Physiological Constants of the Entomopathogenic Bacterium <i>Xenorhabdus nematophila</i> Determined by Microbial Growth Kinetics

Kooliyottil, Rinu; Inman, Floyd L.; Mandjiny, Sivanadane; Holmes, Len

doi:10.1155/2014/834054

Cited by 3 publications

(2 citation statements)

References 10 publications

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“…An alternative approach to establishing the relative importance of top-down immune regulation and bottom-up resource utilization is to remove the effects of the host immune response by quantifying in vitro parasite growth dynamics. Although previous studies have compared the effects of different nutrients on in vitro microbial growth, these usually involve batch cultures with generic media containing multiple nutrients that are simultaneously varied or the modification of a single dietary component (Bowen et al, 2012; Kooliyottil et al, 2014; Pulkkinen et al, 2018). In contrast, in the present study we systematically varied key nutrients in twenty solutions that mimicked, as far as possible, the nutritional conditions that the bacterium could expect to face within its host following different dietary regimes (Holdbrook, Andongma, et al, 2024).…”

Section: Discussionmentioning

confidence: 99%

Combiningin vivoandin vitroapproaches to better understand host-pathogen interactions

Holdbrook,

Reavey,

Randall

et al. 2024

Preprint

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Nutrition often shapes the outcome of host-parasite interactions, however understanding the mechanisms by which this occurs is confounded by the intimate nature of the association and by the fact that the host and parasite may compete for the same limiting nutrients. One way of disentangling this interaction is to combine in vivo and in vitro approaches. Here, we explore the role of host nutrition in determining the outcome of infections using a model insect-bacterium system: the cotton leafworm Spodoptera littoralis and the blood-borne bacterium Xenorhabdus nematophila. Spodoptera littoralis larvae were reared on one of a series of 20 chemically-defined diets ranging in their protein: carbohydrate (P:C) ratio and caloric density. They were then challenged with either a fixed dose of X. nematophila cells (live or dead) or were sham-injected. Survivorship of larvae challenged with live bacterial cells was strongly dependent on the protein levels of the diet, with mortality being highest on low-protein diets. This trend was reflected in the bacterial growth rate in vivo, which peaked in larvae fed low-protein diets. To determine whether in vivo bacterial growth rates were driven by blood nutrients, rather than an enhanced host immune response, we generated 20 synthetic haemolymphs (nutribloods) that mimicked the nutritional content of host blood. Bacterial growth rate in the nutribloods was also negatively impacted by their protein content suggesting that nutrient availability and not host immunity was driving the interaction. By comparing standardized bacterial growth rates in vivo and in vitro, we conclude that the outcome of this host-parasite interaction is largely driven by bottom-up effects of nutrients on bacterial growth, rather than by top-down effects of nutrients on host-mediated immune responses. The outcome of host-parasite interactions is typically assumed to be strongly determined by the host immune response. The direct effects of nutrition have been underexplored and may have broad consequences for host-parasite interactions across taxa.

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Section: Discussionmentioning

confidence: 99%

Combiningin vivoandin vitroapproaches to better understand host-pathogen interactions

Holdbrook,

Reavey,

Randall

et al. 2024

Preprint

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show abstract

“…Although identification of nutritional optima is important for in vitro mass culture of microbes, studies investigating microbial nutrient-use usually involve batch cultures with generic media containing multiple nutrients that are varied simultaneously (e.g. (Pulkkinen et al, 2018)) or the modification of a single dietary component (Bowen et al 2012; Kooliyottil et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Nutribloods: novel synthetic lepidopteran haemolymphs for understanding insect-microbe interactionsin vitro

Holdbrook,

Randall,

Reavey

et al. 2024

Preprint

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Understanding the role of nutrients in microbial population dynamics relies on a sound appreciation of their nutritional environment and how this may vary in different habitats. For microbial pathogens and commensals, this can be especially challenging because the microbe may share nutritional resources with its host. Here we design a series of 20 synthetic haemolymphs (nutribloods) that mimic haemolymph nutrient profiles of caterpillars fed on one of 20 chemically-defined diets, that vary in their protein:carbohydrate (P:C) ratio and caloric density. Using these, we are able to simulate the range of nutritional conditions that insect blood pathogens might face, providing a model system for understanding the role of nutrition in microbial growth. We tested this using the entomopathogen, Xenorhabdus nematophila, a gram-positive extracellular bacterium of insect hosts. This revealed that whilst bacterial fitness peaked in nutriblood nutrient space that was high in carbohydrates and low in proteins; levels of amino acids in the nutribloods also appear to be an important driving force for bacterial growth. Using synthetic haemolymphs that had average levels of all nutrients other than carbohydrate, protein or amino acids, we also established that bacterial growth is generally enhanced by carbohydrate and amino acids but reduced by proteins. Here, we have established a tractable model system for examining the role that nutrition plays in the growth of an entomopathogenic bacterium. In future work, this model host-pathogen system can be used to test a range of nutritionally-driven processes, including competition during co-infection and interactions with the host microbiome, as well as comparative studies of other entomopathogens.

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Biodegradation potential of sodium dodecyl sulphate (SDS) by mixed cells in domestic and non-domestic actual wastewaters: Experimental and kinetic studies

Najim

Ismail

Hummadi

2022

Biochemical Engineering Journal

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Physiological Constants of the Entomopathogenic Bacterium Xenorhabdus nematophila Determined by Microbial Growth Kinetics

Cited by 3 publications

References 10 publications

Combiningin vivoandin vitroapproaches to better understand host-pathogen interactions

Combiningin vivoandin vitroapproaches to better understand host-pathogen interactions

Nutribloods: novel synthetic lepidopteran haemolymphs for understanding insect-microbe interactionsin vitro

Biodegradation potential of sodium dodecyl sulphate (SDS) by mixed cells in domestic and non-domestic actual wastewaters: Experimental and kinetic studies

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