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1.
PLoS One ; 15(8): e0237466, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790762

RESUMO

In the past decade, two leptospirosis outbreaks occurred among strawberry harvesters in Germany, with 13, and 45 reported cases respectively. In both outbreaks, common voles (Microtus arvalis) infected with Leptospira kischneri serovar Grippotyphosa were identified as the most likely outbreak source. In an univariate analysis, eating unwashed strawberries was identified as one of the risk factors associated with Leptospira infection. The aim of this study was to evaluate the survival time of L. kirschneri serovar Grippotyphosa on strawberries under varying conditions. Strawberries were spiked with 5x109 of both a laboratory reference strain (strain Moskva V) and an outbreak field strain (94-6/2007) of L. kirschneri serovar Grippotyphosa sequence type 110. Survival times were investigated in a fully crossed design with three incubation times (2h, 4h, 6h and 8h) and three temperatures (15°C, 21°C and 25°C) with three replicated for each condition. A wash protocol was developed and recovered Leptospira were determined by qPCR, dark field microscopy and culturing. Viable L. kirschneri of both the reference strain and the field strain were identified in all samples at 25°C and an incubation time of 2h, but only 1/9 (11%) and 4/9 (44%) of the samples incubated at 15°C were positive, respectively. Both reference and field strain were viable only in 2/9 (22%) at 25° after 6h. After an 8h incubation, viable Leptospira could not be identified on the surface of the strawberries or within the fruit for any of the tested conditions. Based on these results, the exposure risk of consumers to viable Leptospira spp. through the consumption of strawberries bought at the retail level is most likely very low. However, there is a potential risk of Leptospira infection by consumption of strawberries on pick-your-own farms.


Assuntos
Fragaria/microbiologia , Leptospira/fisiologia , DNA Bacteriano/metabolismo , Frutas/microbiologia , Alemanha/epidemiologia , Humanos , Leptospira/genética , Leptospirose/epidemiologia , Leptospirose/patologia , Microscopia , Reação em Cadeia da Polimerase em Tempo Real , Sorogrupo , Temperatura , Fatores de Tempo
2.
Mol Genet Genomics ; 295(6): 1415-1429, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32656702

RESUMO

Penicillium expansum is a destructive phytopathogen causing postharvest decay on many stored fruits. To develop effective and safe management strategies, it is important to investigate its pathogenicity-related mechanisms. In this study, a bioinformatic pipeline was constructed and 50 core effector genes were identified in P. expansum using multiple RNA-seq data sets and their putative functions were implicated by comparatively homologous analyses using pathogen-host interaction database. To functionally characterize P. expansum LysM domain proteins during infection, null mutants for the 15 uncharacterized putative LysM effectors were constructed and the fungal growth rate on either PDA or Cazpek medium or lesion expansion rate on the infected apple fruits was evaluated. The results showed the growth rate of knockout mutants from PeLysM5, PeLysM12 and PeLysM15 was retarded on PDA medium. No significant difference in growth rate was observed between wild type and all mutants on solid Cazpek medium. Nevertheless, the hypha of wild type displayed deeper yellow on the back of Cazpek medium than those of knockout mutants. On the infecting apples fruits, the knockout mutants from PeLysM5, PeLysM7, PeLysM8, PeLysM9, PeLysM10, PeLysM11, PeLysM14, PeLysM15, PeLysM16, PeLysM18 and PeLysM19 showed enhanced fungal virulence, with faster decaying on infected fruits than those from wild type. By contrast, the knockout mutation at PeLysM12 locus led to reduced lesion expansion rate on the infected apple fruits. In addition, P. expansum-apple interaction RNA-seq experiment was performed using apple fruit tissues infected by the wild type and knockout mutant ΔPeLysM15, respectively. Transcriptome analyses indicated that deletion of PeLysM15 could activate expression of several core effector genes, such as PEX2_055830, PEX2_036960 and PEX2_108150, and a chitin-binding protein, PEX2_064520. These results suggest PeLysM15 may play pivotal roles in fungal growth and development and involve pathogen-host interaction by modulating other effector genes' expression. Our results could provide solid data reference and good candidates for further pathogen-related studies in P. expansum.


Assuntos
Proteínas Fúngicas/metabolismo , Interações Hospedeiro-Patógeno/genética , Malus/microbiologia , Penicillium/crescimento & desenvolvimento , Penicillium/patogenicidade , Doenças das Plantas/microbiologia , Transcriptoma , Frutas/genética , Frutas/microbiologia , Proteínas Fúngicas/genética , Perfilação da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Malus/genética , Penicillium/genética , Doenças das Plantas/genética , Virulência
3.
PLoS One ; 15(7): e0235345, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32667930

