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1.
PLoS One ; 15(8): e0233665, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32804955

RESUMO

Oligomycins are macrolide antibiotics, produced by Streptomyces spp. that show antagonistic effects against several microorganisms such as bacteria, fungi, nematodes and the oomycete Plasmopara viticola. Conidiogenesis, germination of conidia and formation of appressoria are determining factors pertaining to pathogenicity and successful diseases cycles of filamentous fungal phytopathogens. The goal of this research was to evaluate the in vitro suppressive effects of two oligomycins, oligomycin B and F along with a commercial fungicide Nativo® 75WG on hyphal growth, conidiogenesis, conidial germination, and appressorial formation of the wheat blast fungus, Magnaporthe oryzae Triticum (MoT) pathotype. We also determined the efficacy of these two oligomycins and the fungicide product in vivo in suppressing wheat blast with a detached leaf assay. Both oligomycins suppressed the growth of MoT mycelium in a dose dependent manner. Between the two natural products, oligomycin F provided higher inhibition of MoT hyphal growth compared to oligomycin B with a minimum inhibitory concentration of 0.005 and 0.05 µg/disk, respectively. The application of the compounds completely halted conidial formation of the MoT mycelium in agar medium. Further bioassays showed that these compounds significantly inhibited MoT conidia germination and induced lysis. The compounds also caused abnormal germ tube formation and suppressed appressorial formation of germinated spores. Interestingly, the application of these macrolides significantly inhibited wheat blast on detached leaves of wheat. This is the first report on the inhibition of mycelial growth, conidiogenesis, germination of conidia, deleterious morphological changes in germinated conidia, and suppression of blast disease of wheat by oligomycins from Streptomyces spp. Further study is needed to unravel the precise mode of action of these natural compounds and consider them as biopesticides for controlling wheat blast.


Assuntos
Magnaporthe/efeitos dos fármacos , Magnaporthe/patogenicidade , Oligomicinas/farmacologia , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Triticum/microbiologia , Agentes de Controle Biológico/farmacologia , Grão Comestível/microbiologia , Microbiologia de Alimentos , Fungicidas Industriais/farmacologia , Hifas/efeitos dos fármacos , Hifas/crescimento & desenvolvimento , Magnaporthe/crescimento & desenvolvimento , Micélio/efeitos dos fármacos , Micélio/crescimento & desenvolvimento , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimento
2.
PLoS Negl Trop Dis ; 14(8): e0008542, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32810151

RESUMO

Presently, the principal tools to combat malaria are restricted to killing the parasite in infected people and killing the mosquito vector to thwart transmission. While successful, these approaches are losing effectiveness in view of parasite resistance to drugs and mosquito resistance to insecticides. Clearly, new approaches to fight this deadly disease need to be developed. Recently, one such approach-engineering mosquito resident bacteria to secrete anti-parasite compounds-has proven in the laboratory to be highly effective. However, implementation of this strategy requires approval from regulators as it involves introduction of recombinant bacteria into the field. A frequent argument by regulators is that if something unexpectedly goes wrong after release, there must be a recall mechanism. This report addresses this concern. Previously we have shown that a Serratia bacterium isolated from a mosquito ovary is able to spread through mosquito populations and is amenable to be engineered to secrete anti-plasmodial compounds. We have introduced a plasmid into this bacterium that carries a fluorescent protein gene and show that when cultured in the laboratory, the plasmid is completely lost in about 130 bacterial generations. Importantly, when these bacteria were introduced into mosquitoes, the bacteria were transmitted from one generation to the next, but the plasmid was lost after three mosquito generations, rendering the bacteria non-recombinant (wild type). Furthermore, no evidence was obtained for horizontal transfer of the plasmid to other bacteria either in culture or in the mosquito. Prior to release, it is imperative to demonstrate that the genes that thwart parasite development in the mosquito are safe to the environment. This report describes a methodology to safely achieve this goal, utilizing transient expression from a plasmid that is gradually lost, returning the bacterium to wild type status.


