RESUMO
BACKGROUND: The native potatoes (Solanum tuberosum subsp. tuberosum L.) grown in Chile (Chiloé) represent a new, unexplored source of endophytes to find potential biological control agents for the prevention of bacterial diseases, like blackleg and soft rot, in potato crops. RESULT: The objective of this study was the selection of endophytic actinobacteria from native potatoes for antagonistic activity against Pectobacterium carotovorum subsp. carotovorum and Pectobacterium atrosepticum, and their potential to suppress tissue maceration symptoms in potato tubers. This potential was determined through the quorum quenching activity using a Chromobacterium violaceaum ATCC 12472 Wild type (WT) bioassay and its colonization behavior of the potato plant root system (S. tuberosum) by means of the Double labeling of oligonucleotide probes for fluorescence in situ hybridization (DOPE-FISH) targeting technique. The results showed that although Streptomyces sp. TP199 and Streptomyces sp. A2R31 were able to inhibit the growth of the pathogens, only the Streptomyces sp. TP199 isolate inhibited Pectobacterium sp. growth and diminished tissue maceration in tubers (p ≤ 0.05). Streptomyces sp. TP199 had metal-dependent acyl homoserine lactones (AHL) quorum quenching activity in vitro and was able to colonize the root endosphere 10 days after inoculation. CONCLUSIONS: We concluded that native potatoes from southern Chile possess endophyte actinobacteria that are potential agents for the disease management of soft rot and blackleg.
Assuntos
Actinobacteria/fisiologia , Antibiose/fisiologia , Endófitos/fisiologia , Solanum tuberosum/microbiologia , Actinobacteria/classificação , Actinobacteria/genética , Actinobacteria/isolamento & purificação , Agentes de Controle Biológico/isolamento & purificação , Chile , Endófitos/classificação , Endófitos/genética , Endófitos/isolamento & purificação , Pectobacterium/fisiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Tubérculos/microbiologia , Percepção de Quorum , Streptomyces/classificação , Streptomyces/genética , Streptomyces/isolamento & purificação , Streptomyces/fisiologiaRESUMO
Even today, weeds continue to be a considerable problem for agriculture. The application of synthetic herbicides produces serious environmental consequences, and crops suffer loss of their activity due to the appearance of new resistant weed biotypes. Our aim is to develop new effective natural herbicides that improve the problem of resistance and do not harm the environment. This work is focused on a bioassay-guided isolation and the characterization of natural products present in Moquiniastrum pulchrum leaves with phytotoxic activity and its preliminary application in weeds. Moquiniastrum pulchrum was selected for two reasons: it is an abundant species in the Cerrado region (the second most important ecosystem in Brazil, after the Amazon)-the explanation behind its being a dominant species is a major focus of interest-and it has traditional employment in folk medicine. Six major compounds were isolated in this plant: one flavone and five diterpenes, two of which are described for the first time in the literature. Four of the six compounds exhibited phytotoxic activity in the bioassays performed. The results confirmed the phytotoxic potential of this plant, which had not been investigated until now.
