title: Essential Amino Acid Supplementation by Gut Microbes of a Wood-Feeding Cerambycid.
abstract: Insects are unable to synthesize essential amino acids (EAAs) de novo, thus rely on dietary or symbiotic sources for them. Wood is a poor resource of nitrogen in general, and EAAs in particular. In this study, we investigated whether gut microbiota of the Asian longhorned beetle, Anoplophora glabripennis (Motschulsky), a cerambycid that feeds in the heartwood of healthy host trees, serve as sources of EAAs to their host under different dietary conditions. δ(13)C-stable isotope analyses revealed significant δ(13)C-enrichment (3.4 ± 0.1‰; mean ± SEM) across five EAAs in wood-fed larvae relative to their woody diet. δ(13)C values for the consumers greater than 1‰ indicate significant contributions from non-dietary EAA sources (symbionts in this case). In contrast, δ(13)C-enrichment of artificial diet-fed larvae (controls) relative to their food source was markedly less (1.7 ± 0.1‰) than was observed in wood-fed larvae, yet still exceeded the threshold of 1‰. A predictive model based on δ(13)CEAA signatures of five EAAs from representative bacterial, fungal, and plant samples identified symbiotic bacteria and fungi as the likely supplementary sources of EAA in wood-fed larvae. Using the same model, but with an artificial diet as the dietary source, we identified minor supplementary bacterial sources of EAA in artificial diet-fed larvae. This study highlights how microbes associated with A. glabripennis can serve as a source of EAAs when fed on nutrient-limited diets, potentially circumventing the dietary limitations of feeding on woody substrates.
authors.affiliation: Current address: Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, Ohio, 43210 Columbus, OH, USA (akwettey@gmail.com), Department of Entomology and Centre for Chemical Ecology, The Pennsylvania State University, 16802 University Park, PA, USA (tl@leibniz.uni-kiel.de; gwf10@psu.edu; kxh25@psu.edu), kxh25@psu.edu.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Ayayee
authors.affiliation: Christian-Albrechts Universitat zu Kiel, Leibniz-Laboratory for Radiometric Dating and Stable Isotope Research, 24118 Kiel, Germany (tl@leibniz.uni-kiel.de).
authors.forename: Thomas
authors.initials: T
authors.lastname: Larsen
authors.affiliation: Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, University Park, Pennsylvania, PA (czr2@psu.edu).
authors.forename: Cristina
authors.initials: C
authors.lastname: Rosa
authors.affiliation: Department of Entomology and Centre for Chemical Ecology, The Pennsylvania State University, 16802 University Park, PA, USA (tl@leibniz.uni-kiel.de; gwf10@psu.edu; kxh25@psu.edu).
authors.forename: Gary W
authors.initials: GW
authors.lastname: Felton
authors.affiliation: Department of Biochemistry, Microbiology, and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, PA (jgf3@psu.edu), and.
authors.forename: James G
authors.initials: JG
authors.lastname: Ferry
authors.affiliation: Department of Entomology and Centre for Chemical Ecology, The Pennsylvania State University, 16802 University Park, PA, USA (tl@leibniz.uni-kiel.de; gwf10@psu.edu; kxh25@psu.edu), kxh25@psu.edu.
authors.forename: Kelli
authors.initials: K
authors.lastname: Hoover
mesh_terms: D000601:Amino Acids, Essential / Q000378:metabolism*; D000818:Animals; D001517:Coleoptera / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology*; D004032:Diet; D000069196:Gastrointestinal Microbiome; D007814:Larva / Q000378:metabolism / Q000382:microbiology; D014934:Wood
chemical_list: D000601:Amino Acids, Essential
keywords: Anoplophora glabripennis; EAA; gut microbiota; xylophagy; δ13C fingerprint