Metagenomic analysis of the pinewood nematode microbiome reveals a symbiotic relationship critical for xenobiotics degradation

Our recent research revealed that pinewood nematode (PWN) possesses few genes encoding enzymes for degrading alpha-pinene, which is the main compound in pine resin. In this study, we examined the role of PWN microbiome in xenobiotics detoxification by metagenomic and bacteria culture analyses. Functional annotation of metagenomes illustrated that benzoate degradation and its related metabolisms may provide the main metabolic pathways for xenobiotics detoxification in the microbiome, which is obviously different from that in PWN that uses cytochrome P450 metabolism as the main pathway for detoxification. The metabolic pathway of degrading alpha-pinene is complete in microbiome, but incomplete in PWN genome. Experimental analysis demonstrated that most of tested cultivable bacteria can not only survive the stress of 0.4% alpha-pinene, but also utilize alpha-pinene as carbon source for their growth. Our results indicate that PWN and its microbiome have established a potentially mutualistic symbiotic relationship with complementary pathways in detoxification metabolism.