Identification of Photorhabdus symbionts by MALDI-TOF MS

Hill, Virginia; Kuhnert, Peter; Erb, Matthias; Machado, Ricardo A. R. (2020). Identification of Photorhabdus symbionts by MALDI-TOF MS. Microbiology, 166(6), pp. 522-530. Society for General Microbiology 10.1099/mic.0.000905

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Species of the bacterial genus Photorhabus live in a symbiotic relationship with Heterorhabditis entomopathogenic nematodes. Besides their use as biological control agents against agricultural pests, some Photorhabdus species are also a source of natural products and are of medical interest due to their ability to cause tissue infections and subcutaneous lesions in humans. Given the diversity of Photorhabdus species, rapid and reliable methods to resolve this genus to the species level are needed. In this study, we evaluated the potential of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of Photorhabdus species. To this end, we established a collection of 54 isolates consisting of type strains and multiple field strains that belong to each of the validly described species and subspecies of this genus. Reference spectra for the strains were generated and used to complement a currently available database. The extended reference database was then used for identification based on the direct transfer sample preparation method and the protein fingerprint of single colonies. High-level discrimination of distantly related species was observed. However, lower discrimination was observed with some of the most closely related species and subspecies. Our results therefore suggest that MALDI-TOF MS can be used to correctly identify Photorhabdus strains at the genus and species level, but has limited resolution power for closely related species and subspecies. Our study demonstrates the suitability and limitations of MALDI-TOF-based identification methods for assessment of the taxonomic position and identification of Photorhabdus isolates.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)
05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP) > Institute of Veterinary Bacteriology
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Biotic Interactions

UniBE Contributor:

Hill, Virginia; Kuhnert, Peter; Erb, Matthias and Machado, Ricardo


500 Science > 580 Plants (Botany)
600 Technology > 630 Agriculture




Society for General Microbiology




Peter Alfred von Ballmoos-Haas

Date Deposited:

24 Jul 2020 09:56

Last Modified:

27 Jul 2020 09:49

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Uncontrolled Keywords:

symbionts; entomopathogenic bacteria; identification of bacteria; Photorhabdus




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