Analyses of Xenorhabdus griffiniae genomes reveal two distinct sub-species that display intra-species variation due to prophages.

Background: Nematodes of the genus Steinernema and their Xenorhabdus bacterial symbionts are lethal entomopathogens that are useful in the biocontrol of insect pests, as sources of diverse natural products, and as research models for mutualism and parasitism. Xenorhabdus play a central role in all aspects of the Steinernema lifecycle, and a deeper understanding of their genomes therefore has the potential to spur advances in each of these applications.

Results: Here, we report a comparative genomics analysis of Xenorhabdus griffiniae, including the symbiont of Steinernema hermaphroditum nematodes, for which genetic and genomic tools are being developed.

The LrhA transcriptional regulator modulates production of γ-keto--acyl amides with inhibitory activity against mutualistic host nematode egg hatching.

Unlabelled: is a symbiotic Gammaproteobacterium that produces diverse natural products that facilitate mutualistic and pathogenic interactions in their nematode and insect hosts, respectively. The interplay between secondary metabolism and symbiosis stage is tuned by various global regulators. An example of such a regulator is the LysR-type protein transcription factor LrhA, which regulates amino acid metabolism and is necessary for virulence in insects and normal nematode progeny production.

Bacterial hemophilin homologs and their specific type eleven secretor proteins have conserved roles in heme capture and are diversifying as a family.

Cellular life relies on enzymes that require metals, which must be acquired from extracellular sources. Bacteria utilize surface and secreted proteins to acquire such valuable nutrients from their environment. These include the cargo proteins of the type eleven secretion system (T11SS), which have been connected to host specificity, metal homeostasis, and nutritional immunity evasion.

Green and red fluorescent strains of HGB2511, the bacterial symbiont of the nematode (India).

entomopathogenic nematodes form specific, obligate symbiotic associations with gram-negative, gammaproteobacteria members of the genus. Together, the nematodes and symbiotic bacteria infect and kill insects, utilize the nutrient-rich cadaver for reproduction, and then reassociate, the bacteria colonizing the nematodes' anterior intestines before the nematodes leave the cadaver to search for new prey. In addition to their use in biocontrol of insect pests, these nematode-bacteria pairs are highly tractable experimental laboratory models for animal-microbe symbiosis and parasitism research.

Conjugation and transposon mutagenesis of HGB2511, the bacterial symbiont of the nematode (India).

Symbiosis, the beneficial interactions between two organisms, is a ubiquitous feature of all life on Earth, including associations between animals and bacteria. However, the specific molecular and cellular mechanisms which underlie the diverse partnerships formed between animals and bacteria are still being explored. Entomopathogenic nematodes transport bacteria between insect hosts, together they kill the insect, and the bacteria consume the insect and serve as food source for the nematodes.

Breaking Barriers with Bread: Using the Sourdough Starter Microbiome to Teach High-Throughput Sequencing Techniques.

Widespread usage of high-throughput sequencing (HTS) in the LIFE SCIENCES has produced a demand for undergraduate and graduate institutions to offer classes exposing students to all aspects of HTS (sample acquisition, laboratory work, sequencing technologies, bioinformatics, and statistical analyses). Despite the increase in demand, many challenges exist for these types of classes. We advocate for the usage of the sourdough starter microbiome for implementing meta-amplicon sequencing.

A Surface Exposed, Two-Domain Lipoprotein Cargo of a Type XI Secretion System Promotes Colonization of Host Intestinal Epithelia Expressing Glycans.

The only known required component of the newly described Type XI secretion system (TXISS) is an outer membrane protein (OMP) of the DUF560 family. TXISS are broadly distributed across proteobacteria, but properties of the cargo proteins they secrete are largely unexplored. We report biophysical, histochemical, and phenotypic evidence that NilC is surface exposed.

Apex Predator Nematodes and Meso-Predator Bacteria Consume Their Basal Insect Prey through Discrete Stages of Chemical Transformations.