Assuntos
Anopheles/microbiologia , Agentes de Controle Biológico/farmacologia , Mosquitos Vetores/microbiologia , Serratia/genética , Serratia/metabolismo , Animais , Bactérias/genética , Bactérias/metabolismo , Transmissão de Doença Infecciosa , Feminino , Malária , Masculino , Ovário/microbiologia , Plasmídeos/genética
3.
PLoS Negl Trop Dis ; 14(7): e0008479, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32687496

RESUMO

The existing mosquito pesticide repertoire faces great challenges to sustainability, and new classes of pesticides are vitally needed to address established and emerging mosquito-borne infectious diseases. RNA interference- (RNAi-) based pesticides are emerging as a promising new biorational mosquito control strategy. In this investigation, we describe characterization of an interfering RNA pesticide (IRP) corresponding to the mosquito Shaker (Sh) gene, which encodes an evolutionarily conserved voltage-gated potassium channel subunit. Delivery of the IRP to Aedes aegypti adult mosquitoes in the form of siRNA that was injected or provided as an attractive toxic sugar bait (ATSB) led to Sh gene silencing that resulted in severe neural and behavioral defects and high levels of adult mortality. Likewise, when provided to A. aegypti larvae in the form of short hairpin RNA (shRNA) expressed in Saccharomyces cerevisiae (baker's yeast) that had been formulated into a dried inactivated yeast tablet, the yeast IRP induced neural defects and larval death. Although the Sh IRP lacks a known target site in humans or other non-target organisms, conservation of the target site in the Sh genes of multiple mosquito species suggested that it may function as a biorational broad-range mosquito insecticide. In support of this, the Sh IRP induced both adult and larval mortality in treated Aedes albopictus, Anopheles gambiae, and Culex quinquefasciatus mosquitoes, but was not toxic to non-target arthropods. These studies indicated that IRPs targeting Sh could one day be used in integrated biorational mosquito control programs for the prevention of multiple mosquito-borne illnesses. The results of this investigation also suggest that the species-specificity of ATSB technology, a new paradigm for vector control, could be enhanced through the use of RNAi-based pesticides.


Assuntos
Agentes de Controle Biológico/farmacologia , Culicidae/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Oligonucleotídeos/farmacologia , Superfamília Shaker de Canais de Potássio/metabolismo , Animais , DNA , Daphnia , Feminino , Inativação Gênica , Larva/efeitos dos fármacos , RNA Interferente Pequeno , Superfamília Shaker de Canais de Potássio/genética
4.
Arch Razi Inst ; 75(1): 123-130, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32292010

RESUMO

Agaricus bisporus mushrooms are well known for their nutritional and medicinal values. A. bisporus is a source of protein (about 40% on a dry basis), ergosterol, several minerals, carbohydrate, and fat. The present study was conducted to investigate the effect of A. bisporus S-II extracts on human pathogenic bacteria in-vitro condition. Totally, three human pathogenic bacterial strains (MTCC culture type) were procured from the Institute of Microbial Technology, India. Out of these three bacterial strains, one was Gram-negative (namely P. aeruginosa MTCC741), and the other two were Gram-positive (B. cereus MTCC9786 and S. aureus MTCC740). Microdilution assay was applied for the evaluation of the minimum inhibitory concentration (MIC). The highest antimicrobial activity was observed in methanol extract (26.5%) against S. aureus MTCC740, compared to ethanol extract (17%). Similar results were obtained for P. aeruginosa MTCC741 (21.8%) and B. cereus MTCC9786 (15%) in methanol extract. Least microbial growth inhibition observed for B. cereus MTCC9786 (13.82%) followed by P. aeruginosa MTCC741 (14%), compared to control in ethanol extract. The highest antimicrobial activity up to 17% with ethanolic extracts recorded against S. aureus MTCC740. The MIC results in microtitre plates showed the growth inhibition of P. aeruginosa MTCC741 and S. aureus MTCC740 at extract concentrations of 15 mg/ml and 20 mg/ml, respectively. However, no MIC detected for B. cereus MTCC9786 below 20 mg/ml extract concentration. Regarding minimum bactericidal concentration, the bactericidal value for P. aeruginosa MTCC741 and S. aureus MTCC740 was obtained at 10 mg/ml concentration. The present study indicated that the extracts of the A. bisporus S-II mushrooms had promising antimicrobial activities against the tested organisms.


Assuntos
Agaricus/química , Bacillus cereus/efeitos dos fármacos , Agentes de Controle Biológico/farmacologia , Extratos Vegetais/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana
5.
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
6.
Arch Insect Biochem Physiol ; 104(2): e21673, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32212396

RESUMO

Three-domain Cry toxins from the bacterium Bacillus thuringiensis (Bt) are increasingly used in agriculture to replace chemical insecticides in pest control. Most chemical insecticides kill pest insects swiftly, but are also toxic to beneficial insects and other species in the agroecosystem. Cry toxins enjoy the advantages of high selectivity and the possibility of the application by sprays or transgenic plants. However, these benefits are offset by the limited host range and the evolution of resistance to Bt toxins by insect pests. Understanding how Bt toxins kill insects will help to understand the nature of both problems. The recent realization that ABC transporters play a central role in the killing mechanism will play an important role in devising solutions.


