Composite of PAH-degrading endophytic bacteria reduces contamination and health risks caused by PAHs in vegetables

摘要

Vegetables accumulate polycyclic aromatic hydrocarbons (PAHs) at high concentrations when grown in contaminated sites. Inoculation with PAH-degrading endophytic bacteria (EB_(PAH)) has been recognized as one of the most promising ways to remove PAHs from plant bodies; however, the performance of single endophytic bacteria is generally limited. This investigation used a composite of eight EB_(PAH) to reduce the contamination and health risk posed by 16 EPA priority PAHs in vegetables including Chinese cabbage (Brassica chinensis L.) and pakchoi (Brassica campestris L.). Composite EB_(PAH) have strong PAH degradation abilities, and more than 65% of ∑ PAH were degraded after 10-day insuspension with composite EB_(PAh-) Vegetable were contacted with composite EB_(PAH) by seed soaking (SS) and leaf painting (LP) with an EB_(PAh) cell incubation at OD_(6oo nm) = 0.2-1.5. Compared with those in non-inoculated controls, the ∑ PAH concentrations in edible parts of Chinese cabbage and pakchoi colonized by composite EB_(PAH) via SS and LP with bacterial suspension at OD_(6oo nm) = 0.2-1.5 were 42.07-70.77% and 15.79-53.20% lower, and the incremental lifetime cancer risk (ILCR) values for males and females were 31.78-84.08% and 26.60-83.40% smaller, respectively. SS was the optimal inoculation method for reducing PAH concentrations and ILCR values. Our results indicate that inoculating plants with composite EB_(PAH) can lower the health risk posed by vegetables contaminated with PAHs, and may be used to mitigate plant PAH contamination.