Microbial symbiosis drives physiological processes of higher-order systems, including the acquisition and consumption of nutrients that support symbiotic partner reproduction. Metabolic analytics provide new avenues to examine how chemical ecology, or the conversion of existing biomass to new forms, changes over a symbiotic life cycle. We applied these approaches to the nematode Steinernema carpocapsae, its mutualist bacterium, Xenorhabdus nematophila, and the insects they infect.

A Widespread Bacterial Secretion System with Diverse Substrates.

In host-associated bacteria, surface and secreted proteins mediate acquisition of nutrients, interactions with host cells, and specificity of tissue localization. In Gram-negative bacteria, the mechanism by which many proteins cross and/or become tethered to the outer membrane remains unclear. The domain of unknown function 560 (DUF560) occurs in outer membrane proteins throughout and has been implicated in host-bacterium interactions and lipoprotein surface exposure.

Interactions of host-associated multispecies bacterial communities.

The oral microbiome comprises microbial communities colonizing biotic (epithelia, mucosa) and abiotic (enamel) surfaces. Different communities are associated with health (eg, immune development, pathogen resistance) and disease (eg, tooth loss and periodontal disease). Like any other host-associated microbiome, colonization and persistence of both beneficial and dysbiotic oral microbiomes are dictated by successful utilization of available nutrients and defense against host and competitor assaults.

Xenorhabdus nematophila bacteria shift from mutualistic to virulent Lrp-dependent phenotypes within the receptacles of Steinernema carpocapsae insect-infective stage nematodes.

Xenorhabdus nematophila bacteria are mutualists of Steinernema carpocapsae nematodes and pathogens of insects. Xenorhabdus nematophila exhibits phenotypic variation between insect virulence (V) and the mutualistic (M) support of nematode reproduction and colonization initiation in the infective juvenile (IJ) stage nematode that carries X. nematophila between insect hosts.

Symbiont-mediated competition: Xenorhabdus bovienii confer an advantage to their nematode host Steinernema affine by killing competitor Steinernema feltiae.

Bacterial symbionts can affect several biotic interactions of their hosts, including their competition with other species. Nematodes in the genus Steinernema utilize Xenorhabdus bacterial symbionts for insect host killing and nutritional bioconversion. Here, we establish that the Xenorhabdus bovienii bacterial symbiont (Xb-Sa-78) of Steinernema affine nematodes can impact competition between S.

Studying the Symbiotic Bacterium in Individual, Living Nematodes Using Microfluidic Systems.

Animal-microbe symbioses are ubiquitous in nature and scientifically important in diverse areas, including ecology, medicine, and agriculture. nematodes and bacteria compose an established, successful model system for investigating microbial pathogenesis and mutualism. The bacterium is a species-specific mutualist of insect-infecting nematodes.

The insect pathogenic bacterium Xenorhabdus innexi has attenuated virulence in multiple insect model hosts yet encodes a potent mosquitocidal toxin.

Background: Xenorhabdus innexi is a bacterial symbiont of Steinernema scapterisci nematodes, which is a cricket-specialist parasite and together the nematode and bacteria infect and kill crickets. Curiously, X. innexi expresses a potent extracellular mosquitocidal toxin activity in culture supernatants.

Ready or Not: Microbial Adaptive Responses in Dynamic Symbiosis Environments.

In mutually beneficial and pathogenic symbiotic associations, microbes must adapt to the host environment for optimal fitness. Both within an individual host and during transmission between hosts, microbes are exposed to temporal and spatial variation in environmental conditions. The phenomenon of phenotypic variation, in which different subpopulations of cells express distinctive and potentially adaptive characteristics, can contribute to microbial adaptation to a lifestyle that includes rapidly changing environments.

The Global Transcription Factor Lrp Is both Essential for and Inhibitory to Xenorhabdus nematophila Insecticidal Activity.

In the entomopathogenic bacterium , cell-to-cell variation in the abundance of the Lrp transcription factor leads to virulence modulation; low Lrp levels are associated with a virulent phenotype and suppression of antimicrobial peptides (AMPs) in insects, while cells that lack or express high Lrp levels are virulence attenuated and elicit AMP expression. To better understand the basis of these phenotypes, we examined strains expressing fixed Lrp levels. Unlike the -null mutant, the high- strain is fully virulent in , suggesting that these two strains have distinct underlying causes of virulence attenuation in Indeed, the -null mutant was defective in cytotoxicity against hemocytes relative to that in the high- and low- strains.

