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Journal of Invertebrate Pathology Jun 2023Locusts occasionally represent a danger in Africa despite intensive management measures, leading to severe yield loss and a commensurate loss of food and money. The...
Biochemical compositions and histopathology of the young and aged nymphs of the desert locust Schistocerca gregaria Forsskål (Orthoptera: Acrididae) affected by Photorhabdus luminescens (Enterobacterales: Morganellaceae).
Locusts occasionally represent a danger in Africa despite intensive management measures, leading to severe yield loss and a commensurate loss of food and money. The laboratory assessment of the toxicity of the Photorhabdus luminescens bacteria and its cell-free filtrate used Schistocerca gregaria nymphs in the second and fifth nymphs as test insects. Greater mortality was seen in locust nymphs of the second and fifth instars due to the high levels of toxicity produced by the bacterial suspension and its cell-free filtrate. The amounts of protein, fat, and carbohydrates in the treated locusts were drastically reduced. For the treated second and fifth instar nymphs of the desert locust, adverse effects on the muscular layers of the midgut and the muscles in the jumping legs were investigated.
Topics: Animals; Grasshoppers; Photorhabdus; Insecta
PubMed: 37068730
DOI: 10.1016/j.jip.2023.107922 -
Insects Aug 2020This special issue contains articles that add to the ever-expanding toolbox of insect pathogenic nematodes (entomopathogenic nematodes; EPNs) as well articles that...
This special issue contains articles that add to the ever-expanding toolbox of insect pathogenic nematodes (entomopathogenic nematodes; EPNs) as well articles that provide new insights into the mutualistic interaction between EPNs and their hosts. The study of natural infection models such as EPNs allows detailed insight into micro- and macro-evolutionary dynamics of innate immune reactions, including known but also emerging branches of innate immunity. Additional new insights into the kinetics of EPN infections are gained by increased spatiotemporal resolution of advanced transcriptome studies and live imaging.
PubMed: 32872298
DOI: 10.3390/insects11090577 -
Trends in Parasitology Jan 2020Xenorhabdus and Photorhabdus species are symbiotic bacteria of the insect-pathogenic soil nematodes that produce insecticidal compounds lethal to prey insects. Recently,... (Review)
Review
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.
Topics: Animals; Culicidae; Insecticides; Mosquito Control; Nematoda; Photorhabdus; Symbiosis; Xenorhabdus
PubMed: 31375436
DOI: 10.1016/j.pt.2019.07.003 -
Nature Microbiology Oct 2022Discovery of antibiotics acting against Gram-negative species is uniquely challenging due to their restrictive penetration barrier. BamA, which inserts proteins into the...
Discovery of antibiotics acting against Gram-negative species is uniquely challenging due to their restrictive penetration barrier. BamA, which inserts proteins into the outer membrane, is an attractive target due to its surface location. Darobactins produced by Photorhabdus, a nematode gut microbiome symbiont, target BamA. We reasoned that a computational search for genes only distantly related to the darobactin operon may lead to novel compounds. Following this clue, we identified dynobactin A, a novel peptide antibiotic from Photorhabdus australis containing two unlinked rings. Dynobactin is structurally unrelated to darobactins, but also targets BamA. Based on a BamA-dynobactin co-crystal structure and a BAM-complex-dynobactin cryo-EM structure, we show that dynobactin binds to the BamA lateral gate, uniquely protruding into its β-barrel lumen. Dynobactin showed efficacy in a mouse systemic Escherichia coli infection. This study demonstrates the utility of computational approaches to antibiotic discovery and suggests that dynobactin is a promising lead for drug development.
Topics: Animals; Anti-Bacterial Agents; Bacterial Outer Membrane Proteins; Escherichia coli; Escherichia coli Proteins; Gram-Negative Bacteria; Mice; Peptides; Phenylpropionates
PubMed: 36163500
DOI: 10.1038/s41564-022-01227-4 -
Experimental Parasitology Sep 2019Only two drugs are currently available for the treatment of Chagas disease and their effectiveness are unsatisfactory. Photorhabdus luminescens and Xenorhabdus...