Assuntos
Asteraceae/química , Agentes de Controle Biológico/toxicidade , Diterpenos/toxicidade , Flavonas/toxicidade , Herbicidas/toxicidade , Plantas Daninhas/efeitos dos fármacos , Controle de Plantas Daninhas/métodos , Bioensaio , Agentes de Controle Biológico/química , Agentes de Controle Biológico/isolamento & purificação , Produtos Agrícolas/crescimento & desenvolvimento , Diterpenos/química , Diterpenos/isolamento & purificação , Flavonas/química , Flavonas/isolamento & purificação , Herbicidas/química , Herbicidas/isolamento & purificação , Humanos , Estrutura Molecular , Extratos Vegetais/química , Folhas de Planta/química , Plantas Daninhas/crescimento & desenvolvimentoRESUMO
The objectives of the present study were to purify and assess the killer toxin effect produced by Aureobasidium pullulans under casual agents of green mold (Penicillum digitatum) and sour rot (Geotrichum citri-aurantii). Initially, different methods of protein precipitation were tested. The proteolytic activity and the presence of proteins acting on cell wall receptors, ß-1,3-glucanase and chitinase were determined, and toxin purification was conducted by Sephadex G-75 gel exclusion chromatography and cellulose chromatography (medium fibers). Subsequently, purification was confirmed by polyacrylamide gel electrophoresis, and the detection of killer activity was performed in solid YEPD-methylene blue buffered with citrate-phosphate (0.1 M, pH 4.6). Toxin identification was performed by liquid chromatography-mass spectrometry. The results showed that the best protein precipitation method was 2:1 ethanol (vol/vol ethanol/supernatant). It was possible to observe the presence of enzymes with proteolytic activity, including ß-1,3-glucanase and chitinase. During the purification process, it was verified that the killer toxin produced by the yeast has a low-molecular-weight protein belonging to the ubiquitin family, which presents killer activity against P. digitatum and G. citri-aurantii.
Assuntos
Aureobasidium/metabolismo , Agentes de Controle Biológico/isolamento & purificação , Proteínas Fúngicas/isolamento & purificação , Sequência de Aminoácidos , Antibiose , Aureobasidium/fisiologia , Agentes de Controle Biológico/química , Agentes de Controle Biológico/metabolismo , Agentes de Controle Biológico/farmacologia , Quitinases/metabolismo , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/farmacologia , Fungicidas Industriais/química , Fungicidas Industriais/isolamento & purificação , Fungicidas Industriais/metabolismo , Fungicidas Industriais/farmacologia , Geotrichum/efeitos dos fármacos , Glucana 1,3-beta-Glucosidase/metabolismo , Penicillium/efeitos dos fármacos , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , ProteóliseRESUMO
The essential oil of basil (Ocimum basilicum) has significant biological activity against insect pests and can be extracted through various techniques. This work aimed to optimize and validate the extraction process of the essential oil of O. basilicum submitted to different drying temperatures of the leaves and extracted by the combination of a Clevenger method and ultrasound. The biological activity of the extracted oil under different conditions was evaluated for potential control of Sitophilus zeamais. The extraction method was optimized according to the sonication time by ultrasound (0, 8, 19, 31 and 38 min) and hydrodistillation (20, 30, 45, 60 and 70 min) and drying temperature (20, 30, 45, 60 and 70 °C). The bioactivity of the essential oil was assessed against adults of S. zeamais and the effects of each variable and its interactions on the mortality of the insects were evaluated. The best yield of essential oil was obtained with the longest sonication and hydrodistillation times and the lowest drying temperature of leaves. Higher toxicity of the essential oil against S. zeamais was obtained by the use of ultrasound for its extraction. The identification and the relative percentage of the compounds of the essential oil were performed with a gas chromatograph coupled to a mass selective detector. The performance of the method was assessed by studying selectivity, linearity, limits of detection (LOD) and quantification (LOQ), precision and accuracy. The LOD and LOQ values for linalool were 2.19 and 6.62 µg mL-1 and for estragole 2.001 and 6.063 µg mL-1, respectively. The coefficients of determination (R2) were >0.99. The average recoveries ranged between 71 and 106%, with coefficient of variation ≤6.4%.