Assuntos
Bacillus thuringiensis/química , Toxinas Bacterianas/farmacologia , Agentes de Controle Biológico/farmacologia , Evolução Biológica , Insetos/efeitos dos fármacos , Controle Biológico de Vetores , Animais , Toxinas Bacterianas/toxicidade , Agentes de Controle Biológico/toxicidade , Insetos/microbiologia , Plantas Geneticamente Modificadas/microbiologia
7.
Appl Environ Microbiol ; 86(11)2020 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-32220845

RESUMO

Given the continued high prevalence of mosquito-transmitted diseases, there is a clear need to develop novel disease and vector control strategies. Biopesticides of microbial origin represent a promising source of new approaches to target disease-transmitting mosquito populations. Here, we describe the development and characterization of a novel mosquito biopesticide, derived from an air-dried, nonlive preparation of the bacterium Chromobacterium sp. Panama (family: Neisseriaceae). This preparation rapidly and effectively kills the larvae of prominent mosquito vectors, including the dengue and Zika vector Aedes aegypti and the human malaria vector Anopheles gambiae During semi-field trials in Puerto Rico, we observed high efficacy of the biopesticide against field-derived A. aegypti populations, and against A. aegypti and Culex species larvae in natural breeding water, indicating the suitability of the biopesticide for use under more natural conditions. In addition to high efficacy, the nonlive Csp_P biopesticide has a low effective dose, a long shelf life, and high heat stability and can be incorporated into attractive larval baits, all of which are desirable characteristics for a biopesticide.IMPORTANCE We have developed a novel preparation to kill mosquitoes from an abundant soil bacterium, Chromobacterium sp. Panama. This preparation is an air-dried powder containing no live bacteria, and it can be incorporated into an attractive bait and fed directly to mosquito larvae. We demonstrate that the preparation has broad spectrum activity against the larval form of the mosquitoes responsible for the transmission of malaria and the dengue, chikungunya, yellow fever, West Nile, and Zika viruses, as well as mosquito larvae that are already resistant to commonly used mosquitocidal chemicals. Our preparation possesses many favorable traits: it kills at a low dosage, and it does not lose activity when exposed to high temperatures, all of which suggest that this preparation could eventually become an effective new tool for controlling mosquitoes and the diseases they spread.


Assuntos
Aedes/efeitos dos fármacos , Anopheles/efeitos dos fármacos , Agentes de Controle Biológico/farmacologia , Chromobacterium/química , Culex/efeitos dos fármacos , Inseticidas/farmacologia , Aedes/genética , Animais , Anopheles/genética , Culex/genética , Larva/efeitos dos fármacos , Larva/genética , Porto Rico
8.
Microbiol Res ; 236: 126451, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32146294

RESUMO

Burkholderia species have different lifestyles establishing mutualist or pathogenic associations with plants and animals. Changes in the ecological behavior of these bacteria may depend on genetic variations in response to niche adaptation. Here, we studied 15 Burkholderia strains isolated from different environments with respect to genetic and phenotypic traits. By Multilocus Sequence Analysis (MLSA) these isolates fell into 6 distinct groups. MLSA clusters did not correlate with strain antibiotic sensitivity, but with the bacterial ability to produce antimicrobial compounds and control orchid necrosis. Further, the B. seminalis strain TC3.4.2R3, a mutualistic bacterium, was inoculated into orchid plants and the interaction with the host was evaluated by analyzing the plant response and the bacterial oxidative stress response in planta. TC3.4.2R3 responded to plant colonization by increasing its own growth rate and by differential gene regulation upon oxidative stress caused by the plant, while reducing the plant's membrane lipid peroxidation. The bacterial responses to oxidative stress were recapitulated by bacterial exposure to the herbicide paraquat. We suggest that the ability of Burkholderia species to successfully establish in the rhizosphere correlates with genetic variation, whereas traits associated with antibiotic resistance are more likely to be categorized as strain specific.


