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Journal of Invertebrate Pathology Oct 2022Toxicity of the metabolites of two bacteria, Photorhabdus luminescens and Xenorhabdus bovienii, symbionts of entomopathogenic nematodes, were tested in the laboratory...
Toxicity of Photorhabdus luminescens and Xenorhabdus bovienii bacterial metabolites to pecan aphids (Hemiptera: Aphididae) and the lady beetle Harmonia axyridis (Coleoptera: Coccinellidae).
Toxicity of the metabolites of two bacteria, Photorhabdus luminescens and Xenorhabdus bovienii, symbionts of entomopathogenic nematodes, were tested in the laboratory against the multicolored Asian lady beetle, Harmonia axyridis, the black pecan aphid, Melanocallis caryaefoliae, and the blackmargined aphid, Monellia caryella. Bacterial broth prepared from both P. luminescens and X. bovienii demonstrated high levels of toxicity equivalent to the pyrethroid insecticide bifenthrin and caused higher insect mortality than tryptic soy broth plus yeast extract (TSY) (blank control) against M. caryella; broth culture of P. luminescens was more effective than TSY against M. caryaefoliae. At the levels tested, the metabolites were not toxic to H. axyridis.
Topics: Animals; Aphids; Carya; Coleoptera; Insecticides; Photorhabdus; Pyrethrins; Xenorhabdus
PubMed: 35944664
DOI: 10.1016/j.jip.2022.107806 -
International Journal of Systematic and... Aug 2018Bacterial symbionts are crucial for the infectivity and success of entomopathogenic nematodes as biological control agents. The current understanding of the symbiotic...
Whole-genome-based revisit of Photorhabdus phylogeny: proposal for the elevation of most Photorhabdus subspecies to the species level and description of one novel species Photorhabdus bodei sp. nov., and one novel subspecies Photorhabdus laumondii subsp. clarkei subsp. nov.
Bacterial symbionts are crucial for the infectivity and success of entomopathogenic nematodes as biological control agents. The current understanding of the symbiotic relationships is limited by taxonomic uncertainties. Here, we used whole-genome sequencing and traditional techniques to reconstruct the phylogenetic relationships between all described Photorhabdus species and subspecies as well as 11 newly isolated symbiotic bacteria of Heterorhabditis nematodes, including the unreported bacterial partner of H. beicherriana. In silico DNA-DNA hybridization, orthologous average nucleotide identity and nucleotide sequence identity of concatenated housekeeping genes scores were calculated and set into relation with current cut-off values for species delimitation in bacteria. Sequence data were complemented with biochemical and chemotaxonomic markers, and ribosomal protein fingerprinting profiles. This polyphasic approach resolves the ambiguous taxonomy of Photorhabdusand lead to the proposal for the elevation of most of them into a higher taxon and the creation of several new taxa: 15 new species, one of which is newly described: Photorhabdus bodei sp. nov. (type strain LJ24-63=DSM 105690=CCOS 1159) and the other 14 arise through the proposal of elevating already described subspecies to species, and are proposed to be renamed as follows: Photorhabdus asymbioticasubsp. australis as Photorhabdus australis sp. nov., Photorhabdus luminescenssubsp. akhurstii as Photorhabdus akhurstii sp. nov., Photorhabdus luminescenssubsp. caribbeanensis as Photorhabdus caribbeanensis sp. nov., Photorhabdus luminescenssubsp. hainanensis as Photorhabdus hainanensis sp. nov., Photorhabdus luminescenssubsp. kayaii as Photorhabdus kayaii sp. nov., Photorhabdus luminescenssubsp. kleinii as Photorhabdus kleinii sp. nov., Photorhabdus luminescenssubsp. namnaonensis as Photorhabdus namnaonensis sp. nov., Photorhabdus luminescenssubsp. noenieputensis as Photorhabdus noenieputensis sp. nov., Photorhabdus luminescenssubsp.laumondii as Photorhabdus laumondii sp. nov., Photorhabdus temperatasubsp. cinerea as Photorhabdus cinerea sp. nov., Photorhabdus temperatasubsp. khanii as Photorhabdus khanii sp. nov., Photorhabdus temperatasubsp. stackebrandtii as Photorhabdus stackebrandtii sp. nov., Photorhabdus temperatasubsp. tasmaniensis as Photorhabdus tasmaniensis sp. nov., and Photorhabdus temperatasubsp. thracensis as Photorhabdus thracensis sp. nov. In addition, we propose the creation of two new subspecies, one of which arises through the reduction of rank: Photorhabdus laumondii subsp. laumondii comb. nov. (basonym: P. luminescenssubsp. laumondii) and the second one is newly described: Photorhabdus laumondii subsp. clarkei subsp. nov. (type strain BOJ-47=DSM 105531=CCOS 1160). Finally, we propose to emend the description of three species, which results from the proposal of elevating three subspecies to the species status: Photorhabdus asymbiotica, Photorhabdus temperata and Photorhabdus luminescens, formerly classified as Photorhabdus asymbioticasubsp. asymbiotica, Photorhabdus temperatasubsp.temperata and Photorhabdus luminescenssubsp. luminescens, respectively.
