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1.
Artigo em Inglês | MEDLINE | ID: mdl-33464198

RESUMO

Three Gram-stain-negative, rod-shaped, non-spore-forming bacteria, BA1T, Q614T and PB68.1T, isolated from the digestive system of Heterorhabditis entomopathogenic nematodes, were biochemically and molecularly characterized to clarify their taxonomic affiliations. The 16S rRNA gene sequences of these strains suggest that they belong to the Gammaproteobacteria, to the family Morganellacea, and to the genus Photorhabdus. Deeper analyses using whole genome-based phylogenetic reconstructions suggest that BA1T is closely related to Photorhabdus akhursti, that Q614T is closely related to Photorhabdus heterorhabditis, and that PB68.1T is closely related to Photorhabdus australis. In silico genomic comparisons confirm these observations: BA1T and P. akhursti 15138T share 68.8 % digital DNA-DNA hybridization (dDDH), Q614T and P. heterorhabditis SF41T share 75.4 % dDDH, and PB68.1T and P. australis DSM 17609T share 76.6  % dDDH. Physiological and biochemical characterizations reveal that these three strains also differ from all validly described Photorhabdus species and from their more closely related taxa, contrary to what was previously suggested. We therefore propose to classify BA1T as a new species within the genus Photorhabdus, Q614T as a new subspecies within P. heterorhabditis, and PB68.1T as a new subspecies within P. australis. Hence, the following names are proposed for these strains: Photorhabdus aegyptia sp. nov. with the type strain BA1T(=DSM 111180T=CCOS 1943T=LMG 31957T), Photorhabdus heterorhabditis subsp. aluminescens subsp. nov. with the type strain Q614T (=DSM 111144T=CCOS 1944T=LMG 31959T) and Photorhabdus australis subsp. thailandensis subsp. nov. with the type strain PB68.1T (=DSM 111145T=CCOS 1942T). These propositions automatically create Photorhabdus heterorhabditis subsp. heterorhabditis subsp. nov. with SF41T as the type strain (currently classified as P. heterorhabditis) and Photorhabdus australis subsp. australis subsp. nov. with DSM17609T as the type strain (currently classified as P. australis).


Assuntos
Nematoides/microbiologia , Photorhabdus/classificação , Filogenia , Animais , Austrália , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Sistema Digestório/microbiologia , Egito , Hibridização de Ácido Nucleico , Photorhabdus/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Tailândia
2.
Mol Genet Genomics ; 296(2): 437-456, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33507381

RESUMO

Wolbachia is an obligate intracellular bacterium that has undergone extensive genomic streamlining in its arthropod and nematode hosts. Because the gene encoding the bacterial DNA recombination/repair protein RecA is not essential in Escherichia coli, abundant expression of this protein in a mosquito cell line persistently infected with Wolbachia strain wStri was unexpected. However, RecA's role in the lytic cycle of bacteriophage lambda provides an explanation for retention of recA in strains known to encode lambda-like WO prophages. To examine DNA recombination/repair capacities in Wolbachia, a systematic examination of RecA and related proteins in complete or nearly complete Wolbachia genomes from supergroups A, B, C, D, E, F, J and S was undertaken. Genes encoding proteins including RecA, RecF, RecO, RecR, RecG and Holliday junction resolvases RuvA, RuvB and RuvC are uniformly absent from Wolbachia in supergroup C and have reduced representation in supergroups D and J, suggesting that recombination and repair activities are compromised in nematode-associated Wolbachia, relative to strains that infect arthropods. An exception is filarial Wolbachia strain wMhie, assigned to supergroup F, which occurs in a nematode host from a poikilothermic lizard. Genes encoding LexA and error-prone polymerases are absent from all Wolbachia genomes, suggesting that the SOS functions induced by RecA-mediated activation of LexA do not occur, despite retention of genes encoding a few proteins that respond to LexA induction in E. coli. Three independent E. coli accessions converge on a single Wolbachia UvrD helicase, which interacts with mismatch repair proteins MutS and MutL, encoded in nearly all Wolbachia genomes. With the exception of MutL, which has been mapped to a eukaryotic association module in Phage WO, proteins involved in recombination/repair are uniformly represented by single protein annotations. Putative phage-encoded MutL proteins are restricted to Wolbachia supergroups A and B and show higher amino acid identity than chromosomally encoded MutL orthologs. This analysis underscores differences between nematode and arthropod-associated Wolbachia and describes aspects of DNA metabolism that potentially impact development of procedures for transformation and genetic manipulation of Wolbachia.