Only two drugs are currently available for the treatment of Chagas disease and their effectiveness are unsatisfactory. Photorhabdus luminescens and Xenorhabdus nematophila, two enteric bacteria highly pathogenic to a broad range of insects, have been studied as potential source for bioactive metabolites against protozoa causing neglected tropical diseases. Therefore, we tested the in vitro anti-Trypanosoma cruzi activity of secreted metabolites from these bacteria. The conditioned medium of X. nematophila and P. luminescens showed significant parasiticidal activity in a concentration-dependent manner (ICXN = 0.34 mg/mL, ICPL = 1.0 mg/mL). The parasiticidal compound was identified as a small molecule stable to heating and pH changes ranging from 2 to 12. Moreover, anti-Trypanosoma molecules secreted by both bacteria stimulate the trypanocidal activity of macrophages by a mechanism independent of nitric oxide. Summarizing, our studies reveal that P. luminescens and X. nematophila are potential sources of putative novel drugs against Chagas disease.
Topics: Analysis of Variance; Animals; Bacterial Proteins; Biological Assay; Chagas Disease; Culture Media, Conditioned; Endopeptidase K; Humans; Hydrogen-Ion Concentration; Inhibitory Concentration 50; Photorhabdus; Temperature; Trypanocidal Agents; Trypanosoma cruzi; Xenorhabdus
PubMed: 31279930
DOI: 10.1016/j.exppara.2019.107724 -
International Journal of Molecular... Jun 2022Due to its essential role in cellular processes, actin is a common target for bacterial toxins. One such toxin, TccC3, is an effector domain of the ABC-toxin produced by...
Due to its essential role in cellular processes, actin is a common target for bacterial toxins. One such toxin, TccC3, is an effector domain of the ABC-toxin produced by entomopathogenic bacteria of spp. Unlike other actin-targeting toxins, TccC3 uniquely ADP-ribosylates actin at Thr-148, resulting in the formation of actin aggregates and inhibition of phagocytosis. It has been shown that the fully modified F-actin is resistant to depolymerization by cofilin and gelsolin, but their effects on partially modified actin were not explored. We found that only F-actin unprotected by tropomyosin is the physiological TccC3 substrate. Yet, ADP-ribosylated G-actin can be produced upon cofilin-accelerated F-actin depolymerization, which was only mildly inhibited in partially modified actin. The affinity of TccC3-ADP-ribosylated G-actin for profilin and thymosin-β4 was weakened moderately but sufficiently to potentiate spontaneous polymerization in their presence. Interestingly, the Arp2/3-mediated nucleation was also potentiated by T148-ADP-ribosylation. Notably, even partially modified actin showed reduced bundling by plastins and α-actinin. In agreement with the role of these and other tandem calponin-homology domain actin organizers in the assembly of the cortical actin network, TccC3 induced intense membrane blebbing in cultured cells. Overall, our data suggest that TccC3 imposes a complex action on the cytoskeleton by affecting F-actin nucleation, recycling, and interaction with actin-binding proteins involved in the integration of actin filaments with each other and cellular elements.
Topics: ADP Ribose Transferases; Actin Cytoskeleton; Actin Depolymerizing Factors; Actins; Adenosine Diphosphate; Photorhabdus
PubMed: 35806028
DOI: 10.3390/ijms23137026 -
International Journal of Systematic and... Jan 2021Three Gram-stain-negative, rod-shaped, non-spore-forming bacteria, BA1, Q614 and PB68.1, isolated from the digestive system of entomopathogenic nematodes, were...
Three Gram-stain-negative, rod-shaped, non-spore-forming bacteria, BA1, Q614 and PB68.1, isolated from the digestive system of 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 , and to the genus . Deeper analyses using whole genome-based phylogenetic reconstructions suggest that BA1 is closely related to , that Q614 is closely related to and that PB68.1 is closely related to genomic comparisons confirm these observations: BA1 and 15138 share 68.8 % digital DNA-DNA hybridization (dDDH), Q614 and SF41 share 75.4 % dDDH, and PB68.1 and DSM 17609 share 76.6 % dDDH. Physiological and biochemical characterizations reveal that these three strains also differ from all validly described species and from their more closely related taxa, contrary to what was previously suggested. We therefore propose to classify BA1 as a new species within the genus , Q614 as a new subspecies within and PB68.1 as a new subspecies within . Hence, the following names are proposed for these strains: sp. nov. with the type strain BA1(=DSM 111180=CCOS 1943=LMG 31957), subsp subsp. nov. with the type strain Q614 (=DSM 111144=CCOS 1944=LMG 31959) and subsp subsp. nov. with the type strain PB68.1 (=DSM 111145=CCOS 1942). These propositions automatically create subsp subsp. nov. with SF41 as the type strain (currently classified as ) and subsp. subsp. nov. with DSM17609 as the type strain (currently classified as ).