Assuntos
Adaptação Biológica/genética , Infecções por Burkholderia , Burkholderia , Interações entre Hospedeiro e Microrganismos , Orchidaceae/microbiologia , Aclimatação/genética , Anti-Infecciosos/farmacologia , Agentes de Controle Biológico/farmacologia , Burkholderia/genética , Burkholderia/crescimento & desenvolvimento , Burkholderia/isolamento & purificação , Burkholderia/metabolismo , Resistência Microbiana a Medicamentos/genética , Endófitos/genética , Endófitos/crescimento & desenvolvimento , Endófitos/isolamento & purificação , Endófitos/metabolismo , Genes Bacterianos , Ilhas Genômicas , Genótipo , Peroxidação de Lipídeos , Tipagem de Sequências Multilocus , Orchidaceae/fisiologia , Estresse Oxidativo/genética , Fenótipo , Filogenia , Doenças das Plantas/microbiologia , Doenças das Plantas/terapia , RNA Ribossômico 16S/genética , Simbiose , Transcriptoma
9.
J Chem Ecol ; 46(3): 233-249, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31970605

RESUMO

Use of the first fish pheromone biopesticide, 3-keto petromyzonol sulfate (3kPZS) in sea lamprey (Petromyzon marinus) control requires an understanding of both how the amount 3kPZS applied to a trap relates to catch, and how that relationship varies among stream types. By conducting 3kPZS dose-response experiments over two years and across six varied trapping contexts, we conclude (1) that 3kPZS application is best standardized by how much is emitted from the trap instead of the fully mixed concentration achieved downstream, and (2) that 3kPZS is more effective in wide streams (>30 m). In wide streams, emission of 3kPZS at 50 mg hr.-1 from the trap increased capture rate by 10-15% as sea lamprey were 25-50% more likely to enter the trap after encounter. However, in narrow streams (< 15 m), 50 mg hr.-1 3kPZS generally reduced probabilities of upstream movement, trap encounter, and entrance. While 3kPZS significantly influenced upstream movement, encounter, and capture probabilities, these behaviors were also highly influenced by water temperature, stream width, sea lamprey length, and sex. This study highlights that a pheromone component in a stream environment does not ubiquitously increase trap catch in all contexts, but that where, how, and when the pheromone is applied has major impacts on whether it benefits or hinders trapping efforts.


Assuntos
Agentes de Controle Biológico/farmacologia , Ácidos Cólicos/farmacologia , Controle Biológico de Vetores/métodos , Petromyzon/fisiologia , Feromônios/farmacologia , Animais , Relação Dose-Resposta a Droga , Feminino , Masculino
10.
Microbiol Res ; 232: 126387, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31790975

RESUMO

Plants host a complex microbiota inside or outside their tissues, and phyllosphere microorganisms can be influenced by environmental, nutritional and agronomic factors. Rare sugars are defined as monosaccharides with limited availability in nature and they are metabolised by only few certain microbial taxa. Among rare sugars, tagatose (TAG) is a low-calories sweetener that stimulates and inhibits beneficial and pathogenic bacteria in the human gut microbiota, respectively. Based on this differential effect on human-associated microorganisms, we investigated the effect of TAG treatments on the grapevine phyllosphere microorganisms to evaluate whether it can engineer the microbiota and modify the ratio between beneficial and pathogenic plant-associated microorganisms. TAG treatments changed the structure of the leaf microbiota and they successfully reduced leaf infections of downy mildew (caused by Plasmopara viticola) and powdery mildew (caused by Erysiphe necator) under field conditions. TAG increased the relative abundance of indigenous beneficial microorganisms, such as some potential biocontrol agents, which could partially contribute to disease control. The taxonomic composition of fungal and bacterial leaf populations differed according to grapevine locations, therefore TAG effects on the microbial structure were influenced by the composition of the originally residing microbiota. TAG is a promising biopesticide that could shift the balance of pathogenic and beneficial plant-associated microorganisms, suggesting selective nutritional/anti-nutritional properties for some specific taxa. More specifically, TAG displayed possible plant prebiotic effects on the phyllosphere microbiota and this mechanism of action could represent a novel strategy that can be further developed for sustainable plant protection.