Topics: Animals; Bacterial Typing Techniques; DNA, Bacterial; Genome, Bacterial; Nucleic Acid Hybridization; Photorhabdus; Phylogeny; Rhabditoidea; Sequence Analysis, DNA; Symbiosis
PubMed: 29877789
DOI: 10.1099/ijsem.0.002820 -
Frontiers in Cellular and Infection... 2014Bacteria communicate via small diffusible molecules to mediate group-coordinated behavior, a process designated as quorum sensing. The basic molecular quorum sensing...
Bacteria communicate via small diffusible molecules to mediate group-coordinated behavior, a process designated as quorum sensing. The basic molecular quorum sensing system of Gram-negative bacteria consists of a LuxI-type autoinducer synthase producing acyl-homoserine lactones (AHLs) as signaling molecules, and a LuxR-type receptor detecting the AHLs to control expression of specific genes. However, many proteobacteria possess one or more unpaired LuxR-type receptors that lack a cognate LuxI-like synthase, referred to as LuxR solos. The enteric and insect pathogenic bacteria of the genus Photorhabdus harbor an extraordinarily high number of LuxR solos, more than any other known bacteria, and all lack a LuxI-like synthase. Here, we focus on the presence and the different types of LuxR solos in the three known Photorhabdus species using bioinformatics analyses. Generally, the N-terminal signal-binding domain (SBD) of LuxR-type receptors sensing AHLs have a motif of six conserved amino acids that is important for binding and specificity of the signaling molecule. However, this motif is altered in the majority of the Photorhabdus-specific LuxR solos, suggesting the use of other signaling molecules than AHLs. Furthermore, all Photorhabdus species contain at least one LuxR solo with an intact AHL-binding motif, which might allow the ability to sense AHLs of other bacteria. Moreover, all three species have high AHL-degrading activity caused by the presence of different AHL-lactonases and AHL-acylases, revealing a high quorum quenching activity against other bacteria. However, the majority of the other LuxR solos in Photorhabdus have a N-terminal so-called PAS4-domain instead of an AHL-binding domain, containing different amino acid motifs than the AHL-sensors, which potentially allows the recognition of a highly variable range of signaling molecules that can be sensed apart from AHLs. These PAS4-LuxR solos are proposed to be involved in host sensing, and therefore in inter-kingdom signaling. Overall, Photorhabdus species are perfect model organisms to study bacterial communication via LuxR solos and their role for a symbiotic and pathogenic life style.
Topics: Acyl-Butyrolactones; Amino Acid Motifs; Carboxylic Ester Hydrolases; Conserved Sequence; Genome, Bacterial; Photorhabdus; Phylogeny; Position-Specific Scoring Matrices; Protein Binding; Protein Interaction Domains and Motifs; Quorum Sensing; Repressor Proteins; Signal Transduction; Trans-Activators
PubMed: 25478328
DOI: 10.3389/fcimb.2014.00166 -
Cellular Microbiology Aug 2021Photorhabdus luminescens Tc toxins are large tripartite ABC-type toxin complexes, composed of TcA, TcB and TcC proteins. Tc toxins are widespread and have shown a...
Photorhabdus luminescens Tc toxins are large tripartite ABC-type toxin complexes, composed of TcA, TcB and TcC proteins. Tc toxins are widespread and have shown a tropism for a variety of targets including insect, mammalian and human cells. However, their receptors and the specific mechanisms of uptake into target cells remain unknown. Here, we show that the TcA protein TcdA1 interacts with N-glycans, particularly Lewis X/Y antigens. This is confirmed using N-acetylglucosamine transferase I (Mgat1 gene product)-deficient Chinese hamster ovary (CHO) Lec1 cells, which are highly resistant to intoxication by the Tc toxin complex most likely due to the absence of complex N-glycans. Restoring Mgat1 gene activity, and hence complex N-glycan biosynthesis, recapitulated the sensitivity of these cells to the toxin. Exogenous addition of Lewis X trisaccharide partially inhibits intoxication in wild-type cells. Additionally, sialic acid also largely reduced binding of the Tc toxin. Moreover, proteolytic activation of TcdA1 alters glycan-binding and uptake into target cells. The data suggest that TcdA1-binding is most likely multivalent, and carbohydrates probably work cooperatively to facilitate binding and intoxication.