High Levels of the Xenorhabdus nematophila Transcription Factor Lrp Promote Mutualism with the Steinernema carpocapsae Nematode Host.

bacteria are mutualistic symbionts of nematodes and pathogens of insects. The global regulator Lrp controls the expression of many genes involved in both mutualism and pathogenic activities, suggesting a role in the transition between the two host organisms. We previously reported that natural populations of exhibit various levels of Lrp expression and that cells expressing relatively low levels of Lrp are optimized for virulence in the insect The adaptive advantage of the high-Lrp-expressing state was not established.

The Global Regulators Lrp, LeuO, and HexA Control Secondary Metabolism in Entomopathogenic Bacteria.

TTO1 and HGB081 are insect pathogenic bacteria and producers of various structurally diverse bioactive natural products. In these entomopathogenic bacteria we investigated the role of the global regulators Lrp, LeuO, and HexA in the production of natural products. Lrp is a general activator of natural product biosynthesis in and for most compounds in TTO1.

R-type bacteriocins in related strains of Xenorhabdus bovienii: Xenorhabdicin tail fiber modularity and contribution to competitiveness.

R-type bacteriocins are contractile phage tail-like structures that are bactericidal towards related bacterial species. The C-terminal region of the phage tail fiber protein determines target-binding specificity. The mutualistic bacteria Xenorhabdus nematophila and X.

Are you my symbiont? Microbial polymorphic toxins and antimicrobial compounds as honest signals of beneficial symbiotic defensive traits.

In defensive symbioses where microbes benefit their host by killing competitors, predators or parasites, natural selection should favor the transmission of microbes with the most beneficial defensive traits. During the initiation of symbiosis, the host's ability to accurately pre-assess a symbiont's beneficial traits would be a selective advantage. We propose that one mechanism by which a host could recognize and select a beneficial partner would be if the latter displayed an honest signal of its defensive or other symbiotic capabilities.

Nematode-bacteria mutualism: Selection within the mutualism supersedes selection outside of the mutualism.

The coevolution of interacting species can lead to codependent mutualists. Little is known about the effect of selection on partners within verses apart from the association. Here, we determined the effect of selection on bacteria (Xenorhabdus nematophila) both within and apart from its mutualistic partner (a nematode, Steinernema carpocapsae).

Comparison of Xenorhabdus bovienii bacterial strain genomes reveals diversity in symbiotic functions.

Background: Xenorhabdus bacteria engage in a beneficial symbiosis with Steinernema nematodes, in part by providing activities that help kill and degrade insect hosts for nutrition. Xenorhabdus strains (members of a single species) can display wide variation in host-interaction phenotypes and genetic potential indicating that strains may differ in their encoded symbiosis factors, including secreted metabolites.

Methods: To discern strain-level variation among symbiosis factors, and facilitate the identification of novel compounds, we performed a comparative analysis of the genomes of 10 Xenorhabdus bovienii bacterial strains.

Comparative genomics of Steinernema reveals deeply conserved gene regulatory networks.

Background: Parasitism is a major ecological niche for a variety of nematodes. Multiple nematode lineages have specialized as pathogens, including deadly parasites of insects that are used in biological control. We have sequenced and analyzed the draft genomes and transcriptomes of the entomopathogenic nematode Steinernema carpocapsae and four congeners (S.

The Global Transcription Factor Lrp Controls Virulence Modulation in Xenorhabdus nematophila.

Unlabelled: The bacterium Xenorhabdus nematophila engages in phenotypic variation with respect to pathogenicity against insect larvae, yielding both virulent and attenuated subpopulations of cells from an isogenic culture. The global regulatory protein Lrp is necessary for X. nematophila virulence and immunosuppression in insects, as well as colonization of the mutualistic host nematode Steinernema carpocapsae, and mediates expression of numerous genes implicated in each of these phenotypes.