Assuntos
Agentes de Controle Biológico/farmacologia , Hexoses/farmacologia , Microbiota/efeitos dos fármacos , Folhas de Planta/microbiologia , Ascomicetos , Resistência à Doença , Engenharia Metabólica , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Açúcares , Vitis/imunologia , Vitis/microbiologia
11.
Microbiol Res ; 232: 126389, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31821969

RESUMO

This study describes the biocontrol potential of rhizobacteria against a range of fungal phytopathogens. Out of 227 bacteria isolated from the rhizosphere of maize, rice, wheat, potato, sunflower and soybean crops cultivated in different agro-ecological regions of Pakistan, 48 exhibited >60 % antifungal activity against Fusarium oxysporum, Fusarium moniliforme, Rhizoctonia solani, Colletotrichum gloeosporioides, Colletotrichum falcatum, Aspergillus niger, and Aspergillus flavus. The rhizobacteria inhibiting >65 % pathogen growth were selected for detailed molecular and in planta studies most of which were identified as Pseudomonas and Bacillus species based on 16S rRNA gene sequence analysis. Antifungal metabolites produced by these rhizobacteria analyzed through LCMS were identified as antibiotics (iturin, surfactins, fengycin, DAPG, Phenazine, etc.), cell wall degrading enzymes (protease, chitinase, and cellulase), plant growth promotion enzymes and hormones (indole-3-acetic acid, ACC-deaminase, phosphates, nitrogen fixation), N-acyl-homoserine lactones and siderophores. The growth room experiment validated the potential of these bacteria as biofertilizer and biopesticide agents. Of all, P. aeruginosa strain FB2 and B. subtilis strain RMB5 showed significantly higher potential as antagonistic plant-beneficial bacteria effective against a range of fungal phytopathogens. Both these bacteria can be used to develop a dual-purpose bacterial inoculum as biopesticide and biofertilizer. Rest of the antagonistic PGPR may be exploited for disease control in less-infested soils.


Assuntos
Antifúngicos/metabolismo , Antifúngicos/farmacologia , Bactérias/metabolismo , Fungos/efeitos dos fármacos , Rizosfera , Antibacterianos/metabolismo , Aspergillus flavus/efeitos dos fármacos , Aspergillus niger/efeitos dos fármacos , Bacillus/metabolismo , Bactérias/genética , Bactérias/isolamento & purificação , Biofilmes/crescimento & desenvolvimento , Agentes de Controle Biológico/metabolismo , Agentes de Controle Biológico/farmacologia , Colletotrichum/efeitos dos fármacos , Fusarium/efeitos dos fármacos , Cianeto de Hidrogênio/metabolismo , Cianeto de Hidrogênio/farmacologia , Ácidos Indolacéticos/metabolismo , Ácidos Indolacéticos/farmacologia , Fixação de Nitrogênio , Paquistão , Desenvolvimento Vegetal/efeitos dos fármacos , Desenvolvimento Vegetal/imunologia , Doenças das Plantas/microbiologia , Raízes de Plantas/microbiologia , Pseudomonas/metabolismo , Pseudomonas aeruginosa , Percepção de Quorum , RNA Ribossômico 16S/genética , Rhizoctonia/efeitos dos fármacos , Sideróforos/metabolismo , Sideróforos/farmacologia , Zea mays/microbiologia
12.
J Environ Sci Health B ; 55(2): 115-126, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31549910

RESUMO

The aim of this study was to produce Bacillus thuringiensis-based biopesticide using starch-producing industry wastewater (SIW) fortified with soybean medium and optimize the formulated product using different adjuvants. This study was necessary as low endotoxin concentration is obtained in formulated biopesticide when SIW alone is used as fermentation medium. The fermentation runs were conducted using SIW alone and SIW fortified with 25% soybean (w/v) medium in 2000 L and 150 L bioreactor, respectively. SIW supplemented with soybean medium showed an increase in cell count (from 1.95 × 108 to 1.65 × 109 CFU mL-1), spore synthesis (from 1.5 × 108 to 1.35 × 109 CFU mL-1) and endotoxin concentration (from 436 to 1170 µg mL-1) when compared to SIW medium alone. The fermented broth was concentrated using continuous centrifugation and adjuvants were added for biopesticide formulation in order to enhance its resistance against UV rays and rainfastness. Entomotoxicity of the formulation produced using fermented broth of SIW fortified with soybean (38,000 IU µL-1) was higher than that obtained by SIW medium alone (21,000 IU µL-1), commercial biopesticide Foray 76B (20,000 IU µL-1) and Btk sander's (12,500 IU µL-1).