RESUMO

This study was carried out to investigate the risks of simultaneous exposure to pesticide residues and bacteria contaminants in locally produced fresh vegetables and vegetables in Tanzania. A total of 613 samples were analyzed for pesticide residues, out of which 250 were also analyzed for bacterial contamination. Overall, 47.5% had pesticide residues, 74.2% exceeded Maximum Residue Levels (MRLs). Organophosphorus (95.2%), organochlorines (24.0%), pyrethroids (17.3%), and carbamates (9.2%) residues dominated. MRL values were mostly exceeded in tomatoes, onions, watermelons, cucumbers, Chinese cabbage, and sweet paper. Tetramethrin (0.0329-1.3733 mg/kg), pirimiphos-methyl (0.0003-1.4093 mg/kg), permethrin (0.0009-2.4537 mg/kg), endosulfan (beta) (0.0008-2.3416 mg/kg), carbaryl (0.0215-1.5068 mg/kg), profenofos (0.0176-2.1377 mg/kg), chlorpyrifos (0.0004-1.2549 mg/kg) and dieldrin (0.0011-0.5271 mg/kg) exceeded MRLs. The prevalence of bacteria contamination was high (63.2%). Enterobacter (55.6%) Pseudomonas aeruginosa (32.4%), E. coli (28.2%), Citrobacter (26.8%), Klebsiella oxytoca (14.8%), and Salmonella (7.7%) were isolated. Furthermore, 46.4% tested positive for both pesticide residues and bacterial contaminants. Vegetables from farms (60.7%) contained more dual contaminants than market-based vegetables (41.8%). This may have resulted from excessive pesticide use and unhygienic handling of fresh fruits and vegetables at production level. Binary logistic regression showed that fresh fruits and vegetables with pesticide residues were 2.231 times more likely to have bacteria contaminants (OR: 2.231; 95% CI: 0.501, 8.802). The contamination levels of pesticide residues and bacterial contaminants could be perceived as a serious problem as most fresh fruits and vegetables recorded values of pesticide residues far above the MRLs with pathogenic bacteria isolated in higher proportions. MRLs was higher in most vegetables consumed raw or semi-cooked such as watermelons, carrots, cucumber, tomatoes, onion and sweet paper. There is an urgent need to develop pesticide monitoring and surveillance systems at farmer level, educating farmers and promoting the use of greener pesticides to mitigate the health effects of pesticides and bacterial contaminants.


Assuntos
Contaminação de Alimentos/análise , Frutas/efeitos adversos , Praguicidas/efeitos adversos , Verduras/efeitos adversos , Citrobacter/isolamento & purificação , Citrobacter/patogenicidade , Enterobacter/isolamento & purificação , Enterobacter/patogenicidade , Frutas/química , Frutas/microbiologia , Humanos , Hidrocarbonetos Clorados/efeitos adversos , Hidrocarbonetos Clorados/química , Klebsiella oxytoca/isolamento & purificação , Klebsiella oxytoca/patogenicidade , Resíduos de Praguicidas/efeitos adversos , Resíduos de Praguicidas/química , Praguicidas/química , Pseudomonas aeruginosa/isolamento & purificação , Pseudomonas aeruginosa/patogenicidade , Piretrinas/efeitos adversos , Piretrinas/química , Salmonella/isolamento & purificação , Salmonella/patogenicidade , Verduras/química , Verduras/microbiologia
4.
Int J Syst Evol Microbiol ; 70(7): 4351-4357, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32584749

RESUMO

Two bacterial strains, isolates AC10T and AC20, which were reported in a previous study on the diversity of acetic acid bacteria in Thailand, were subjected to a taxonomic study. The phylogenetic analysis based on the 16S rRNA gene sequences showed that the two isolates were located closely to the type strains of Gluconobacter oxydans and Gluconobacter roseus. However, the two isolates formed a separate cluster from the type strains of the two species. The genomic DNA of isolate AC10T was sequenced. The assembled genomes of the isolate were analysed for average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH). The results showed that the highest ANI and dDDH values between isolate AC10T and G. oxydans DSM 3503T were 91.15 and 68.2 %, which are lower than the suggested values for species delineation. The genome-based tree was reconstructed and the phylogenetic lineage based on genome sequences showed that the lineage of isolate AC10T was distinct from G. oxydans DSM 3503T and its related species. The two isolates were distinguished from G. oxydans and their relatives by their phenotypic characteristics and MALDI-TOF profiles. Therefore, the two isolates, AC10T (=BCC 15749T=TBRC 11329T=NBRC 103576T) and AC20 (=BCC 15759=TBRC 11330=NBRC 103579), can be assigned to an independent species within the genus Gluconobacter, and the name Gluconobacter aidae sp. nov. is proposed for the two isolates.