Assuntos
Artrópodes/microbiologia , Reparo do DNA , Nematoides/microbiologia , Recombinases Rec A/genética , Wolbachia/genética , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Especificidade de Hospedeiro , Família Multigênica , Recombinases Rec A/metabolismo , Recombinação Genética , Serina Endopeptidases/genética , Especificidade da Espécie , Wolbachia/classificação , Wolbachia/metabolismo
3.
Fitoterapia ; 148: 104801, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33309650

RESUMO

Three new sesquiterpenoids, peniterpenoids A - C (1-3), together with six known metabolites (4-9) were isolated from an entomogenous fungus Penicillium janthinellum (LB1.20090001) collected from a wheat cyst nematode. The structures of the new compounds were elucidated based on NMR and HRESIMS spectroscopic analyses. The absolute configuration of the C-8 secondary alcohol of peniterpenoid B (2) was determined by [Rh2(OCOCF3)4]-induced ECD experiment. Subsequently, the antimicrobial and DPPH scavenging activities were determined. Compounds 6-8 exhibited moderate antibacterial activities against Staphylococcus aureus (CGMCC1.2465) with MIC values of 25.0, 50.0 and 12.5 µg/mL, respectively.


Assuntos
Antibacterianos/farmacologia , Nematoides/microbiologia , Penicillium/química , Sesquiterpenos/farmacologia , Triticum/parasitologia , Animais , Antibacterianos/isolamento & purificação , China , Testes de Sensibilidade Microbiana , Estrutura Molecular , Sesquiterpenos/isolamento & purificação , Staphylococcus aureus/efeitos dos fármacos
4.
Exp Parasitol ; 218: 108005, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32971132

RESUMO

Nematodiosis are responsible for financial losses in cattle production systems due to treatment costs, falling production rates and animal deaths. The incorporation of sodium alginate pellets containing nematophagous fungi in the bovine diet is a method for the control of nematodiosis. The aims of this study were to evaluate the viability of Arthrobotrys cladodes and Pochonia chlamydosporia contained in sodium alginate pellets after passage through the bovine gastrointestinal tract, as well as to evaluate the effects of single and combined use of these fungi against bovine parasitic nematodes. The reduction in parasitic nematode infective larvae of bovines by the combined use of Arthrobotrys cladodes and Pochonia chlamydosporia was more than the reduction in infective larvae by Arthrobotrys cladodes or Pochonia chlamydosporia alone in the collections 12, 24 and 36 h after giving the pellets to the animals. Arthrobotrys cladodes and Pochonia chlamydosporia combined promoted maximum reduction of infective larvae of 86.3%. Therefore, the combination of Arthrobotrys cladodes and Pochonia chlamydosporia may be an effective method to control gastrointestinal nematodiosis affecting grazing cattle.


Assuntos
Ascomicetos/fisiologia , Doenças dos Bovinos/prevenção & controle , Trato Gastrointestinal/microbiologia , Hypocreales/fisiologia , Infecções por Nematoides/veterinária , Análise de Variância , Animais , Ascomicetos/crescimento & desenvolvimento , Agentes de Controle Biológico , Bovinos , Doenças dos Bovinos/parasitologia , Fezes/parasitologia , Feminino , Trato Gastrointestinal/parasitologia , Hypocreales/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Micélio/crescimento & desenvolvimento , Nematoides/crescimento & desenvolvimento , Nematoides/microbiologia , Infecções por Nematoides/prevenção & controle
5.
PLoS One ; 15(6): e0234129, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32502188