Assuntos
Bacillus thuringiensis , Proteínas de Bactérias/metabolismo , Agentes de Controle Biológico/farmacologia , Meios de Cultura/química , Endotoxinas/metabolismo , Proteínas Hemolisinas/metabolismo , Inseticidas/farmacologia , Águas Residuárias/química , Animais , Bacillus thuringiensis/metabolismo , Agentes de Controle Biológico/metabolismo , Reatores Biológicos , Fermentação , Florestas , Mariposas , Chuva , Soja/química , Esporos Bacterianos , Amido/química , Raios Ultravioleta
13.
Arch Microbiol ; 202(2): 377-389, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31679043

RESUMO

Acidovorax citrulli, the gram-negative bacteria that causes bacterial fruit blotch (BFB), has been responsible for huge worldwide economic losses in watermelon and melon production since 1980. No commercial cultivar resistant to BFB has been reported. Of the two reported genotypes of A. citrulli, genotype I is the main causal agent of BFB in melon and genotype II causes disease in watermelon. After the isolation of the first bacteriophage against A. citrulli (ACP17), efforts have been made to isolate bacteriophages with wider host ranges by collecting samples from watermelon, pumpkin, and cucumber. The newly isolated phage ACPWH, belonging to the Siphoviridae family, has a head size of 60 ± 5 nm and tail size of 180 ± 5 nm, and can infect 39 out of 42 A. citrulli strains. ACPWH has genome size of 42,499 and GC content of 64.44%. Coating watermelon seeds with bacteriophage ACPWH before soil inoculation with A. citrulli resulted in 96% germination and survival, compared to 13% germination of uncoated control seeds. These results suggest that phage ACPWH may be an effective and low-cost biocontrol agent against BFB.


Assuntos
Agentes de Controle Biológico/farmacologia , Citrullus/microbiologia , Comamonadaceae/virologia , Doenças das Plantas/prevenção & controle , Siphoviridae/fisiologia , Frutas/microbiologia , Especificidade de Hospedeiro , Doenças das Plantas/microbiologia , Sementes/virologia , Siphoviridae/crescimento & desenvolvimento
14.
J Appl Microbiol ; 128(1): 255-264, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31541488

RESUMO

AIMS: To conduct molecular tagging of the biocontrol fungus Trichoderma asperellum strain T4 and elucidate its colonization patterns in soil. METHODS AND RESULTS: We constructed an expression vector harbouring a hygromycin B-resistant gene (hph) and an efficient green fluorescent protein (egfp) gene. By applying Agrobacterium AGL-1-mediated genetic transformation technology, we conducted molecular tagging of T. asperellum and monitored the colonization dynamics of T. asperellum in soil. The results of tracking five independent transformants of T. asperellum indicated that its expansion rates ranged from 4·7 to 6·8 cm week-1 . After inoculation in soil, the quantities of T. asperellum could be maintained at over 10 × 104  CFU per gram soil in the first year. In the third year after inoculation, the quantities of T. asperellum in soil were still higher than 1 × 103  CFU per gram soil. In addition, molecularly tagged T. asperellum in soil in the second year (i.e. 12 months) after inoculation could still reach the biocontrol effect on cucumber Rhizoctonia rot by more than 74%. CONCLUSION: Trichoderma asperellum strain T4 is capable of effectively colonizing in soil and surviving for more than 1 year. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has provided the scientific basis for applying T. asperellum as the biocontrol fungus for prevention and control of plant diseases.


Assuntos
Agentes de Controle Biológico , Microbiologia do Solo , Trichoderma/crescimento & desenvolvimento , Trichoderma/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Agentes de Controle Biológico/farmacologia , Contagem de Colônia Microbiana , Cucumis sativus/microbiologia , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Rhizoctonia/efeitos dos fármacos , Trichoderma/metabolismo
15.
J Appl Microbiol ; 128(1): 232-241, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31544331

RESUMO

AIM: The aim of this paper was to determine whether the quality of formulated Pseudomonas fluorescens Pf153 can be influenced by changes in fermentation conditions. In this study, the influence of the fermentation temperature on the growth and its consequence on shelf life, viability and biocontrol efficacy of freeze-dried cells of P. fluorescens Pf153 was investigated. METHODS AND RESULTS: Cells of P. fluorescens Pf153 were grown at 20 and 28°C in flasks and fermenter and harvested in the mid-log and the beginning of the stationary phase. The survival during storage of freeze-dried cells was tested at 25°C. Cells fermented at 20°C survived in storage better than those grown at 28°C, irrespective of the harvesting time. Compared to the untreated control, in in vitro tests Pf153 was in all production temperature/duration combinations significantly effective against all tested Botrytis cinerea strains. But no differences between temperature/duration combinations were found. In bioassay on detached Vicia faba leaves, it was found that young cells, when fermented at 28°C had a significant positive influence on the biocontrol efficacy. CONCLUSIONS: These results demonstrate that fermentation parameters have an influence on the performance and quality of a formulated product. SIGNIFICANCE AND IMPACT OF THE STUDY: Only limited numbers of biocontrol products based on antagonistic pseudomonads are on the market. This can be attributed to the lack of suitable formulated products with high numbers of viable cells and a good shelf life. Currently, only limited information on the influence of the fermentation on subsequent downstreaming process is available. Within this study, we focused on the influence of the two important parameters fermentation temperature and harvest time on survival, shelf life and biocontrol efficacy of P. fluorescens Pf153.