Assuntos
Frutas/microbiologia , Gluconobacter/classificação , Filogenia , Ácido Acético , Ananas/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , Citrullus/microbiologia , DNA Bacteriano/genética , Gluconobacter/isolamento & purificação , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Tailândia
5.
Int J Food Microbiol ; 330: 108713, 2020 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-32512363

RESUMO

Sodium metabisulfite (SMBS), potassium metabisulfite (PMBS), aluminum sulfate (AlS) and aluminum potassium sulfate (AlPS), common sulfur-containing salts used as food additives, were evaluated for their antifungal activity against Penicillium digitatum, Penicillium italicum and Geotrichum citri-aurantii, the most economically important pathogens causing postharvest diseases of citrus fruits. In vitro radial mycelial growth was measured on potato dextrose agar (PDA) Petri dishes amended with five different concentrations of the salts (10, 20, 30, 50, 100 mM) after 7 d of incubation at 25 °C. SMBS and PMBS at all concentrations, and AIS and AIPS above 20 mM, completely inhibited the growth of these fungi. The curative antifungal activity of the four salts to control citrus green (GM) and blue (BM) molds and sour rot (SR) was evaluated on 'Valencia' oranges artificially inoculated in rind wounds with P. digitatum, P. italicum and G. citri-aurantii, respectively. In vivo primary screenings showed no significant antifungal activity of AlS and AlPS to control the three diseases at any dose tested, but SMBS and PMBS reduced the incidence and severity of GM, BM and SR at various concentrations. Effective salts and concentrations were selected for in vivo dip treatments in small-scale trials. Dips at room temperature (20 °C) in SMBS and PMBS at 20 and 50 mM for 60 or 120 s significantly reduced the incidence and severity of GM and BM, with PMBS at 50 mM for 120 s the most effective treatment. Conversely, dips in SMBS and PMBS at 50 mM for 60 or 120 s did not reduce SR incidence and severity. SMBS and PMBS treatments are potentially new tools to be included in reduced-risk non-polluting strategies to control Penicillium diseases, but not SR, on citrus fruits.


Assuntos
Antifúngicos/farmacologia , Citrus/microbiologia , Aditivos Alimentares/farmacologia , Doenças das Plantas/prevenção & controle , Enxofre/farmacologia , Aditivos Alimentares/química , Conservação de Alimentos/métodos , Frutas/microbiologia , Fungos/efeitos dos fármacos , Fungos/crescimento & desenvolvimento , Doenças das Plantas/microbiologia , Temperatura , Fatores de Tempo
6.
Int J Food Microbiol ; 331: 108694, 2020 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-32521373

RESUMO

This study evaluated if coatings with chitosan (Chi) and phenolic-rich extract from acerola (Malpighia emarginata D.C., PEA) or jabuticaba (Plinia jaboticaba (Vell.) Berg, PEJ) processing by-products are effective to control the development of rot caused by Lasiodiplodia pseudotheobromae, L. viticola, L. euphorbicola, L. theobromae and L. hormozganensis in papaya (Carica papaya L.) fruit. Effects of formulated coatings on some physicochemical parameters indicative of postharvest quality of papaya were investigated. Twenty-six different phenolics were found in PEA and PEJ, including flavonoids, stilbenes, tannins and phenolic acids. Chi (1-5 mg/mL), PEA and PEJ (25-100 mg/mL) separately caused mycelial growth inhibition on all isolates. Combinations of Chi (3 and 4 mg/mL) and PEA (50 and 75 mg/mL) or PEJ (75 and 100 mg/mL) had additive interactions. Coatings with Chi (4 mg/mL) and PEA (50 or 75 mg/mL) or PEA (75 or 100 mg/mL) inhibited rot development in papaya fruit infected with Lasiodiplodia isolates during 8 days of room temperature storage. Coatings with 4 mg/mL Chi and 75 mg/mL PEA or 100 mg/mL PEJ were the most effective to control rot development. These coatings did not affect negatively physicochemical parameters indicative of postharvest quality of papaya fruit during storage. Coatings with combined Chi and PEA or PEJ could be novel strategies to control postharvest rot caused by Lasiodiplodia in papaya fruit.


Assuntos
Carica/microbiologia , Manipulação de Alimentos/métodos , Microbiologia de Alimentos , Frutas/microbiologia , Malpighiaceae/química , Myrtaceae/química , Extratos Vegetais/farmacologia , Ascomicetos/efeitos dos fármacos , Quitosana/farmacologia , Fenóis/farmacologia
7.
Arch Microbiol ; 202(9): 2391-2400, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32588084

RESUMO

An amplicon metagenomic approach based on the ITS1 region of fungal rDNA was employed to identify the composition of fungal communities associated with diseases of pear fruits during postharvest storage. The sampled fruits were harvested at an orchard using routine management practices involving treatments with various chemical fungicides and were transferred to a storage packinghouse. Effective tags of reading sequences clustered into 53 OTUs whereas Ascomycota was the dominant phylum (83.4%) followed by Basidiomycota (15.8%). Our results revealed that four genera, Penicillium, Rhodotorula, Alternaria and Cladosporium were the most abundant representing 59-95% of the relative abundance per sample. The interruption of chemical treatments during the last month before harvest altered the structure of the fungal community of fruits among untreated and treated samples, mainly in cases of relative abundance of Penicillium and Rhodotorula genera. We hypothesize that various antagonistic interactions might occur on fruit surfaces among the detected fungal genera whose relative abundances were affected by fungicide treatments. Interestingly, some common pre- and postharvest pear fungal pathogens were either less present (such as Moniliana), or undetected (such as Aspergillus, Venturia and Septoria) in untreated and treated samples.