RESUMO

Xenorhabdus and Photorhabdus, symbiotically associated with entomopathogenic nematodes (EPNs), produce a range of antimicrobial compounds. The objective of this study is to identify Xenorhabdus and Photorhabdus and their EPNs hosts, which were isolated from soil samples from Saraburi province, and study their antibacterial activity against 15 strains of drug-resistant bacteria. Fourteen isolates (6.1%), consisting of six Xenorhabdus isolates and eight Photorhabdus isolates, were obtained from 230 soil samples. Based on the BLASTN search incorporating the phylogenetic analysis of a partial recA gene, all six isolates of Xenorhabdus were found to be identical and closely related to X. stockiae. Five isolates of Photorhabdus were found to be identical and closely related to P. luminescens subsp. akhurstii. Two isolates of Photorhabdus were found to be identical and closely related to P. luminescens subsp. hainanensis. The remaining isolate of Photorhabdus was found to be identical to P. asymbiotica subsp. australis. The bacterial extracts from P. luminescens subsp. akhurstii showed strong inhibition the growth of S. aureus strain PB36 (MSRA) by disk diffusion, minimal inhibitory concentration, and minimal bactericidal concentration assay. The combination between each extract from Xenorhabdus/Photorhabdus and oxacillin or vancomycin against S. aureus strain PB36 (MRSA) exhibited no interaction on checkerboard assay. Moreover, killing curve assay of P. luminescens subsp. akhurstii extracts against S. aureus strain PB36 exhibited a steady reduction of 105 CFU/ml to 103 CFU/ml within 30 min. This study demonstrates that Xenorhabdus and Photorhabdus, showed antibacterial activity. This finding may be useful for further research on antibiotic production.


Assuntos
Antibacterianos/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Nematoides/microbiologia , Photorhabdus/metabolismo , Xenorhabdus/metabolismo , Animais , Antibacterianos/isolamento & purificação , Testes de Sensibilidade Microbiana , Oxacilina/farmacologia , Photorhabdus/classificação , Photorhabdus/isolamento & purificação , Filogenia , Solo/parasitologia , Vancomicina/farmacologia , Xenorhabdus/classificação , Xenorhabdus/isolamento & purificação
6.
Int J Syst Evol Microbiol ; 70(4): 2664-2676, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32238230

RESUMO

This study examined over 20 fungal specimens of the Orbiliaceae (Orbiliomycetes) from different regions in China. Our analyses based on morphological traits and the ITS rDNA sequences revealed two new Orbilia species with drechslerella-like asexual morphs. These new species are able to trap nematodes with constricting rings. In addition, Orbilia cf. orientalis is reported as a new cryptic Chinese variant of European collections of O. orientalis. All three species are described and illustrated in detail in this paper. Their phylogenetic relationships with other orbiliaceous species were identified based on their ITS sequences.


Assuntos
Ascomicetos/classificação , Filogenia , Árvores/microbiologia , Animais , Ascomicetos/isolamento & purificação , China , DNA Fúngico/genética , DNA Espaçador Ribossômico/genética , Ácidos Graxos/química , Florestas , Técnicas de Tipagem Micológica , Nematoides/microbiologia , Análise de Sequência de DNA
7.
ISME J ; 14(6): 1494-1507, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32152389

RESUMO

Although the microbiota is known to affect host development, metabolism, and immunity, its impact on host behavior is only beginning to be understood. In order to better characterize behavior modulation by host-associated microorganisms, we investigated how bacteria modulate complex behaviors in the nematode model organism Pristionchus pacificus. This nematode is a predator that feeds on the larvae of other nematodes, including Caenorhabditis elegans. By growing P. pacificus on different bacteria and testing their ability to kill C. elegans, we reveal large differences in killing efficiencies, with a Novosphingobium species showing the strongest enhancement. This enhanced killing was not accompanied by an increase in feeding, which is a phenomenon known as surplus killing, whereby predators kill more prey than necessary for sustenance. Our RNA-seq data demonstrate widespread metabolic rewiring upon exposure to Novosphingobium, which facilitated screening of bacterial mutants with altered transcriptional responses. We identified bacterial production of vitamin B12 as an important cause of such enhanced predatory behavior. Although vitamin B12 is an essential cofactor for detoxification and metabolite biosynthesis, shown previously to accelerate development in C. elegans, supplementation with this enzyme cofactor amplified surplus killing in P. pacificus, whereas mutants in vitamin B12-dependent pathways reduced surplus killing. By demonstrating that production of vitamin B12 by host-associated microbiota can affect complex host behaviors, we reveal new connections between animal diet, microbiota, and nervous system.


Assuntos
Bactérias/metabolismo , Nematoides/fisiologia , Vitamina B 12/metabolismo , Animais , Caenorhabditis elegans/microbiologia , Microbiota , Nematoides/microbiologia , Comportamento Predatório , Vitaminas/metabolismo
8.
Proc Natl Acad Sci U S A ; 117(12): 6762-6770, 2020 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-32161129