Assuntos
Agentes de Controle Biológico , Besouros/crescimento & desenvolvimento , Ocimum basilicum/química , Óleos Voláteis , Controle Biológico de Vetores , Ondas Ultrassônicas , Animais , Agentes de Controle Biológico/química , Agentes de Controle Biológico/isolamento & purificação , Agentes de Controle Biológico/farmacologia , Óleos Voláteis/química , Óleos Voláteis/isolamento & purificação , Óleos Voláteis/farmacologiaRESUMO
The most commonly used biopesticides to control agricultural, forest and insect vectors of human diseases are derived from the bacterium Bacillus thuringiensis, which begins to produce Cry and Cyt insecticidal proteins during the onset of the sporulation phase. Some B. thuringiensis strains also produce S-layer proteins that are toxic to certain pests. S-layer proteins are the most abundant proteins in bacteria and archaea. This proteins' key trait to design high performace processes for mass production is their continuous expression during the vegetative phase, unlike Cry and Cyt, which are restricted to the sporulation phase. In this work, a S-layer protein expressed by the GP543 strain of B. thuringiensis that is toxic to the cattle tick Rhipicephalus microplus was mass produced using the batch culture fermentation technique. In addition, the spore-protein complex showed a mortality rate of 75% with a dose of 300 µg·mL-1 on adult females of R. microplus after fourteen days. The lethal concentration 50 was 69.7 µg·mL-1. The treatment also caused a decrease of 13% in the weight of the mass of oviposited eggs with 200 µg·mL-1 of the spore-protein complex and inhibition of the hatching of eggs from 80 to 92%. Therefore, this could be a good option for controlling this parasite. The advantages of S-layer protein synthesis are focused on the production of a new generation of proteins in pest control. This is the first report on the mass production of an S-layer protein that is responsible for toxicity.
Assuntos
Bacillus thuringiensis/química , Técnicas Bacteriológicas/métodos , Agentes de Controle Biológico/isolamento & purificação , Microbiologia Industrial/métodos , Glicoproteínas de Membrana/isolamento & purificação , Rhipicephalus/efeitos dos fármacos , Animais , Anticorpos Antibacterianos/biossíntese , Bacillus thuringiensis/efeitos dos fármacos , Bacillus thuringiensis/crescimento & desenvolvimento , Bacillus thuringiensis/metabolismo , Agentes de Controle Biológico/toxicidade , Biomassa , Reatores Biológicos , Bovinos , Meios de Cultura/farmacologia , Feminino , Fermentação , Glicoproteínas de Membrana/imunologia , Glicoproteínas de Membrana/toxicidade , Oviposição/efeitos dos fármacos , Óvulo/efeitos dos fármacos , Coelhos , Esporos BacterianosRESUMO
Myzus persicae Sulzer (Hemiptera: Aphididae), is a generalist cosmopolitan insect that infests more than 400 plant species of 40 different families and is one of the major pests infesting potato crops. It causes direct damage and also spread plant viruses. The intensive use of synthetic insecticide to control aphids has led to resistant populations. Therefore, there is a need to develop biopesticides for effective control that minimizes environmental hazards. The bacteria Bacillus amyloliquefaciens is recognized as a producer of a variety of bioactive compounds. The aim here was to evaluate the aphicidal effect of B. amyloliquefaciens strains, CBMDDrag3, PGPBacCA2, and CBMDLO3, and their metabolites on the mortality and fecundity of M. persicae. Cells suspensions, heat-killed cell suspensions, cell-free supernatants, or isolated lipopeptide fractions from B. amyloliquefaciens strains were offered to aphids through artificial diets. The isolated lipopeptide fractions composed mainly of kurstakins, surfactins, iturins, and fengycins, when were administrated through diets, had no aphicidal effect against M. persicae. However, aphids fed on diets with whole cell suspensions and its cell-free supernatant of all three bacteria strains resulted in 100% mortality of adult aphids and nymphs. Specially, B. amyloliquefaciens CBMDLO3, has an effective aphicidal effect on M. persicae, used both bacterial cells and their metabolites. Moreover, heat-killed cells of B. amyloliquefaciens CBMDLO3 also had aphicidal action, although the aphid mortality was lower than on diet with living bacteria. Therefore, these results propose that B. amyloliquefaciens, could function as a novel eco-friendly biopesticide for the control of M. persicae.
