. The system possesses five equilibria that are suitably analysed for feasibility and stability. The model shows interesting features: a bistable behavior, exhibited by three different pairs of equilibria. The separatrix surface of the basins of attraction of one such pair is computed. This allows the possible assessment of human intervention for control of the disease. Persistent oscillations via Hopf bifurcation are also discovered.


Assuntos
Ascomicetos , Modelos Biológicos , Micoses/microbiologia , Olea/microbiologia , Doenças das Plantas/microbiologia
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