RESUMO

Nematode-trapping fungi (NTF) are a group of specialized microbial predators that consume nematodes when food sources are limited. Predation is initiated when conserved nematode ascaroside pheromones are sensed, followed by the development of complex trapping devices. To gain insights into the coevolution of this interkingdom predator-prey relationship, we investigated natural populations of nematodes and NTF that we found to be ubiquitous in soils. Arthrobotrys species were sympatric with various nematode species and behaved as generalist predators. The ability to sense prey among wild isolates of Arthrobotrys oligospora varied greatly, as determined by the number of traps after exposure to Caenorhabditis elegans While some strains were highly sensitive to C. elegans and the nematode pheromone ascarosides, others responded only weakly. Furthermore, strains that were highly sensitive to the nematode prey also developed traps faster. The polymorphic nature of trap formation correlated with competency in prey killing, as well as with the phylogeny of A. oligospora natural strains, calculated after assembly and annotation of the genomes of 20 isolates. A chromosome-level genome assembly and annotation were established for one of the most sensitive wild isolates, and deletion of the only G-protein ß-subunit-encoding gene of A. oligospora nearly abolished trap formation. In summary, our study establishes a highly responsive A. oligospora wild isolate as a model strain for the study of fungus-nematode interactions and demonstrates that trap formation is a fitness character in generalist predators of the nematode-trapping fungus family.


Assuntos
Ascomicetos/genética , Proteínas Fúngicas/genética , Interações Hospedeiro-Patógeno/genética , Modelos Biológicos , Nematoides/microbiologia , Comportamento Predatório , Animais , Ascomicetos/classificação , Ascomicetos/patogenicidade , Genoma Fúngico , Nematoides/genética , Nematoides/metabolismo , Feromônios/metabolismo , Filogenia
9.
Nat Biotechnol ; 38(5): 600-608, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32066956

RESUMO

The western corn rootworm (WCR) decimates maize crops worldwide. One potential way to control this pest is treatment with entomopathogenic nematodes (EPNs) that harbor bacterial symbionts that are pathogenic to insects. However, WCR larvae sequester benzoxazinoid secondary metabolites that are produced by maize and use them to increase their resistance to the nematodes and their symbionts. Here we report that experimental evolution and selection for bacterial symbionts that are resistant to benzoxazinoids improve the ability of a nematode-symbiont pair to kill WCR larvae. We isolated five Photorhabdus symbionts from different nematodes and increased their benzoxazinoid resistance through experimental evolution. Benzoxazinoid resistance evolved through multiple mechanisms, including a mutation in the aquaporin-like channel gene aqpZ. We reintroduced benzoxazinoid-resistant Photorhabdus strains into their original EPN hosts and identified one nematode-symbiont pair that was able to kill benzoxazinoid-sequestering WCR larvae more efficiently. Our results suggest that modification of bacterial symbionts might provide a generalizable strategy to improve biocontrol of agricultural pests.


Assuntos
Aquaporinas/genética , Benzoxazinas/farmacologia , Farmacorresistência Bacteriana , Nematoides/microbiologia , Photorhabdus/fisiologia , Zea mays/crescimento & desenvolvimento , Animais , Proteínas de Bactérias/genética , Evolução Molecular , Engenharia Genética , Mutação , Nematoides/patogenicidade , Controle Biológico de Vetores , Photorhabdus/efeitos dos fármacos , Photorhabdus/genética , Doenças das Plantas/prevenção & controle , Zea mays/parasitologia
10.
Parasitol Res ; 119(1): 123-128, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31735994

RESUMO

Duddingtonia flagrans is a nematode-trapping fungus that has shown promising results as a tool to combat parasitic nematode infections in livestock. The fungus interrupts the parasitic lifecycle by trapping and killing larval stages on pasture to prevent re-infection of animals. One barrier to the fungus' commercial use is scaling up production of the fungus, and specifically of chlamydospores, which survive the digestive tract to grow in fecal pats on pasture, thus have potential as a feed through anthelmintic. The purpose of this study was to evaluate the effect of dehydration on sporulation of the fungus. Disks of Duddingtonia flagrans type strain (ATCC® 13423™) were grown on 17% cornmeal agar for 26 days at 30 °C, then split into three groups; dried quickly at 38 °C and 37% humidity over 48 h ("incubated"), dried more slowly at 24 °C and 55% humidity over 10 days ("air-dried"), or kept at 30 °C and sealed with parafilm to prevent loss of moisture as a control ("wet"). Half of each dried culture was resuspended in water, then heated to liquify and homogenized through vortexing. Spores were then counted in a Neubauer hematocytometer. Both the "air-dried" and "incubated" drying techniques yielded significantly more spores than the "wet" control (Welch's two sample t test p values of .0359 and .0411, respectively). The difference in average chlamydospores per milliliter was insignificant between the two drying techniques, although a visual representation of the data shows less spore count variability in the "air-dried" technique.