Topics: Animals; Australia; Bacterial Typing Techniques; Base Composition; DNA, Bacterial; Digestive System; Egypt; Nematoda; Nucleic Acid Hybridization; Photorhabdus; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Thailand
PubMed: 33464198
DOI: 10.1099/ijsem.0.004610 -
Frontiers in Insect Science 2023The term "microbial control" has been used to describe the use of microbial pathogens (bacteria, viruses, or fungi) or entomopathogenic nematodes (EPNs) to control... (Review)
Review
The term "microbial control" has been used to describe the use of microbial pathogens (bacteria, viruses, or fungi) or entomopathogenic nematodes (EPNs) to control various insect pest populations. EPNs are among the best biocontrol agents, and major developments in their use have occurred in recent decades, with many surveys having been conducted all over the world to identify EPNs that may have potential in the management of insect pests. For nematodes, the term "entomopathogenic" means "causing disease to insects" and is mainly used in reference to the bacterial symbionts of and ( and , respectively), which cause EPN infectivity. A compendium of our multiannual experiences on EPN surveys and on their collection, identification, characterization, and use in agro-forestry ecosystems is presented here to testify and demonstrate once again that biological control with EPNs is possible and offers many advantages over chemicals, such as end-user safety, minimal damage to natural enemies, and lack of environmental pollution, which are essential conditions for an advanced IPM strategy.
PubMed: 38469514
DOI: 10.3389/finsc.2023.1195254 -
Biology Nov 2022Entomopathogenic nematodes (EPNs) are insect parasitic nematodes of the genera and . These nematodes are symbiotically associated with the bacteria, and respectively....
Entomopathogenic nematodes (EPNs) are insect parasitic nematodes of the genera and . These nematodes are symbiotically associated with the bacteria, and respectively. National parks in Thailand are a potentially rich resource for recovering native EPNs and their symbiotic bacteria. The objectives of this study are to isolate and identify EPNs and their bacterial flora from soil samples in four national parks in Thailand and to evaluate their efficacy for controlling mosquito larvae. Using a baiting method with a moth larvae and a White trap technique, 80 out of 840 soil samples (9.5%) from 168 field sites were positive for EPNs. Sequencing of an internal transcribed spacer resulted in the molecular identification of nematode isolates as , and SGmg3, while using 28S rDNA sequencing, nematode species were identified as , , , and one closely related to . For the symbiotic bacterial isolates, based on sequencing, the spp. were identified as subsp. , subsp. and subsp. . isolates were identified as , , , and . Results of bioassays demonstrate that isolates were effective on both and . Therefore, we conclude that soil from Thailand's national parks contain a high diversity of entomopathogenic nematodes and their symbiotic bacteria. bacteria are larvicidal against culicine mosquitoes and may serve as effective biocontrol agents.
PubMed: 36421372
DOI: 10.3390/biology11111658 -
Parasites & Vectors Jul 2020The control of insects of medical importance, such as Aedes aegypti and Aedes albopictus are still the only effective way to prevent the transmission of diseases, such... (Review)
Review
The control of insects of medical importance, such as Aedes aegypti and Aedes albopictus are still the only effective way to prevent the transmission of diseases, such as dengue, chikungunya and Zika. Their control is performed mainly using chemical products; however, they often have low specificity to non-target organisms, including humans. Also, studies have reported resistance to the most commonly used insecticides, such as the organophosphate and pyrethroids. Biological control is an ecological and sustainable method since it has a slow rate of insect resistance development. Bacterial species of the genera Xenorhabdus and Photorhabdus have been the target of several research groups worldwide, aiming at their use in agricultural, pharmaceutical and industrial products. This review highlights articles referring to the use of Xenorhabdus and Photorhabdus for insects and especially for mosquito control proposing future ways for their biotechnological applicability. Approximately 24 species of Xenorhabdus and five species of Photorhabdus have been described to have insecticidal properties. These studies have shown genes that are capable of encoding low molecular weight proteins, secondary toxin complexes and metabolites with insecticide activities, as well as antibiotic, fungicidal and antiparasitic molecules. In addition, several species of Xenorhabdus and Photorhabdus showed insecticidal properties against mosquitoes. Therefore, these biological agents can be used in new control methods, and must be, urgently considered in short term, in studies and applications, especially in mosquito control.
Topics: Aedes; Animals; Bacterial Toxins; Chikungunya Fever; Dengue; Genes, Bacterial; Insecta; Insecticides; Larva; Mosquito Control; Mosquito Vectors; Pest Control, Biological; Photorhabdus; Vector Borne Diseases; Xenorhabdus; Zika Virus Infection
PubMed: 32727530
DOI: 10.1186/s13071-020-04236-6