Assuntos
Microbiologia de Alimentos , Frutas/microbiologia , Fungos , Metagenômica , Micobioma , Pyrus/microbiologia , Fungos/classificação , Fungos/efeitos dos fármacos , Fungos/genética , Fungicidas Industriais/farmacologia , Micobioma/efeitos dos fármacos , Micobioma/genética
8.
PLoS One ; 15(5): e0233916, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32470037

RESUMO

The olive tree (Olea europaea L.) is the most important oil-producing crop of the Mediterranean basin. However, although plant protection measures are regularly applied, disease outbreaks represent an obstacle towards the further development of the sector. Therefore, there is an urge for the improvement of plant protection strategies based on information acquired by the implementation of advanced methodologies. Recently, heavy fungal infections of olive fruits have been recorded in major olive-producing areas of Greece causing devastating yield losses. Thus, initially, we have undertaken the task to identify their causal agent(s) and assess their pathogenicity and sensitivity to fungicides. The disease was identified as the olive anthracnose, and although Colletotrichum gloeosporioides and Colletotrichum acutatum species complexes are the two major causes, the obtained results confirmed that in Southern Greece the latter is the main causal agent. The obtained isolates were grouped into eight morphotypes based on their phenotypes, which differ in their sensitivities to fungicides and pathogenicity. The triazoles difenoconazole and tebuconazole were more toxic than the strobilurins being tested. Furthermore, a GC/EI/MS metabolomics model was developed for the robust chemotaxonomy of the isolates and the dissection of differences between their endo-metabolomes, which could explain the obtained phenotypes. The corresponding metabolites-biomarkers for the discrimination between morphotypes were discovered, with the most important ones being the amino acids L-tyrosine, L-phenylalanine, and L-proline, the disaccharide α,α-trehalose, and the phytotoxic pathogenesis-related metabolite hydroxyphenylacetate. These metabolites play important roles in fungal metabolism, pathogenesis, and stress responses. The study adds critical information that could be further exploited to combat olive anthracnose through its monitoring and the design of improved, customized plant protection strategies. Also, results suggest the necessity for the comprehensive mapping of the C. acutatum species complex morphotypes in order to avoid issues such as the development of fungicide-resistant genotypes.


Assuntos
Colletotrichum/fisiologia , Olea/microbiologia , Doenças das Plantas/prevenção & controle , Colletotrichum/efeitos dos fármacos , Colletotrichum/crescimento & desenvolvimento , Colletotrichum/isolamento & purificação , Flores/microbiologia , Frutas/microbiologia , Fungicidas Industriais/farmacologia , Grécia , Metabolômica , Azeite de Oliva , Folhas de Planta/microbiologia , Especificidade da Espécie , Virulência/efeitos dos fármacos
9.
PLoS One ; 15(5): e0232626, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32374762

RESUMO

The aim of this study is to determine the involvement of the flavonol-anthocyanin pathway on plant adaptation to biotic stress using the B.amyloliquefaciens QV15 to trigger blackberry metabolism and identify target genes to improve plant fitness and fruit quality. To achieve this goal, field-grown blackberries were root-inoculated with QV15 along its growth cycle. At fruiting, a transcriptomic analysis by RNA-Seq was performed on leaves and fruits of treated and non-treated field-grown blackberries after a sustained mildew outbreak; expression of the regulating and core genes of the Flavonol-Anthocyanin pathway were analysed by qPCR and metabolomic profiles by UHPLC/ESI-qTOF-MS; plant protection was found to be up to 88%. Overexpression of step-controlling genes in leaves and fruits, associated to lower concentration of flavonols and anthocyanins in QV15-treated plants, together with a higher protection suggest a phytoanticipin role for flavonols in blackberry; kempferol-3-O-rutinoside concentration was strikingly high. Overexpression of RuF3H (Flavonol-3-hidroxylase) suggests a pivotal role in the coordination of committing steps in this pathway, controlling carbon flux towards the different sinks. Furthermore, this C demand is supported by an activation of the photosynthetic machinery, and boosted by a coordinated control of ROS into a sub-lethal range, and associated to enhanced protection to biotic stress.