Topics: Animals; Bacterial Toxins; CHO Cells; Cricetinae; Cricetulus; Humans; Photorhabdus; Polysaccharides
PubMed: 33720490
DOI: 10.1111/cmi.13326 -
Environmental Microbiology Jan 2017Photorhabdus luminescens maintains a symbiotic relationship with the nematodes Heterorhabditis bacteriophora and together they infect and kill insect larvae. To maintain...
Photorhabdus luminescens maintains a symbiotic relationship with the nematodes Heterorhabditis bacteriophora and together they infect and kill insect larvae. To maintain this symbiotic relationship, the bacteria must produce an array of secondary metabolites to assist in the development and replication of nematodes. The regulatory mechanisms surrounding production of these compounds are mostly unknown. The global post-transcriptional regulator, Hfq, is widespread in bacteria and performs many functions, one of which is the facilitation of sRNA binding to target mRNAs, with recent research thoroughly exploring its various pleiotropic effects. Here we generate and characterize an hfq deletion mutant and show that in the absence of hfq, the bacteria are no longer able to maintain a healthy symbiosis with nematodes due to the abolishment of the production of all known secondary metabolites. RNAseq led us to produce a second deletion of a known repressor, HexA, in the same strain, which restored both metabolite production and symbiosis.
Topics: Animals; Bacterial Proteins; DNA-Binding Proteins; Host Factor 1 Protein; Insecta; Photorhabdus; RNA, Messenger; RNA, Small Untranslated; Rhabditoidea; Secondary Metabolism; Symbiosis
PubMed: 27555343
DOI: 10.1111/1462-2920.13502 -
Microbial Ecology Jan 2021Photorhabdus spp. (Enterobacteriales: Morganellaceae) occur exclusively as symbionts of Heterorhabditis nematodes for which they provide numerous services, including...
Photorhabdus spp. (Enterobacteriales: Morganellaceae) occur exclusively as symbionts of Heterorhabditis nematodes for which they provide numerous services, including killing insects and providing nutrition and defence within the cadavers. Unusually, two species (Photorhabdus cinerea and Photorhabdus temperata) associate with a single population of Heterorhabditis downesi at a dune grassland site. Building on previous work, we investigated competition between these two Photorhabdus species both at the regional (between insects) and local (within insect) level by trait comparison and co-culture experiments. There was no difference between the species with respect to supporting nematode reproduction and protection of cadavers against invertebrate scavengers, but P. cinerea was superior to P. temperata in several traits: faster growth rate, greater antibacterial and antifungal activity and colonisation of a higher proportion of nematodes in co-culture. Moreover, where both bacterial symbionts colonised single nematode infective juveniles, P. cinerea tended to dominate in numbers. Differences between Photorhabdus species were detected in the suite of secondary metabolites produced: P. temperata produced several compounds not produced by P. cinerea including anthraquinone pigments. Bioluminescence emitted by P. temperata also tended to be brighter than that from P. cinerea. Bioluminescence and pigmentation may protect cadavers against scavengers that rely on sight. We conclude that while P. cinerea may show greater local level (within-cadaver) competitive success, co-existence of the two Photorhabdus species in the spatially heterogeneous environment of the dunes is favoured by differing specialisations in defence of the cadaver against differing locally important threats.
Topics: Animals; Anthraquinones; Grassland; Luminescent Measurements; Photorhabdus; Secondary Metabolism; Strongyloidea; Symbiosis
PubMed: 32827089
DOI: 10.1007/s00248-020-01573-y -
Molecular Microbiology Apr 2007Photorhabdus and Xenorhabdus bacteria colonize the intestines of the infective soil-dwelling stage of entomophagous nematodes, Heterorhabditis and Steinernema,... (Review)
Review
Photorhabdus and Xenorhabdus bacteria colonize the intestines of the infective soil-dwelling stage of entomophagous nematodes, Heterorhabditis and Steinernema, respectively. These nematodes infect susceptible insect larvae and release the bacteria into the insect blood. The bacteria kill the insect larvae and convert the cadaver into a food source suitable for nematode growth and development. After several rounds of reproduction the nematodes are recolonized by the bacteria before emerging from the insect cadaver into the soil to search for a new host. Photorhabdus and Xenorhabdus bacteria therefore engage in both pathogenic and mutualistic interactions with different invertebrate hosts as obligate components of their life cycle. In this review we aim to describe current knowledge of the molecular mechanisms utilized by Photorhabdus and Xenorhabdus to control their host-dependent interactions. Recent work has established that there is a trade-off between pathogenicity and mutualism in both these species of bacteria suggesting that the transition between these interactions must be under regulatory control. Despite the superficial similarity between the life cycles of these bacteria, it is now apparent that the molecular components of the regulatory networks controlling pathogenicity and mutualism in Photorhabdus and Xenorhabdus are very different.