Assuntos
Desidratação/fisiopatologia , Duddingtonia/crescimento & desenvolvimento , Nematoides/microbiologia , Infecções por Nematoides/prevenção & controle , Controle Biológico de Vetores/métodos , Esporos Fúngicos/crescimento & desenvolvimento , Animais , Testes Diagnósticos de Rotina , Fezes/microbiologia , Larva/crescimento & desenvolvimento , Nematoides/crescimento & desenvolvimento , Contagem de Ovos de Parasitas
11.
Trends Parasitol ; 36(1): 4-7, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31375436

RESUMO

Xenorhabdus and Photorhabdus species are symbiotic bacteria of the insect-pathogenic soil nematodes that produce insecticidal compounds lethal to prey insects. Recently, there has been much interest in adapting these insecticidals for mosquito control. Here, I advocate the potential of Xenorhabdus/Photorhabdus as natural sources of mosquitocides (larvicides, adulticides) and feeding-deterrents.


Assuntos
Inseticidas/metabolismo , Controle de Mosquitos , Photorhabdus/metabolismo , Xenorhabdus/metabolismo , Animais , Culicidae/microbiologia , Nematoides/microbiologia , Simbiose
12.
Nature ; 576(7787): 459-464, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31747680

RESUMO

The current need for novel antibiotics is especially acute for drug-resistant Gram-negative pathogens1,2. These microorganisms have a highly restrictive permeability barrier, which limits the penetration of most compounds3,4. As a result, the last class of antibiotics that acted against Gram-negative bacteria was developed in the 1960s2. We reason that useful compounds can be found in bacteria that share similar requirements for antibiotics with humans, and focus on Photorhabdus symbionts of entomopathogenic nematode microbiomes. Here we report a new antibiotic that we name darobactin, which was obtained using a screen of Photorhabdus isolates. Darobactin is coded by a silent operon with little production under laboratory conditions, and is ribosomally synthesized. Darobactin has an unusual structure with two fused rings that form post-translationally. The compound is active against important Gram-negative pathogens both in vitro and in animal models of infection. Mutants that are resistant to darobactin map to BamA, an essential chaperone and translocator that folds outer membrane proteins. Our study suggests that bacterial symbionts of animals contain antibiotics that are particularly suitable for development into therapeutics.


Assuntos
Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/patogenicidade , Animais , Antibacterianos/química , Proteínas da Membrana Bacteriana Externa/antagonistas & inibidores , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Linhagem Celular , Modelos Animais de Doenças , Descoberta de Drogas , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Resistência Microbiana a Medicamentos/genética , Proteínas de Escherichia coli/antagonistas & inibidores , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Feminino , Microbioma Gastrointestinal/efeitos dos fármacos , Bactérias Gram-Negativas/genética , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Mutação , Nematoides/microbiologia , Óperon/genética , Photorhabdus/química , Photorhabdus/genética , Photorhabdus/isolamento & purificação , Especificidade por Substrato , Simbiose
13.
J Agric Food Chem ; 67(47): 13061-13072, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31738551

RESUMO

In this study, we purified three new sesquiterpenyl epoxy-cyclohexenoid (SEC) analogues, arthrobotrisin D (11) and its two derivatives, from nematode-trapping fungus Arthrobotrys oligospora. Our results revealed that arthrobotrisin type SEC metabolites could be detected in all the test fungal strains from geographically distinct regions grown on different nutrient media, indicative of unique diagnostic character as chemical indicators for A. oligospora. The time course designs over short-term intervals of the fungus under direct contact and indirect contact with living or dead nematodes revealed that arthrobotrisin B and D (6 and 11) displayed significant relationships (positive or negative correlation) with fungal saprophytic and pathogenic stages during a nematode predation event. Interestingly, fungus on nutrient-limiting medium conducive to fungal trap formation could rapidly drop the concentration levels of arthrobotrisins B and D within 6 h when dead nematodes were around, in great contrast to that for living nematodes. Moreover, only in the fungal strain under direct contact with living dominant soil bacteria, arthrobotrisins B and D exhibited significant increase in amounts. Among them, the new SEC, arthrobotrisin D (11) was found to be a key unique metabolic signal for fungal colony growth and fungal interaction with prey and bacteria. Our study suggested that chemical analysis of SEC metabolites in A. oligospora provides a window into the fungal growth status and much valuable information about ecological environments associated with the nematode infections.