Assuntos
Adaptação Fisiológica , Antocianinas/metabolismo , Bacillus amyloliquefaciens/fisiologia , Sistema Enzimático do Citocromo P-450/fisiologia , Rubus/enzimologia , Rubus/microbiologia , Estresse Fisiológico , Sistema Enzimático do Citocromo P-450/genética , Frutas/enzimologia , Frutas/genética , Frutas/microbiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas/genética , Folhas de Planta/enzimologia , Folhas de Planta/microbiologia , Rubus/genética
10.
Int J Syst Evol Microbiol ; 70(5): 3278-3286, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375936

RESUMO

A novel bacterial strain, designated TOUT106T, was isolated from the surface of a tomato. The cells were rod-shaped, Gram-negative, encapsulated and non-motile. Strain TOUT106T grows best at 28 °C and pH 7.0 and can tolerate up to 2 % (w/v) NaCl. Based on 16S rRNA gene phylogeny, strain TOUT106T was placed close to the Salmonella clade, with close similarity to Salmonella enterica subsp. arizonae strain NCTC 8297T (98.42 %). Results of genome-based phylogenetic analysis revealed that strain TOUT106T is placed well in the Klebsiella-Raoultella clade, by forming a distinct branch with Klebsiella michiganensis DSM25444T, Klebsiella oxytoca NCTC132727T, Klebsiella grimontii 06D021T and Klebsiella pasteurii SB6412T. The genomic DNA G+C content of strain TOUT106T is 53.53 mol%. The average nucleotide identity values of TOUT106T were less than 86.5 % with closely related members of the family Enterobacteriaceae. The major fatty acids of strain TOUT106T were C16 : 0, C17:0 cyclo, C14:0 3OH/C16:1 iso, C14 : 0, C19:0 cyclo ω8c, C18:1 ω6c/C18:1 ω7c, C12 : 0 and C16:1 ω7c/C16:1 ω6c. Strain TOUT106T showed differences in physiological, phenotypic and protein profiles by MALDI-TOF MS compared to its closest relatives. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain TOUT106T could be distinguished from the recognized species of the genus Klebsiella. It is suggested to represent a novel species of this genus, for which the name Klebsiella indica sp. nov. is proposed. The type strain is TOUT106T (=MCC 2901T=KACC 21384T=JCM 33718T).


Assuntos
Frutas/microbiologia , Klebsiella/classificação , Lycopersicon esculentum/microbiologia , Filogenia , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Índia , Klebsiella/isolamento & purificação , Hibridização de Ácido Nucleico , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
11.
Int J Food Microbiol ; 326: 108649, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32402917

RESUMO

In this study we assessed the efficacy of chitosan (CHI) (2%) emulsion added with Ruta graveolens L. essential oil (REO) at different concentrations (0.5%, 1.0% and 1.5%) to control C. gloesporioides grows both "in situ" and "in vitro" in papaya Maradol (Carica papaya L.). In vitro studies showed a decrease on fungal growth (mycelia diameter) with the increase of REO concentration, while 0.5% of REO induce a reduction of 56.42%, REO at 1.0% and 1.5% induced a reduction of 97%. Microscopic analysis showed irreversible deleterious morphological and ultrastructural alterations as well as changes in conidia morphology, and conidia germination inhibition up to 90%. Among the most abundant REO constituents, 2-Nonanol showed strong antifungal activity followed by 2-Undecanone, Benzyl acetate, 2-Nonanone, 2-Tridecanone and 2-Dodecanone. Studies "in situ" on papaya fruit during 12 days at 20 °C, showed a reduction of the C. gloesporioides lesion expansion by 50% using CHI-REO 0.5% emulsions and by 100% with treatments of CHI-REO 1.0 and 1.5%, in addition the emulsions were efficacious to reduce the fruit surface microbiota. On the other hand, physicochemical analysis of the papaya fruits demonstrated that CHI-REO emulsions treatment delayed papaya ripening without affecting the organoleptic characteristics. All these results demonstrated for the first time the application of coatings CHI-REO as a postharvest treatment for the control of anthracnose on papaya fruit.


Assuntos
Antifúngicos/farmacologia , Carica/microbiologia , Quitosana/farmacologia , Colletotrichum/efeitos dos fármacos , Óleos Voláteis/farmacologia , Ruta/metabolismo , Emulsões , Frutas/microbiologia , Micélio/crescimento & desenvolvimento , Esporos Fúngicos/crescimento & desenvolvimento
12.
Int J Syst Evol Microbiol ; 70(3): 1585-1590, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32228772

RESUMO

A novel lactic acid bacterium, strain MB7T, was isolated from lychee in Taiwan. MB7T is Gram-staining-positive, catalase-negative, non-motile, non-haemolytic, facultatively anaerobic, coccoid-shaped, heterofermentative and mainly produces d-lactic acid from glucose. Comparative analysis of 16S rRNA, pheS and rpoA gene sequences has demonstrated that the novel strain represented a member of the genus Leuconostoc. 16S rRNA gene sequencing results indicated that MB7T had the same sequence similarity of 99.25 % to four type strains of members of the genus Leuconostoc: Leuconostoc mesenteroides subsp. dextranicum DSM 20484T, Leuconostoc mesenteroides subsp. jonggajibkimchii DRC 1506T, Leuconostoc mesenteroides subsp. mesenteroides ATCC 8293T and Leuconostoc suionicum DSM 20241T. Additionally, high 16S rRNA sequence similarities were also observed with Leuconostoc mesenteroides subsp. cremoris ATCC 19254T (99.12 %) and Leuconostoc pseudomesenteroides NRIC 1777T (98.69 %). When comparing the genomes of these type strains, the average nucleotide identity values and digital DNA-DNA hybridization values of MB7T with these type strains were 76.57-80.53 and 22.0-22.6 %, respectively. MB7T also showed different phenotypic characteristics to other most closely related species of the genus Leuconostoc, such as carbohydrate metabolizing ability, halotolerance and growth at various pHs. On the basis of phenotypic and genotypic properties, strain MB7T represents a novel species belonging to the genus Leuconostoc, for which the name Leuconostoc litchii sp. nov. is proposed. The type strain is MB7T (=BCRC 81077T=NBRC 113542T).