Assuntos
Afídeos/efeitos dos fármacos , Afídeos/microbiologia , Bacillus amyloliquefaciens/metabolismo , Controle Biológico de Vetores , Animais , Bacillus amyloliquefaciens/isolamento & purificação , Agentes de Controle Biológico/isolamento & purificação , Agentes de Controle Biológico/metabolismo , Agentes de Controle Biológico/farmacologia , Feminino , Controle de Insetos/métodos , Inseticidas/isolamento & purificação , Inseticidas/metabolismo , Inseticidas/farmacologia , Lipopeptídeos/isolamento & purificação , Lipopeptídeos/metabolismo , Lipopeptídeos/farmacologia , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controleRESUMO
Leaf blast is the main rice disease in the world causing significant losses in productivity. Blast integrate management (BIM) requires the use of genetic resistance, cultural practices, and chemical control, although for sustainable BIM, the insertion of biological agents may be the fourth component for. The objective of this work was to test three formulations of Burkholderia pyrrocinia (BRM32113) previously selected and to verify the effectiveness in resistance induction and blast control in rice. Two experiments were carried out, in a completely randomized design with three replications, in the greenhouse (E1 and E2). E1 aimed to select the best treatment for suppressing leaf blast severity and activating plant defense mechanisms. It was composed of 8 treatments: (1) formulated 11+ B. pyrrocina × Magnaporthe oryzae; (2) formulated 17+ B. pyrrocina × M. oryzae; (3) formulated 32+ B. pyrrocina × M. oryzae; (4) formulated 11 × M. oryzae; (5) B. pyrrocinia 17 × M. oryzae; (6) formulated 32 × M. oryzae; (7) B. pyrrocina × M. oryzae; (8) M. oryzae; (9) control (water). E2 aimed to investigate the effect of the best treatments, for the promotion of plant growth and suppression of leaf blast by calculating AUDPC. It was composed of 6 treatments: (1) formulated 11+ B. pyrrocina × M. oryzae; (2) formulated 32+ B. pyrrocina × M. oryzae; (3) formulated 11 × M. oryzae; (4) formulated 32 × M. oryzae; (5) B. pyrrocina × M. oryzae; (6) water. And after, we did two assays aimed to localize this biological agent after application at seed, soil, and rice plant. In E1, formulated 11+ B. pyrrocinia and 32+ formulated and B. pyrrocina were the best, suppressing leaf blast by up to 97% and providing the significant increase of the enzymes ß-1,3-glucanase, chitinase, phenylalanine ammonia lyase, lipoxygenase, and salicylic acid at 24 h and 48 h after inoculation with M. oryzae. In E2, treatments formulated 11+ B. pyrrocinia, formulated 32+ B. pyrrocinia, and B. pyrrocina provided more significant increases in growth promotion and reduced area under disease progress curve. B. pyrrocinia was detected in the rice plant for 18 days, predominantly in the root system (internal and external). The use of B. pyrrocinia formulations based on sugarcane molasses and glycerol can be an essential strategy for sustainable management. Although all the benefits come from these sustainable formulations, the adoption by commercial biological segment depends on an established formulation process. It seems that all the results showed here by this research will be readily assimilated by startups of the organic segment.
