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Microbiology Resource Announcements Mar 2023Here, we report complete genome sequences of two clinical isolates of Staphylococcus aureus, namely, Xen31 and Xen36, which have been genetically modified to express an...
Here, we report complete genome sequences of two clinical isolates of Staphylococcus aureus, namely, Xen31 and Xen36, which have been genetically modified to express an optimized Photorhabdus luminescens luciferase operon. Xen31 and Xen36 are bioluminescent strains used widely for investigation of bacterial pathogenesis, drug discovery, and development of novel therapies.
PubMed: 36840571
DOI: 10.1128/mra.00024-23 -
The Journal of Parasitology Jan 2023The entomopathogenic nematode (EPN) Heterorhabditis bacteriophora infects a wide range of insect hosts with the aid of its mutualistic bacteria Photorhabdus luminescens....
The entomopathogenic nematode (EPN) Heterorhabditis bacteriophora infects a wide range of insect hosts with the aid of its mutualistic bacteria Photorhabdus luminescens. While the mutualistic relationship between H. bacteriophora and P. luminescens and the infectivity of the nematode-bacteria complex have been characterized, how nematode fitness is affected by entomopathogenic bacteria existing in association with other EPN species remains poorly understood. In this study, the survival of H. bacteriophora infective juveniles containing or lacking P. luminescens was tested against the entomopathogenic bacteria Xenorhabdus nematophila and Photorhabdus asymbiotica as well as the non-pathogenic Escherichia coli. While X. nematophila and E. coli did not significantly affect the survival of H. bacteriophora, P. asymbiotica exerted a significant effect on nematode survival, particularly on those lacking P. luminescens. These results imply that P. asymbiotica encodes factors that are pathogenic to EPNs. Future efforts will focus on the identification of the bacterial molecular components that induce these effects. This study makes an important contribution to a growing body of research aimed at exploiting the full potential of nematode-bacterial complexes for eliminating noxious insect pests and treating infectious diseases caused by parasitic nematodes.
Topics: Animals; Photorhabdus; Escherichia coli; Nematoda; Symbiosis
PubMed: 36805240
DOI: 10.1645/22-55 -
Fungal Biology 2023Neofusicoccum parvum, is a fungal pathogen and one of the etiological agents of dieback disease in grapevines. The fungus causes deterioration of vines due to vascular...
Neofusicoccum parvum, is a fungal pathogen and one of the etiological agents of dieback disease in grapevines. The fungus causes deterioration of vines due to vascular colonization and/or production of toxins. We report herein the inhibitory effects of Trichoderma spp. isolates and the antifungal effects of cell-free supernatants (CFS) from Xenorhabdus and Photorhabdus bacteria against N. parvum in agar plates. We also evaluated the effects of the most effective fungi and bacteria against the pathogen in pruning wounds of vine shoots. All isolates of Trichoderma exhibited antifungal activity ranging between 82 and 97.5% at 14 days of post-treatment. All Xenorhabdus and Photorhabdus CFS at 10 and 33% concentrations inhibited mycelial growth with X. szentirmaii PAM 11 and PAM 25 causing the highest inhibition (>74%). In the shoot experiments, T. asperellum IB 01/13 and T. asperellum Quality®, X. szentirmaii PAM 11 (undiluted growth culture and CFS) suppressed the fungus by ≥ 93%. Our study highlights the potential of Trichoderma and X. szentirmaii PAM 11 for use as biofungicides in the management of N. parvum in grapevines. Further studies should be conducted to develop formulations of Trichoderma and Xenorhabdus that enhance stability in shelf-life and increase the efficacy of N. parvum control in grapevines under field conditions.
Topics: Trichoderma; Xenorhabdus; Antifungal Agents; Vitis; Plant Diseases; Bacteria
PubMed: 36746558
DOI: 10.1016/j.funbio.2022.12.002 -
Insects Nov 2022The codling moth, (L.) (Lepidoptera: Tortricidae), is one of the major pests in pome fruit production worldwide. Heavy treatment of the larvae of with insecticides...