Assuntos
Frutas/microbiologia , Leuconostoc/classificação , Litchi/microbiologia , Filogenia , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Fermentação , Ácido Láctico , Leuconostoc/isolamento & purificação , Leuconostoc mesenteroides , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Taiwan
13.
Food Chem ; 324: 126891, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32339790

RESUMO

We determined whether heat and chemical treatments could reduce the decay of kiwifruit caused by Botrytis cinerea during postharvest storage. Kiwifruits were treated with 5 g/L (w/v) potassium sorbate (PS), with a 48 °C hot water treatment (HT), and with a combined treatment (HT + PS). Mycelial growth of B. cinerea and the postharvest quality of 'XuXiang' kiwifruits were evaluated. HT + PS significantly inhibited mycelial growth, germ tube growth, and spore germination of B. cinerea. This treatment also reduced the incidence of gray mold in kiwifruit postharvest, and enhanced activities of defense-related enzymes in kiwifruit tissues. Compared with the control, all treatments resulted in lower malondialdehyde (MDA) contents and higher total phenolic contents in kiwifruits. HT + PS also increased the activities of chitinase and ß-1,3-glucanase and the transcript levels of their encoding genes. HT + PS can improve kiwifruit quality and reduce decay during postharvest storage.


Assuntos
Actinidia/microbiologia , Botrytis/efeitos dos fármacos , Ácido Sórbico/farmacologia , Actinidia/química , Actinidia/enzimologia , Botrytis/genética , Quitinases/genética , Quitinases/metabolismo , DNA Fúngico/metabolismo , Qualidade dos Alimentos , Frutas/química , Frutas/enzimologia , Frutas/microbiologia , Glucana 1,3-beta-Glucosidase/genética , Glucana 1,3-beta-Glucosidase/metabolismo , Temperatura Alta , Malondialdeído/metabolismo , Fenóis/metabolismo
14.
Food Chem ; 321: 126704, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32234637

RESUMO

This research measured the optical absorption (µa) and reduced scattering (µs') properties in peaches during quality deterioration, and determine the relationships of the optical parameters with select structural and biochemical parameters. Spatially resolved reflectance was measured for healthy and fungal infected peaches, followed by physical (the size and tissue color), structural [membrane permeability and SEM], and biochemical (Vc, soluble sugar, titratable acid, chlorophyll, total phenolic content) measurements. Both µa and µs' were correlated well with the cellulosic structural and biochemical parameters of peaches, and they had the best correlations with those quality parameters at 675 nm. The correlation of µs' with membrane permeability was the highest from -0.962-0.743, while µa had the best correlation with the chlorophyll content at 675 nm which is an indicator of plant maturation and senescence. These findings would be useful for further development of an effective optical technique for early disease detection of peach fruit.


Assuntos
Prunus persica/microbiologia , Clorofila/análise , Clorofila/biossíntese , Frutas/metabolismo , Frutas/microbiologia , Prunus persica/metabolismo
15.
Food Chem ; 321: 126701, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32283502

RESUMO

The antifungal activity of a library of twenty-four aromatic methoximes was examined against five representative postharvest phytopathogenic fungi. The panel included Penicillium digitatum, Penicillium italicum, Rhizopus stolonifer, Botrytis cinerea and Monilinia fructicola, all of which cause relevant economic losses worldwide as a result of affecting harvested fruits. The minimum inhibitory concentrations and minimum fungicidal concentrations of each compound were defined and the main structure-activity relationships were determined. Although other congeners were more potent, drug likeliness considerations pointed to the methoxime derived from 2,4-dihydroxypropiophenone as the compound with the most suitable profile. The morphology of the colonies of the fungal strains treated with the methoxime was examined microscopically and the compound was also tested in freshly harvested peaches and oranges, exhibiting promising control profiles in both fruits, similar to those of the commercial agents Imazalil and Carbendazim.