Assuntos
Ascomicetos/química , Compostos de Epóxi/química , Nematoides/microbiologia , Sesquiterpenos/química , Animais , Ascomicetos/crescimento & desenvolvimento , Ascomicetos/metabolismo , Compostos de Epóxi/metabolismo , Estrutura Molecular , Sesquiterpenos/metabolismo
14.
Mol Ecol ; 28(22): 4987-5005, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31618508

RESUMO

Soil nematode communities and food web indices can inform about the complexity, nutrient flows and decomposition pathways of soil food webs, reflecting soil quality. Relative abundance of nematode feeding and life-history groups are used for calculating food web indices, i.e., maturity index (MI), enrichment index (EI), structure index (SI) and channel index (CI). Molecular methods to study nematode communities potentially offer advantages compared to traditional methods in terms of resolution, throughput, cost and time. In spite of such advantages, molecular data have not often been adopted so far to assess the effects of soil management on nematode communities and to calculate these food web indices. Here, we used high-throughput amplicon sequencing to investigate the effects of tillage (conventional vs. reduced) and organic matter addition (low vs. high) on nematode communities and food web indices in 10 European long-term field experiments and we assessed the relationship between nematode communities and soil parameters. We found that nematode communities were more strongly affected by tillage than by organic matter addition. Compared to conventional tillage, reduced tillage increased nematode diversity (23% higher Shannon diversity index), nematode community stability (12% higher MI), structure (24% higher SI), and the fungal decomposition channel (59% higher CI), and also the number of herbivorous nematodes (70% higher). Total and labile organic carbon, available K and microbial parameters explained nematode community structure. Our findings show that nematode communities are sensitive indicators of soil quality and that molecular profiling of nematode communities has the potential to reveal the effects of soil management on soil quality.


Assuntos
Fungos/fisiologia , Nematoides/microbiologia , Nematoides/fisiologia , Animais , Ecossistema , Europa (Continente) , Cadeia Alimentar , Solo , Microbiologia do Solo
15.
PLoS One ; 14(10): e0212655, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31596856

RESUMO

Photorhabdus luminescens is an entomopathogenic bacterium found in symbiosis with the nematode Heterorhabditis. Dam DNA methylation is involved in the pathogenicity of many bacteria, including P. luminescens, whereas studies about the role of bacterial DNA methylation during symbiosis are scarce. The aim of this study was to determine the role of Dam DNA methylation in P. luminescens during the whole bacterial life cycle including during symbiosis with H. bacteriophora. We constructed a strain overexpressing dam by inserting an additional copy of the dam gene under the control of a constitutive promoter in the chromosome of P. luminescens and then achieved association between this recombinant strain and nematodes. The dam overexpressing strain was able to feed the nematode in vitro and in vivo similarly as a control strain, and to re-associate with Infective Juvenile (IJ) stages in the insect. No difference in the amount of emerging IJs from the cadaver was observed between the two strains. Compared to the nematode in symbiosis with the control strain, a significant increase in LT50 was observed during insect infestation with the nematode associated with the dam overexpressing strain. These results suggest that during the life cycle of P. luminescens, Dam is not involved the bacterial symbiosis with the nematode H. bacteriophora, but it contributes to the pathogenicity of the nemato-bacterial complex.


Assuntos
Proteínas de Bactérias/metabolismo , Insetos/microbiologia , Nematoides/microbiologia , Photorhabdus/enzimologia , DNA Metiltransferases Sítio Específica (Adenina-Específica)/metabolismo , Simbiose/fisiologia , Animais
16.
Environ Microbiol ; 21(12): 4648-4661, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31433890

RESUMO

The APSES protein family comprises a conserved class of fungus-specific transcriptional regulators. Some members have been identified in partial ascomycetes. In this study, the APSES protein StuA (AoStuA) of the nematode-trapping fungus Arthrobotrys oligospora was characterized. Compared with the wild-type (WT) strain, three ΔAoStuA mutants grew relatively slowly, displayed a 96% reduction in sporulation capacity and a delay in conidial germination. The reduced sporulation capacity correlated with transcriptional repression of several sporulation-related genes. The mutants were also more sensitive to chemical stressors than the WT strain. Importantly, the mutants were unable to produce mycelial traps for nematode predation. Moreover, peroxisomes and Woronin bodies were abundant in the WT cells but hardly found in the cells of those mutants. The lack of such organelles correlated with transcriptional repression of some genes involved in the biogenesis of peroxisomes and Woronin bodies. The transcript levels of several genes involved in the cAMP/PKA signalling pathway were also significantly reduced in the mutants versus the WT strain, implicating a regulatory role of AoStuA in the transcription of genes involved in the cAMP/PKA signalling pathway that regulates an array of cellular processes and events. In particular, AoStuA is indispensable for A. oligospora trap formation and virulence.