Assuntos
Agentes de Controle Biológico/farmacologia , Burkholderia , Resistência à Doença/efeitos dos fármacos , Magnaporthe , Oryza/microbiologia , Doenças das Plantas/prevenção & controle , Agentes de Controle Biológico/isolamento & purificação , Burkholderia/metabolismo , Magnaporthe/crescimento & desenvolvimento , Oryza/enzimologia , Doenças das Plantas/microbiologia , Folhas de Planta/enzimologia , Folhas de Planta/microbiologia , Distribuição Aleatória , Ácido Salicílico/metabolismoRESUMO
Plants are colonized by diverse microorganisms that can substantially impact their health and growth. Understanding bacterial diversity and the relationships between bacteria and phytopathogens may be key to finding effective biocontrol agents. We evaluated the bacterial community associated with anthracnose symptomatic and asymptomatic leaves of guarana, a typical tropical crop. Bacterial communities were assessed through culture-independent techniques based on extensive 16S rRNA sequencing, and cultured bacterial strains were evaluated for their ability to inhibit the growth of Colletotrichum sp. as well as for enzyme and siderophore production. The culture-independent method revealed that Proteobacteria was the most abundant phylum, but many sequences were unclassified. The emergence of anthracnose disease did not significantly affect the bacterial community, but the abundance of the genera Acinetobacter, Pseudomonas and Klebsiella were significantly higher in the symptomatic leaves. In vitro growth of Colletotrichum sp. was inhibited by 11.38% of the cultured bacterial strains, and bacteria with the highest inhibition rates were isolated from symptomatic leaves, while asymptomatic leaves hosted significantly more bacteria that produced amylase and polygalacturonase. The bacterial isolate Bacillus sp. EpD2-5 demonstrated the highest inhibition rate against Colletotrichum sp., whereas the isolates EpD2-12 and FD5-12 from the same genus also had high inhibition rates. These isolates were also able to produce several hydrolytic enzymes and siderophores, indicating that they may be good candidates for the biocontrol of anthracnose. Our work demonstrated the importance of using a polyphasic approach to study microbial communities from plant diseases, and future work should focus on elucidating the roles of culture-independent bacterial communities in guarana anthracnose disease.
Assuntos
Antibiose/fisiologia , Agentes de Controle Biológico/isolamento & purificação , Colletotrichum/crescimento & desenvolvimento , Paullinia/microbiologia , Proteobactérias/isolamento & purificação , Acinetobacter/classificação , Acinetobacter/genética , Acinetobacter/isolamento & purificação , Amilases/metabolismo , Antracose/microbiologia , Bacillus/classificação , Bacillus/genética , Bacillus/isolamento & purificação , Klebsiella/classificação , Klebsiella/genética , Klebsiella/isolamento & purificação , Microbiota , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Poligalacturonase/metabolismo , Proteobactérias/classificação , Proteobactérias/genética , Pseudomonas/classificação , Pseudomonas/genética , Pseudomonas/isolamento & purificação , RNA Ribossômico 16S/genética , Floresta Úmida , Sideróforos/metabolismoRESUMO
Alphitobius diaperinus is an important pathogen with worldwide distribution that causes severe economic loss of efficiency in broilers. This study evaluates the potential of organic extracts of two strains entomopathogenic fungus Beauveria bassiana (CG71 and UNI40) as a biocontrol agent on A. diaperinus and promotes the phytochemical investigation. The effective percentages of mortalities were 95.97% (UNI40 methanolic extract), 69.23, 64.64, and 50.39% (CG 71 methanolic, ethyl acetate and butanol extracts). However, there was a decrease in the lesser mealworms susceptibility in relation to the use of insecticides and extracts. The metabolites 5-hydroxymethyl-2-furanoic acid, dipicolinic acid and monomethyl dipicolinate were isolated from ethyl acetate extract, and ß-adenosine of butanolic extract of B. bassiana CG 71. In addition, the cyclodepsipeptides were identified in methanolic extracts of the two strains. The insecticide activity results indicated that the B. bassiana extracts are an alternative to A. diaperinus control.
Assuntos
Beauveria/patogenicidade , Agentes de Controle Biológico/isolamento & purificação , Besouros/efeitos dos fármacos , Animais , Agentes de Controle Biológico/farmacologia , Galinhas , Inseticidas , Tenebrio/efeitos dos fármacosRESUMO
Plant extracts can provide a viable alternative to controlling many crop pests. This study sought to assess the efficacy of vegetable extracts of the unripe fruits of Ilex paraguariensis (yerba maté) for chemical control of the channeled apple snail (Pomacea canaliculata) and of non-target species as the South American catfish (Rhamdia quelen) under laboratory conditions. In P. canaliculata, the LC50 of the decoction extract was 31.39 mg.L-1 and the LT50 was over 26 h. The LC50 of the butanol extract was 24.75 mg.L-1 and the LT50 was in the range of 28 to 32 h. In juvenile R. quelen, the LC50 of the decoction was 17.98 mg.L-1 and the LT50 was in the range of 10-12 h. These extracts are particularly attractive considering the source of compounds and their effectiveness as molluscicides.