Assuntos
Antifúngicos/química , Antifúngicos/farmacologia , Frutas/microbiologia , Oximas/química , Ascomicetos/efeitos dos fármacos , Botrytis/efeitos dos fármacos , Citrus sinensis/efeitos dos fármacos , Citrus sinensis/microbiologia , Frutas/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Oximas/farmacologia , Penicillium/efeitos dos fármacos , Prunus persica/efeitos dos fármacos , Prunus persica/microbiologia , Rhizopus/efeitos dos fármacos , Relação Estrutura-Atividade
16.
Int J Food Microbiol ; 325: 108629, 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32325344

RESUMO

High pressure processing is a mild preservation process that inactivates pathogenic and spoilage micro-organisms in food products, but preserves the fresh characteristics of a product. Compared to untreated product, an enhanced shelf life is obtained during refrigerated storage. Knowledge on the use of high pressure pasteurisation aimed for ambient storage is limited. The aim of this research was to investigate if a combination of high pressure and moderate heat could be used to produce a shelf-stable high-acid fruit product. Ascospores of the heat resistant fungi Talaromyces macrosporus and Aspergillus fischeri were added to fresh strawberry puree that served as a model system. The effect of the processing steps and storage at ambient temperature for 2 weeks was studied on viability of the ascospores. A preheating step at 69 °C/2 min resulted in full or partial activation of A. fischeri and T. macrosporus spores, respectively. The pressure build-up by the process without any holding time resulted in additional activation of spores. A combination of moderate heat (maximum 85-90 °C) and high pressure (500-700 MPa) for holding times up to 13 min inactivated these highly resistant spores much faster than a heat treatment alone. At Tmax = 85 °C and 600 MPa the spores of T. macrosporus and A. fischeri were inactivated by 5.0 and 5.5 log10 after 13 and 7 min, respectively. At Tmax = 85 °C the heat treatment alone did not reduce the viability of these spores up to 60 min of treatment. At Tmax = 90 °C the holding time of the combined pressure-heat treatment could be reduced to obtain the same degree of inactivation of the heat resistant fungi. In addition, treated and untreated ascospores in strawberry puree were stored for 14 days at room temperature to evaluate delayed outgrowth of spores. Untreated ascospores of A. fischeri were activated by storage in the puree. However, at conditions combining high pressure ≥ 600 MPa with Tmax ≥ 85 °C for 13 min, heat resistant fungi were successfully inactivated. This research showed that a combination of moderate heat and pressure can drastically improve the effectiveness to inactivate heat-resistant ascospores in a high-acid fruit product compared to a heat treatment, potentially resulting in a better product quality.


Assuntos
Aspergillus/crescimento & desenvolvimento , Pasteurização/métodos , Esporos Bacterianos/crescimento & desenvolvimento , Esporos Fúngicos/crescimento & desenvolvimento , Talaromyces/crescimento & desenvolvimento , Microbiologia de Alimentos , Fragaria/microbiologia , Frutas/microbiologia , Temperatura Alta
17.
Int J Food Microbiol ; 322: 108585, 2020 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-32179333

RESUMO

A total of 20 dried date samples, chosen as representative among those available on the Perugia (Umbria, Central Italy) market, were analyzed for the possible occurrence of fungal species and related contamination by fungal secondary metabolites. Twenty-six isolates, representative of the total mycobiota, were obtained and morphologically identified as belonging to the genera Aspergillus, Penicillium and Cladosporium. Inside each genus, molecular characterization (by partial sequencing of ITS region and/or ß-tubulin and calmodulin regions for Aspergillus and Penicillium isolates or actin region for Cladosporium isolates) and in vitro mycotoxigenic profile characterization (by LC-MS/MS analysis) showed the presence of the following species: A. flavus, A. tubingensis, P. brevicompactum, P. chrysogenum, P. crustosum, P. glabrum, P. solitum, P. venetum, C. cladosporioides, C. limoniforme and C. halotolerans, with A. tubingensis as the prevalent species and P. crustosum, P. solitum, P. venetum and C. limoniforme first reported here on dates. Date packaging and format showed an effect on the incidence of isolated fungi, with the lowest incidence recovered from whole dates and in hermetic bag packaging. These findings can be useful both for dried dates producers and consumers, guiding them towards choices of packaging and format with a lower risk of mycotoxigenic species presence. However, no fungal metabolites were detected in the dried date samples analyzed, which were therefore regarded as safe for human consumption, underlining the absence of correspondence between fungal isolation and mycotoxin contaminations.


Assuntos
Microbiologia de Alimentos , Alimentos em Conserva/microbiologia , Fungos/isolamento & purificação , Phoeniceae/microbiologia , Aspergillus/classificação , Aspergillus/genética , Aspergillus/isolamento & purificação , Aspergillus/metabolismo , Cladosporium/classificação , Cladosporium/genética , Cladosporium/isolamento & purificação , Cladosporium/metabolismo , Embalagem de Alimentos/métodos , Frutas/microbiologia , Fungos/classificação , Fungos/genética , Fungos/metabolismo , Humanos , Itália , Micotoxinas/análise , Penicillium/classificação , Penicillium/genética , Penicillium/isolamento & purificação , Penicillium/metabolismo
18.
PLoS One ; 15(3): e0226448, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32214345