Assuntos
Ascomicetos/metabolismo , Ascomicetos/patogenicidade , Proteínas Fúngicas/metabolismo , Nematoides/microbiologia , Esporos Fúngicos/crescimento & desenvolvimento , Fatores de Transcrição/metabolismo , Animais , Ascomicetos/genética , Ascomicetos/crescimento & desenvolvimento , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Transdução de Sinais , Esporos Fúngicos/genética , Esporos Fúngicos/metabolismo , Fatores de Transcrição/genética , Virulência
17.
BMC Microbiol ; 19(1): 171, 2019 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-31357928

RESUMO

BACKGROUND: Microbiome composition is frequently studied by the amplification and high-throughput sequencing of specific molecular markers (metabarcoding). Various hypervariable regions of the 16S rRNA gene are classically used to estimate bacterial diversity, but other universal bacterial markers with a finer taxonomic resolution could be employed. We compared specificity and sensitivity between a portion of the rpoB gene and the V3 V4 hypervariable region of the 16S rRNA gene. RESULTS: We first designed universal primers for rpoB suitable for use with Illumina sequencing-based technology and constructed a reference rpoB database of 45,000 sequences. The rpoB and V3 V4 markers were amplified and sequenced from (i) a mock community of 19 bacterial strains from both Gram-negative and Gram-positive lineages; (ii) bacterial assemblages associated with entomopathogenic nematodes. In metabarcoding analyses of mock communities with two analytical pipelines (FROGS and DADA2), the estimated diversity captured with the rpoB marker resembled the expected composition of these mock communities more closely than that captured with V3 V4. The rpoB marker had a higher level of taxonomic affiliation, a higher sensitivity (detection of all the species present in the mock communities), and a higher specificity (low rates of spurious OTU detection) than V3 V4. We compared the performance of the rpoB and V3 V4 markers in an animal ecosystem model, the infective juveniles of the entomopathogenic nematode Steinernema glaseri carrying the symbiotic bacteria Xenorhabdus poinarii. Both markers showed the bacterial community associated with this nematode to be of low diversity (< 50 OTUs), but only rpoB reliably detected the symbiotic bacterium X. poinarii. CONCLUSIONS: Our results confirm that different microbiota composition data may be obtained with different markers. We found that rpoB was a highly appropriate marker for assessing the taxonomic structure of mock communities and the nematode microbiota. Further studies on other ecosystems should be considered to evaluate the universal usefulness of the rpoB marker. Our data highlight two crucial elements that should be taken into account to ensure more reliable and accurate descriptions of microbial diversity in high-throughput amplicon sequencing analyses: i) the need to include mock communities as controls; ii) the advantages of using a multigenic approach including at least one housekeeping gene (rpoB is a good candidate) and one variable region of the 16S rRNA gene. This study will be useful to the growing scientific community describing bacterial communities by metabarcoding in diverse ecosystems.


Assuntos
Marcadores Genéticos , Metagenômica/métodos , Microbiota/genética , Nematoides/microbiologia , Animais , Bactérias/classificação , DNA Bacteriano , RNA Polimerases Dirigidas por DNA/genética , Genes Essenciais , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Metagenoma , Filogenia , RNA Ribossômico 16S/genética
18.
Braz J Microbiol ; 50(3): 777-789, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31177380