Assuntos
Agentes de Controle Biológico/toxicidade , Frutas/toxicidade , Ilex paraguariensis/química , Extratos Vegetais/toxicidade , Caramujos/efeitos dos fármacos , Animais , Agentes de Controle Biológico/química , Agentes de Controle Biológico/isolamento & purificação , Peixes-Gato , Frutas/química , Dose Letal Mediana , Extratos Vegetais/química , SolventesRESUMO
Tomato crops can be affected by several infectious diseases produced by bacteria, fungi, and oomycetes. Four phytopathogens are of special concern because of the major economic losses they generate worldwide in tomato production; Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato, causative agents behind two highly destructive diseases, bacterial canker and bacterial speck, respectively; fungus Fusarium oxysporum f. sp. lycopersici that causes Fusarium Wilt, which strongly affects tomato crops; and finally, Phytophthora spp., which affect both potato and tomato crops. Polygodial (1), drimenol (2), isonordrimenone (3), and nordrimenone (4) were studied against these four phytopathogenic microorganisms. Among them, compound 1, obtained from Drimys winteri Forst, and synthetic compound 4 are shown here to have potent activity. Most promisingly, the results showed that compounds 1 and 4 affect Clavibacter michiganensis growth at minimal inhibitory concentrations (MIC) values of 16 and 32 µg/mL, respectively, and high antimycotic activity against Fusarium oxysporum and Phytophthora spp. with MIC of 64 µg/mL. The results of the present study suggest novel treatment alternatives with drimane compounds against bacterial and fungal plant pathogens.
Assuntos
Antibacterianos/química , Agentes de Controle Biológico/química , Fungicidas Industriais/química , Sesquiterpenos/química , Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Agentes de Controle Biológico/isolamento & purificação , Fungicidas Industriais/isolamento & purificação , Fungicidas Industriais/farmacologia , Fusarium/efeitos dos fármacos , Solanum lycopersicum/microbiologia , Phytophthora/efeitos dos fármacos , Casca de Planta/química , Doenças das Plantas/microbiologia , Doenças das Plantas/terapia , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Sesquiterpenos/isolamento & purificação , Traqueófitas/químicaRESUMO
Control of fungal plant diseases by using naturally occurring non-pathogenic microorganisms represents a promising approach to biocontrol agents. This study reports the isolation, characterization, and fungal antagonistic activity of actinobacteria from forage soils in the Flooding Pampa, Argentina. A total of 32 saprophytic strains of actinobacteria were obtained by different isolation methods from rhizospheric soil of Lotus tenuis growing in the Salado River Basin. Based on physiological traits, eight isolates were selected for their biocontrol-related activities such as production of lytic extracellular enzymes, siderophores, hydrogen cyanide (HCN), and antagonistic activity against Cercospora sojina, Macrophomia phaseolina, Phomopsis sp., Fusarium oxysporum, and Fusarium verticilloides. These actinobacteria strains were characterized morphologically, physiologically, and identified by using molecular techniques. The characterization of biocontrol-related activities in vitro showed positive results for exoprotease, phospholipase, fungal growth inhibition, and siderophore production. However, none of the strains was positive for the production of hydrogen cyanide (HCN). Streptomyces sp. MM140 presented the highest index for biocontrol, and appear to be promising pathogenic fungi biocontrol agents. These results show the potential capacity of actinobacteria isolated from forage soils in the Argentine Pampas lowlands as promising biocontrol agents, and their future agronomic applications.