Topics: Animals; Nematoda; Photorhabdus; Symbiosis; Xenorhabdus
PubMed: 17493120
DOI: 10.1111/j.1365-2958.2007.05671.x -
Journal of Invertebrate Pathology Feb 2023Photorhabdus spp. and Xenorhabdus spp. bacteria produce a variety of molecules that inhibit bacterial and fungal contamination as well as deter scavenging invertebrates...
Photorhabdus spp. and Xenorhabdus spp. bacteria produce a variety of molecules that inhibit bacterial and fungal contamination as well as deter scavenging invertebrates and some vertebrates in soil. Certain Heterorhabditis/Photorhabdus-infected insect cadavers can be bioluminescent in the dark and/or turn red from the production of anthraquinone pigments. The role of these traits remains unresolved. The aim of the present study was to evaluate the role of red color (anthraquinone) and bioluminescence on the deterrence of insect scavengers. Our data shows that scavenger deterrent factor (SDF) is not related to red cadaver coloration or bioluminescence activity as crickets and ants did not consume Galleria mellonella cadavers infected by P. laumondii strain 48-02 and X. bovienii. Both bacteria exhibit SDF activity but do not produce anthraquinone. Also, the insects were not affected by anthraquinone in agar plugs prepared with supernatant from induced P. laumondii Δpptase Pcep-KM-antA (SVS-275) mutant strain, which overproduces anthraquinone. Since bioluminescence and anthraquinone are not responsible for SDF activity against insect scavengers, more studies are needed to elucidate the SDF compound from Xenorhabdus and Photorhabdus bacteria.
Topics: Animals; Cadaver; Insecta; Moths; Nematoda; Photorhabdus; Symbiosis; Xenorhabdus
PubMed: 36493844
DOI: 10.1016/j.jip.2022.107871 -
Recent Patents on Anti-infective Drug... Jun 2009Phototorhabdus is an insect pathogenic enterobacterium which maintains a mutualistic interaction with heterorhabditid nematodes. While the bacteria live in the nematode... (Review)
Review
Phototorhabdus is an insect pathogenic enterobacterium which maintains a mutualistic interaction with heterorhabditid nematodes. While the bacteria live in the nematode gut, the nematodes live in the soil and infect insect larvae, releasing their symbiotic bacteria into the insect blood. Here the bacteria reproduce and kill the insect by septicaemia. The nematodes then feed on the bacterial biomass and undergo several rounds of reproduction before emerging from the cadaver carrying their bacterial symbionts. Photorhabdus secretes a versatile armory of antimicrobial molecules into the insect corpse. These biocides exert a range of antimicrobial killing activities and serve a dual function. They minimize competition from non-symbiotic bacteria and prevent microbial putrefaction of the nematode-infected insect cadaver. The goal of this review is to describe current knowledge of the molecular mechanisms involved in the production of bacteriocins by Photorhabdus. Recent important advances in identifying novel potent antibiotic compounds from Photorhabdus and elucidating their complex mode of action in relation to pathogenicity and symbiosis associations are also discussed. The last part of this review focuses on the potential role Photorhabdus antibiotics may play in contributing to the discovery of novel pharmaceutical and agrochemical products. The present article is a short review of recent patents on Photohabdus.
Topics: Animals; Anti-Bacterial Agents; Bacteriocins; DNA, Bacterial; Host-Parasite Interactions; Insecta; Models, Biological; Models, Genetic; Nematoda; Photorhabdus; Symbiosis
PubMed: 19519542
DOI: 10.2174/157489109788490280 -
Current Topics in Microbiology and... 2017Various bacterial toxins have potent insecticidal activity. Recently, the Toxin complexes (Tc's) of Photorhabdus and Xenorhabdus species have become an increased focus...
Various bacterial toxins have potent insecticidal activity. Recently, the Toxin complexes (Tc's) of Photorhabdus and Xenorhabdus species have become an increased focus of current research. These large tripartite toxins with molecular masses >1.4 megadaltons consist of three components termed A, B, and C (or TcA, TcB, and TcC). While TcA is involved in receptor binding and toxin translocation, TcC possesses the specific toxin enzyme activity and TcB is a linker between components TcA and TcC. Here, a structure function analysis of the toxins is described and the application of Tc toxins as potential insecticides is discussed.
Topics: Bacterial Toxins; Insecticides; Photorhabdus
PubMed: 28233068
DOI: 10.1007/82_2016_55