Journal of Microbiology

, Volume 52, Issue 2, pp 161–168 | Cite as

Sequential immunosuppressive activities of bacterial secondary metabolites from the entomopahogenic bacterium Xenorhabdus nematophila

  • Seonghyeon Eom
  • Youngjin Park
  • Yonggyun KimEmail author
Microbial Pathogenesis and Host-Microbe Interaction


The entomopathogenic bacterium Xenorhabdus nematophila secretes at least eight bacterial metabolites that play crucial roles suppressing target insect immune responses by inhibiting eicosanoid biosynthesis. We analyzed sequential changes in bacterial metabolite production during bacterial growth and analyzed their individual immunosuppressive activities against the insect host, Spodoptera exigua. X. nematophila exhibited a typical bacterial growth pattern in both insect host and culture medium, and eight metabolites were secreted at different time points. At the early growth phase (6–12 h), Ac-FGV and PHPP were detected in significant amounts in the culture broth. At this early phase, both Ac-FGV (18 μg/ml) and oxindole (110 μg/ml) levels significantly inhibited phenoloxidase and phospholipase A2 activities in S. exigua hemolymph. At the late growth phase (12–36 h), all eight metabolites were detected at significant levels (10–140 μg/ml) in the culture broth and were sufficient to induce hemocyte toxicity. These results suggest that X. nematophila sequentially produces immunosuppressive metabolites that might sequentially and cooperatively inhibit different steps of insect immune responses.


insect immune immunosuppression Xenorhabdus nematophila hemocyte benzylideneacetone 


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Copyright information

© The Microbiological Society of Korea and Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Department of Bioresource SciencesAndong National UniversityAndongRepublic of Korea

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