Assuntos
Actinobacteria/isolamento & purificação , Actinobacteria/fisiologia , Antibiose , Agentes de Controle Biológico/isolamento & purificação , Fabaceae/microbiologia , Rizosfera , Microbiologia do Solo , Actinobacteria/química , Actinobacteria/genética , Antifúngicos/farmacologia , Argentina , Ascomicetos , Produtos Biológicos/farmacologia , Fusarium/efeitos dos fármacos , Cianeto de Hidrogênio/metabolismo , Doenças das Plantas/microbiologia , Sideróforos/biossíntese , Streptomyces/isolamento & purificaçãoRESUMO
UNLABELLED: In this study, yeasts and lactic acid bacteria (LAB) were isolated from coffee fruits and identified via biochemical and molecular approaches. The isolates represented the Pichia, Debaryomyces, Candida, Clavispora, Yarrowia, Sporobolomyces, Klyveromyces, Torulaspora and Lactobacillus genera. Four isolates, namely Pichia fermentans LPBYB13, Sporobolomyces roseus LPBY7E, Candida sp. LPBY11B and Lactobacillus brevis LPBB03, were found to have the greatest antagonist activity against an ochratoxigenic strain of Aspergillus westerdijkiae on agar tests and were selected for further characterization. Applications of P. fermentans LPBYB13 in coffee cherries artificially contaminated with A. westerdijkiae showed efficacy in reducing ochratoxin A (OTA) content up to 88%. These results highlight that P. fermentans LPBYB13 fulfils the principle requirements of an efficient biological control of aflatoxigenic fungi in coffee beans and may be seen as a reliable candidate for further validation in field conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Studies based on microbial ecology and antagonistic interactions are important for the development of new strategies in controlling aflatoxin contamination of crops and are relevant to further biotechnological applications. This study shows that coffee fruit is a potential source for the isolation of microbial strains with antifungal ability. A new yeast strain, Pichia fermentans LPBYB13, showed efficacy in reducing growth and ochratoxin A production of Aspergillus westerdijkiae in coffee beans. Our results should encourage the use of this yeast strain on a large scale for biocontrol of aflatoxigenic fungi in coffee beans.
Assuntos
Aflatoxinas/biossíntese , Antifúngicos/isolamento & purificação , Aspergillus/crescimento & desenvolvimento , Agentes de Controle Biológico/isolamento & purificação , Café/microbiologia , Contaminação de Alimentos/prevenção & controle , Ocratoxinas/biossíntese , Agentes de Controle Biológico/metabolismo , Candida/isolamento & purificação , Candida/metabolismo , Frutas/microbiologia , Ácido Láctico/metabolismo , Levilactobacillus brevis/isolamento & purificação , Levilactobacillus brevis/metabolismo , Pichia/isolamento & purificação , Pichia/metabolismoRESUMO
One of the most economically important bacterial pathogens of plants and plant products is Dickeya dadantii. This bacterium causes soft rot disease in tubers and other parts of the potato and other plants of the Solanaceae family. The application of restricted host range bacteriophages as biocontrol agents has recently gained widespread interest. This study purposed to isolate the infectious agent of the potato and evaluate its biocontrol by bacteriophages. Two phytopathogenic strains were isolated from infected potatoes, identified based on biochemical and 16S rRNA gene sequencing, and submitted to GenBank as D. dadantii strain pis3 (accession no. HQ423668) and D. dadantii strain sip4 (accession no. HQ423669). Their bacteriophages were isolated from Caspian Sea water by enriching the water filtrate with D. dadantii strains as hosts using spot or overlay methods. On the basis of morphotypes, the isolated bacteriophages were identified as members of the Myoviridae and Siphoviridae families and could inhibit the growth of antibiotic resistant D. dadantii strains in culture medium. Moreover, in Dickeya infected plants treated with bacteriophage, no disease progression was detected. No significant difference was seen between phage-treated and control plants. Thus, isolated bacteriophages can be suggested for the biocontrol of plant disease caused by Dickeya strains.