Assuntos
Agentes de Controle Biológico , Preservação Biológica/métodos , Pseudomonas fluorescens/fisiologia , Agentes de Controle Biológico/farmacologia , Botrytis/efeitos dos fármacos , Fermentação , Liofilização , Viabilidade Microbiana , Temperatura , Vicia faba/microbiologia
16.
J Appl Microbiol ; 128(1): 28-40, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31306569

RESUMO

Despite being the fastest growing sector, the modern aquaculture industry faces serious challenges such as the lack of protein source in feed, the susceptibility to pathogens, and deterioration in quality during culture and storage. Bacterial biomass is considered as a proper protein source for feed, and the beneficial bacterial species protect aquatic animals from infection or reduce spoilage of products. In this review, we summarized the application of beneficial bacteria to aquatic products, focusing mainly on the nutritional, anti-pathogenic, anti-spoilage and immunoregulatory functions of these bacteria. We then discussed the relationship between beneficial bacteria, intestinal microbiota and host immunity, and the recent progress and drawbacks of the technology.


Assuntos
Aquicultura , Agentes de Controle Biológico/farmacologia , Microbioma Gastrointestinal/fisiologia , Imunomodulação , Probióticos/farmacologia , Ração Animal/análise , Animais , Bactérias/metabolismo , Fenômenos Fisiológicos Bacterianos , Agentes de Controle Biológico/administração & dosagem , Microbioma Gastrointestinal/efeitos dos fármacos , Nutrientes/análise , Probióticos/administração & dosagem
17.
Int J Mol Sci ; 20(24)2019 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-31817248

RESUMO

Mycotoxins produced by Fusarium species on cereals represent a major concern for food safety worldwide. Fusarium toxins that are currently under regulation for their content in food include trichothecenes, fumonisins, and zearalenone. Biological control of Fusarium spp. has been widely explored with the aim of limiting disease occurrence, but few efforts have focused so far on limiting toxin accumulation in grains. The bacterial genus Streptomyces is responsible for the production of numerous drug molecules and represents a huge resource for the discovery of new molecules. Streptomyces spp. are also efficient plant colonizers and able to employ different mechanisms of control against toxigenic fungi on cereals. This review describes the outcomes of research using Streptomyces strains and/or their derived molecules to limit toxin production and/or contamination of Fusarium species in cereals. Both the scientific and patent literature were analyzed, starting from the year 2000, and we highlight promising results as well as the current pitfalls and limitations of this approach.


Assuntos
Agentes de Controle Biológico/farmacologia , Grão Comestível/microbiologia , Contaminação de Alimentos/prevenção & controle , Fusarium/efeitos dos fármacos , Streptomyces/química , Agentes de Controle Biológico/metabolismo , Bases de Dados Factuais , Fusarium/metabolismo , Micotoxinas/metabolismo , Patentes como Assunto , Streptomyces/metabolismo
18.
BMC Res Notes ; 12(1): 746, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31730018

RESUMO

OBJECTIVE: Rhizoctonia solani is a soil-borne fungal pathogen of many important crop plants. In rice, R. solani causes sheath blight disease, which results in devastating grain yield and quality losses. Few methods are available to control this pathogen and classic single gene resistance mechanisms in rice plants have not been identified. We hypothesize that alternate means of control are available in the environment including free-living amoebae. Amoebae are soil-, water- and air-borne microorganisms that are predominantly heterotrophic. Many amoeba species are mycophagous, and several harm their prey using mechanisms other than phagocytosis. Here, we used light and scanning electron microscopy to survey the interactions of R. solani with four amoeba species, with the goal of identifying amoebae species with potential for biocontrol. RESULTS: We observed a wide range of responses during interactions of R. solani with four different free-living amoebae. Two Acanthamoeba species encyst in co-cultures with R. solani at higher rates than medium without R. solani. Vermamoeba vermiformis (formerly Hartmanella vermiformis) attach to R. solani mycelium and are associated with mycelial shriveling and perforations of fungal cell walls, indicating an antagonistic interaction. No phenotypic changes were observed in co-cultures of Dictyostelium discoideum and R. solani.