Identification and Biocontrol Potential of Entomopathogenic Nematodes and Their Endosymbiotic Bacteria in Apple Orchards against the Codling Moth, (L.) (Lepidoptera: Tortricidae).
The codling moth, (L.) (Lepidoptera: Tortricidae), is one of the major pests in pome fruit production worldwide. Heavy treatment of the larvae of with insecticides triggered the development of resistance to many groups of insecticides. In addition, the increasing concern about the adverse effects of synthetic insecticides on human health and the environment has led to the development of sustainable and eco-friendly control practices for . The entomopathogenic nematodes (EPNs) ( and spp.) and their endosymbionts ( and spp.) represent a newly emerging approach to controlling a wide range of insect pests. In the present study, field surveys were conducted in apple orchards to isolate and identify EPNs and their endosymbionts and evaluate their insecticidal efficacy on the larvae of . EPNs were isolated from 12 of 100 soil samples (12%). Seven samples were identified as (Filipjev, 1934) (Rhabditida: Steinernematidae), whereas five samples were assigned to (Poinar, 1976) (Rhabditida: Heterorhabditidae). The pathogenicity of the EPN species/isolates was screened on the last instar larvae of . The two most pathogenic isolates from each EPN species were tested against fifth instar larvae of under controlled conditions. The maximum mortality (100%) was achieved by all EPN species/isolates at a concentration of 100 IJs/larva 96 h after treatment. The endosymbionts of selected and species were identified as subsp. and , respectively. The mortality rates ranged between 25 and 62% when the fifth larval instar larvae of were exposed to the treatment of cell-free supernatants of symbiotic bacteria. In essence, the present survey indicated that EPNs and their symbiotic bacteria have good potential for biological control of .
PubMed: 36554995
DOI: 10.3390/insects13121085 -
Microbial Cell Factories Dec 2022Genetic modifications in Bacillus subtilis have allowed the conversion of myo-inositol into scyllo-inositol, which is proposed as a therapeutic agent for Alzheimer's...
BACKGROUND
Genetic modifications in Bacillus subtilis have allowed the conversion of myo-inositol into scyllo-inositol, which is proposed as a therapeutic agent for Alzheimer's disease. This conversion comprises two reactions catalyzed by two distinct inositol dehydrogenases, IolG and IolW. The IolW-mediated reaction requires the intracellular regeneration of NADPH, and there appears to be a limit to the endogenous supply of NADPH, which may be one of the rate-determining factors for the conversion of inositol. The primary mechanism of NADPH regeneration in this bacterium remains unclear.
RESULTS
The gdh gene of B. subtilis encodes a sporulation-specific glucose dehydrogenase that can use NADP as a cofactor. When gdh was modified to be constitutively expressed, the intracellular NADPH level was elevated, increasing the conversion of inositol. In addition, the bacterial luciferase derived from Photorhabdus luminescens became more luminescent in cells in liquid culture and colonies on culture plates.
CONCLUSION
The results indicated that the luminescence of luciferase was representative of intracellular NADPH levels. Luciferase can therefore be employed to screen for mutations in genes involved in NADPH regeneration in B. subtilis, and artificial manipulation to enhance NADPH regeneration can promote the production of substances such as scyllo-inositol.
Topics: Glucose 1-Dehydrogenase; NADP; Bacillus subtilis; Luminescence; Inositol; Luciferases
PubMed: 36539761
DOI: 10.1186/s12934-022-01993-0 -
ACS Synthetic Biology Jan 2023Rhabdopeptide/xenortide-like peptide (RXP) nonribosomal peptide synthetases (NRPSs) derived from entomophathogenic and bacteria often produce libraries of different...