Assuntos
Bacteriófagos/isolamento & purificação , Agentes de Controle Biológico/isolamento & purificação , Dickeya chrysanthemi/crescimento & desenvolvimento , Dickeya chrysanthemi/virologia , Doenças das Plantas/microbiologia , Solanum tuberosum/microbiologia , Bacteriófagos/classificação , Sequência de Bases , Agentes de Controle Biológico/classificação , DNA Bacteriano/genética , Dickeya chrysanthemi/efeitos dos fármacos , Dickeya chrysanthemi/isolamento & purificação , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Myoviridae/classificação , Myoviridae/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Siphoviridae/classificação , Siphoviridae/isolamento & purificaçãoRESUMO
This study was initially designed to evaluate the differential susceptibility of three soybean-attacking pentatomids to the entomopathogenic fungus Beauveria bassiana in standardized bioassays. Euschistus heros (Eh) was shown to be significantly less susceptible than Chinavia ubica (Cu), whereas Dichelops melacanthus (Dm) adults were highly susceptible to fungal infections. A deeper look at the mechanisms involved in the possible role of volatiles from metathoracic glands on fungal infections was undertaken, and gland extracts from Nezara viridula (Nv), a species known for its resilience to fungal infections, were also included in the assays. Atmospheres with volatiles from pentatomids with very low-susceptibility to B. bassiana infections (Eh and Nv) had a significant effect on speed of germination as shown in counts performed up to 22h post-inoculation, by which time 0.1 (control), 0.6 (Dm), 17.9 (Cu), 32.6 (Eh), and 43.4% (Nv) of conidia had not germinated. The fungistatic (inhibitory) and fungicidal (lethal) effects of Eh and Nv volatile-rich atmospheres were subsequently quantified in Petri dishes with either PDA or PDA medium amended with carbendazim, which allowed germination rates to be determined at 18 and 48h post-inoculation, respectively. As opposed to control, Eh volatile-rich atmosphere had a clear fungistatic effect, since germination rate was only 27.4% within 18h, but reached 99.4% at 48h post-inoculation. For Nv volatile-rich atmospheres, only 15.1% of conidia germinated within 18h, and by 48h post-inoculation, approx. 18% of conidia were unviable (neither germ tubes nor intumescence), whereas in the control treatment rates were >99% at both reading times. Therefore, the gaseous phase of defensive secretions from fungus-resilient pentatomids possess a strong inhibitory effect and may display a less pronounced lethal effect on fungal germination, as was the case for Nv.
Assuntos
Beauveria/efeitos dos fármacos , Fungicidas Industriais/farmacologia , Heterópteros/química , Animais , Beauveria/crescimento & desenvolvimento , Agentes de Controle Biológico/química , Agentes de Controle Biológico/isolamento & purificação , Agentes de Controle Biológico/farmacologia , Fungicidas Industriais/química , Fungicidas Industriais/isolamento & purificação , Heterópteros/microbiologia , Esporos Fúngicos/efeitos dos fármacosRESUMO
One of the most economically important bacterial pathogens of plants and plant products is
Assuntos
Bacteriófagos/isolamento & purificação , Agentes de Controle Biológico/isolamento & purificação , Dickeya chrysanthemi/crescimento & desenvolvimento , Dickeya chrysanthemi/virologia , Doenças das Plantas/microbiologia , Solanum tuberosum/microbiologia , Sequência de Bases , Bacteriófagos/classificação , Agentes de Controle Biológico/classificação , DNA Bacteriano/genética , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Myoviridae/classificação , Myoviridae/isolamento & purificação , Dickeya chrysanthemi/efeitos dos fármacos , Dickeya chrysanthemi/isolamento & purificação , /genética , Análise de Sequência de DNA , Siphoviridae/classificação , Siphoviridae/isolamento & purificaçãoRESUMO
One of the most economically important bacterial pathogens of plants and plant products is