Assuntos
Acanthamoeba/fisiologia , Antibiose , Hartmannella/fisiologia , Micélio/ultraestrutura , Controle Biológico de Vetores/métodos , Rhizoctonia/ultraestrutura , Acanthamoeba/microbiologia , Acanthamoeba/ultraestrutura , Agentes de Controle Biológico/metabolismo , Agentes de Controle Biológico/farmacologia , Parede Celular/química , Parede Celular/efeitos dos fármacos , Parede Celular/ultraestrutura , Técnicas de Cocultura , Dictyostelium/microbiologia , Dictyostelium/fisiologia , Dictyostelium/ultraestrutura , Hartmannella/microbiologia , Hartmannella/ultraestrutura , Micélio/efeitos dos fármacos , Micélio/crescimento & desenvolvimento , Micélio/patogenicidade , Oryza/microbiologia , Doenças das Plantas/prevenção & controle , Rhizoctonia/efeitos dos fármacos , Rhizoctonia/crescimento & desenvolvimento , Rhizoctonia/patogenicidade
19.
Appl Microbiol Biotechnol ; 103(23-24): 9287-9303, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31707442

RESUMO

Synthetic chemical pesticides have been used for many years to increase the yield of agricultural crops. However, in the future, this approach is likely to be limited due to negative impacts on human health and the environment. Therefore, studies of the secondary metabolites produced by agriculturally important microorganisms have an important role in improving the quality of the crops entering the human food chain. In this review, we have compiled information about the most important secondary metabolites of fungal species currently used in agriculture pest and disease management.


Assuntos
Anti-Infecciosos/metabolismo , Agentes de Controle Biológico/metabolismo , Produtos Agrícolas/microbiologia , Fungos/metabolismo , Metabolismo Secundário , Agricultura , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Agentes de Controle Biológico/química , Agentes de Controle Biológico/farmacologia , Produtos Agrícolas/efeitos dos fármacos , Produtos Agrícolas/crescimento & desenvolvimento , Fungos/classificação , Controle Biológico de Vetores , Praguicidas/química , Praguicidas/metabolismo , Praguicidas/farmacologia
20.
Int J Mol Sci ; 20(21)2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31671552

RESUMO

Ureases from different biological sources display non-ureolytic properties that contribute to plant defense, in addition to their classical enzymatic urea hydrolysis. Antifungal and entomotoxic effects were demonstrated for Jaburetox, an intrinsically disordered polypeptide derived from jack bean (Canavalia ensiformis) urease. Here we describe the properties of Soyuretox, a polypeptide derived from soybean (Glycine max) ubiquitous urease. Soyuretox was fungitoxic to Candida albicans, leading to the production of reactive oxygen species. Soyuretox further induced aggregation of Rhodnius prolixus hemocytes, indicating an interference on the insect immune response. No relevant toxicity of Soyuretox to zebrafish larvae was observed. These data suggest the presence of antifungal and entomotoxic portions of the amino acid sequences encompassing both Soyuretox and Jaburetox, despite their small sequence identity. Nuclear Magnetic Resonance (NMR) and circular dichroism (CD) spectroscopic data revealed that Soyuretox, in analogy with Jaburetox, possesses an intrinsic and largely disordered nature. Some folding is observed upon interaction of Soyuretox with sodium dodecyl sulfate (SDS) micelles, taken here as models for membranes. This observation suggests the possibility for this protein to modify its secondary structure upon interaction with the cells of the affected organisms, leading to alterations of membrane integrity. Altogether, Soyuretox can be considered a promising biopesticide for use in plant protection.


Assuntos
Agentes de Controle Biológico/farmacologia , Peptídeos/farmacologia , Soja/enzimologia , Urease/química , Animais , Agentes de Controle Biológico/química , Candida albicans/efeitos dos fármacos , Candida albicans/metabolismo , Dicroísmo Circular , Hemócitos/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Simulação de Dinâmica Molecular , Peptídeos/química , Proteínas de Plantas/química , Dobramento de Proteína , Espécies Reativas de Oxigênio/metabolismo , Rhodnius/efeitos dos fármacos
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