Rhabdopeptide/xenortide-like peptide (RXP) nonribosomal peptide synthetases (NRPSs) derived from entomophathogenic and bacteria often produce libraries of different peptides varying in amino acid composition, number and degree of methylation, which mainly is a result of promiscuous docking domains (DDs) mediating protein-protein interactions between the different NRPS subunits. In this study, we present two specific RXP-NRPS systems with rather specific DDs that were used as platforms to generate a series of defined RXPs via the exchange of adenylation/methyltransferase (A-MT) domains in the systems followed by heterologous expression in . Additionally, these results suggest that NRPS subunit interaction is not only exclusively dependent on DDs but at least partially also on A domains.
Topics: Peptides; Peptide Synthases; Amino Acids; Escherichia coli
PubMed: 36535068
DOI: 10.1021/acssynbio.2c00472 -
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 -
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 -
BMC Genomics Nov 2022Nematodes are a major group of soil inhabiting organisms. Heterorhabditis nematodes are insect-pathogenic nematodes and live in a close symbiotic association with...
BACKGROUND
Nematodes are a major group of soil inhabiting organisms. Heterorhabditis nematodes are insect-pathogenic nematodes and live in a close symbiotic association with Photorhabdus bacteria. Heterorhabditis-Photorhabdus pair offers a powerful and genetically tractable model to study animal-microbe symbiosis. It is possible to generate symbiont bacteria free (axenic) stages in Heterorhabditis. Here, we compared the transcriptome of symbiotic early-adult stage Heterorhabditis nematodes with axenic early-adult nematodes to determine the nematode genes and pathways involved in symbiosis with Photorhabdus bacteria.
RESULTS
A de-novo reference transcriptome assembly of 95.7 Mb was created for H. bacteriophora by using all the reads. The assembly contained 46,599 transcripts with N50 value of 2,681 bp and the average transcript length was 2,054 bp. The differentially expressed transcripts were identified by mapping reads from symbiotic and axenic nematodes to the reference assembly. A total of 754 differentially expressed transcripts were identified in symbiotic nematodes as compared to the axenic nematodes. The ribosomal pathway was identified as the most affected among the differentially expressed transcripts. Additionally, 12,151 transcripts were unique to symbiotic nematodes. Endocytosis, cAMP signalling and focal adhesion were the top three enriched pathways in symbiotic nematodes, while a large number of transcripts coding for various responses against bacteria, such as bacterial recognition, canonical immune signalling pathways, and antimicrobial effectors could also be identified.
CONCLUSIONS
The symbiotic Heterorhabditis nematodes respond to the presence of symbiotic bacteria by expressing various transcripts involved in a multi-layered immune response which might represent non-systemic and evolved localized responses to maintain mutualistic bacteria at non-threatening levels. Subject to further functional validation of the identified transcripts, our findings suggest that Heterorhabditis nematode immune system plays a critical role in maintenance of symbiosis with Photorhabdus bacteria.
Topics: Animals; Photorhabdus; Rhabditoidea; Symbiosis; Sequence Analysis, RNA; RNA
PubMed: 36344922
DOI: 10.1186/s12864-022-08952-4 -
Acta Crystallographica. Section F,... Nov 2022Type III secretion systems (T3SSs) are proteinaceous devices employed by Gram-negative bacteria to directly transport proteins into a host cell. Substrate recognition...
Type III secretion systems (T3SSs) are proteinaceous devices employed by Gram-negative bacteria to directly transport proteins into a host cell. Substrate recognition and secretion are strictly regulated by the export apparatus of the so-called injectisome. The export gate SctV engages chaperone-bound substrates of the T3SS in its nonameric cytoplasmic domain. Here, the purification and crystallization of the cytoplasmic domains of SctV from Photorhabdus luminescens (LscV) and Aeromonas hydrophila (AscV) are reported. Self-rotation functions revealed that LscV forms oligomers with either eightfold or ninefold symmetry in two different crystal forms. Similarly, AscV was found to exhibit tenfold rotational symmetry. These are the first instances of SctV proteins forming non-nonameric oligomers.
Topics: Type III Secretion Systems; Bacterial Proteins; Crystallography, X-Ray; Molecular Chaperones
PubMed: 36322424
DOI: 10.1107/S2053230X22009736