RESUMO

Nine bacterial strains were previously isolated in association with pinewood nematode (PWN) from wilted pine trees. They proved to be nematicidal in vitro, and one of the highest activities, with potential to control PWN, was showed by Serratia sp. M24T3. Its ecology in association with plants remains unclear. This study aimed to evaluate the ability of strain M24T3 to colonize the internal tissues of the model plant Arabidopsis thaliana using confocal microscopy. Plant growth-promoting bacteria (PGPB) functional traits were tested and retrieved in the genome of strain M24T3. In greenhouse conditions, the bacterial effects of all nematicidal strains were also evaluated, co-inoculated or not with Bradyrhizobium sp. 3267, on Vigna unguiculata fitness. Inoculation of strain M24T3 increased the number of A. thaliana lateral roots and the confocal analysis confirmed effective bacterial colonization in the plant. Strain M24T3 showed cellulolytic activity, siderophores production, phosphate and zinc solubilization ability, and indole acetic acid production independent of supplementation with L-tryptophan. In the genome of strain M24T3, genes involved in the interaction with the plants such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase, chitinolytic activity, and quorum sensing were also detected. The genomic organization showed ACC deaminase and its leucine-responsive transcriptional regulator, and the activity of ACC deaminase was 594.6 nmol α-ketobutyrate µg protein-1 µl-1. Strain M24T3 in co-inoculation with Bradyrhizobium sp. 3267 promoted the growth of V. unguiculata. In conclusion, this study demonstrated the ability of strain M24T3 to colonize other plants besides pine trees as an endophyte and displays PGPB traits that probably increased plant tolerance to stresses.


Assuntos
Arabidopsis/microbiologia , Nematoides/microbiologia , Serratia/fisiologia , Animais , Antibiose , Arabidopsis/crescimento & desenvolvimento , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Carbono-Carbono Liases/genética , Carbono-Carbono Liases/metabolismo , Pinus/parasitologia , Doenças das Plantas/parasitologia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Percepção de Quorum , Serratia/enzimologia , Serratia/genética , Serratia/isolamento & purificação , Vigna/crescimento & desenvolvimento , Vigna/microbiologia
19.
Fungal Biol ; 123(7): 547-554, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31196524

RESUMO

There is well-conserved PacC/Rim101 signaling among ascomycete fungi to mediate environmental pH sensing. For pathogenic fungi, this pathway not only enables fungi to grow over a wide pH range, but it also determines whether these fungi can successfully colonize and invade the targeted host. Within the pal/PacC pathway, palH is a putative ambient pH sensor with a seven-transmembrane domain. To characterize the function of a palH homolog, AopalH, in the nematophagous fungus Arthrobotrys oligospora, we knocked out the encoding gene of AopalH through homologous recombination, and the transformants exhibited slower growth rates, greater sensitivities to cationic and hyperoxidation stresses, as well as reduced conidiation and reduced trap formation, suggesting that the pH regulatory system has critical functions in nematophagous fungi. Our results provide novel insights into the mechanisms of pH response and regulation in fungi.


Assuntos
Ascomicetos/fisiologia , Ascomicetos/patogenicidade , Proteínas Fúngicas/metabolismo , Nematoides/microbiologia , Animais , Ascomicetos/genética , Ascomicetos/crescimento & desenvolvimento , Proteínas Fúngicas/genética , Técnicas de Inativação de Genes , Concentração de Íons de Hidrogênio , Hifas/crescimento & desenvolvimento , Mutação , Transdução de Sinais , Esporos Fúngicos/genética , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/patogenicidade , Esporos Fúngicos/fisiologia , Estresse Fisiológico , Virulência/genética
20.
Parasitology ; 146(10): 1347-1351, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31148530

RESUMO

Nematophagous fungi are used in the biological control of the parasitic helminths of animals and plants. The association of ovicidal and predator nematophagous fungi may present a complementary and increased action on the biological control of helminths. Joint growth compatibility and predation tests were carried out on infective larvae of nematode parasites of bovines with the nematophagous fungus ovicide Pochonia chlamydosporia and the nematophagous fungus predator Arthrobotrys cladodes. The tests of antagonism in direct confrontation, antibiosis and the effect of volatile metabolites between the isolates of P. chlamydosporia and A. cladodes indicated the viability of joint growth of these fungi. The association of the fungi P. chlamydosporia and A. cladodes presented a higher predatory capacity of infective larvae of the parasitic nematodes of bovines when compared to the predation of the fungi used alone. Therefore, under laboratory conditions, the fungi studied presented growth compatibility and the association of these increased the nematicidal activity against parasitic helminths of cattle.


Assuntos
Antibiose , Ascomicetos/crescimento & desenvolvimento , Doenças dos Bovinos/prevenção & controle , Nematoides/crescimento & desenvolvimento , Infecções por Nematoides/veterinária , Controle Biológico de Vetores/métodos , Animais , Ascomicetos/patogenicidade , Bovinos , Larva/crescimento & desenvolvimento , Larva/microbiologia , Nematoides/microbiologia , Infecções por Nematoides/prevenção & controle
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