RESUMO

Rapid Alkalinization Factors (RALFs) are cysteine-rich peptides ubiquitous within plant kingdom. They play multiple roles as hormonal signals in diverse processes, including root elongation, cell growth, pollen tube development, and fertilization. Their involvement in host-pathogen crosstalk as negative regulators of immunity in Arabidopsis has also been recognized. In addition, peptides homologous to RALF are secreted by different fungal pathogens as effectors during early stages of infection. Previous studies have identified nine RALF genes in the diploid strawberry (Fragaria vesca) genome. This work describes the genomic organization of the RALF gene families in commercial octoploid strawberry (Fragaria × ananassa) and the re-annotated genome of F. vesca, and then compares findings with orthologs in Arabidopsis thaliana. We reveal the presence of 15 RALF genes in F. vesca genotype Hawaii 4 and 50 in Fragaria x ananassa cv. Camarosa, showing a non-homogenous localization of genes among the different Fragaria x ananassa subgenomes. Expression analysis of Fragaria x ananassa RALF genes upon infection with Colletotrichum acutatum or Botrytis cinerea showed that FanRALF3-1 was the only fruit RALF gene upregulated after fungal infection. In silico analysis was used to identify distinct pathogen inducible elements upstream of the FanRALF3-1 gene. Agroinfiltration of strawberry fruit with deletion constructs of the FanRALF3-1 promoter identified a 5' region required for FanRALF3-1 expression in fruit, but failed to identify a region responsible for fungal induced expression.


Assuntos
Botrytis , Colletotrichum , Cruzamentos Genéticos , Fragaria , Frutas , Família Multigênica , Proteínas de Neoplasias , Doenças das Plantas , Proteínas de Plantas , Fragaria/genética , Fragaria/microbiologia , Frutas/genética , Frutas/microbiologia , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
19.
Mol Plant Microbe Interact ; 33(6): 790-793, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32163336

RESUMO

Colletotrichum fructicola is a plant-pathogenic fungus with a broad host range. It causes significant losses to important crops, including apple, pear, strawberry, and other Rosaceae and non-Rosaceae species. To date, two short read-based C. fructicola genomes are publicly available, but both are fragmented. In this study, we re-sequenced the genome of C. fructicola using nanopore long-read technology and refined the assembly with Hi-C map data. The resulting high-quality assembly is an important resource for further comparative and experimental studies with C. fructicola.


Assuntos
Colletotrichum/genética , Genoma Fúngico , Doenças das Plantas/microbiologia , Rosaceae/microbiologia , Produtos Agrícolas/microbiologia , Frutas/microbiologia , Sequenciamento por Nanoporos , Filogenia
20.
PLoS One ; 15(3): e0230269, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32176885

RESUMO

Secondary peat swamp forest (PSF) arise by degradation of primary PSF as a result of fire and human activities. Yeasts diversity of Kuan Kreng (KK) and Rayong Botanical Garden (RBG) PSF, which are two secondary PSF in southern and in eastern Thailand, respectively, were investigated. Yeasts were isolated from soil and peat soil by the dilution plate and enrichment techniques. From six samples collected from KK PSF, 35 strains were obtained, and they were identified based on the sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene 13 species in 12 genera, and one potential new species of the genus Galactomyces were detected. Thirty-two strains were obtained from six samples collected from RBG PSF and 26 strains were identified as 13 known yeast species in 11 genera, whereas six strains were found to represent two potential new species of the genera Papiliotrema and Moesziomyces. Among yeast strains isolated from KK PSF, the number of strains in the phylum Ascomycota and Basidiomycota were equal, whereas there were slightly fewer strains in Ascomycota than in Basidiomycota among the strains obtained from RBG PSF. The yeast strains were evaluated for their antagonistic activities against fungal pathogens which cause rice diseases (Fusarium moniliforme, Helminthosporium oryzae, Rhizoctonia solani, Curvularia lunata and Pyricularia grisea) and postharvest disease of fruits (Phytophthora palmivora, Lasiodiplodia theobromae and Colletotrichum gloeosporioides). Twelve strains of seven species were found to be antagonistic yeast strains. Starmerella kuoi DMKU-SPS13-6, Hanseniaspora lindneri DMKU ESS10-9 and Piskurozyma taiwanensis DMKU-SPS12-2 capable to inhibit R. solani by 70.1-76.2%, Wickerhamomyces anomalus DMKU SPS6-1 and three Rhodotorula taiwanensis strains (DMKU SPS8-1, DMKU ESS9-3, DMKU SPS9-2) inhibited C. lunata by 69.8-71.9%, Hanseniaspora lindneri DMKU ESS10-9 and Scheffersomyces spartinae DMKU SPS9-3 inhibited P. grisea by 81.9-84.4% and four Papiliotrema laurentii strains (DMKU-SPS15-1, DMKU-ESS11-2, DMKU-ESS8-2, DMKU-ESS6-4) inhibited P. palmivora by 53.2-59.5%.


Assuntos
Florestas , Frutas/microbiologia , Doenças das Plantas/microbiologia , Solo , Áreas Alagadas , Leveduras/fisiologia , Geografia , Filogenia , Microbiologia do Solo , Tailândia , Leveduras/classificação , Leveduras/genética , Leveduras/crescimento & desenvolvimento
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