Gan Cristina, Langa Elisa, Ballestero Diego, Pino-Otín María Rosa
Universidad San Jorge, Villanueva de Gállego, 50830 Zaragoza, Spain.
Chemosphere. 2024 Nov;368:143666. doi: 10.1016/j.chemosphere.2024.143666. Epub 2024 Nov 16.
The growing demand for sustainable natural products to replace harmful synthetic ones requires comprehensive ecotoxicity assessments to ensure their eco-friendly nature. This study explored for the first time the changes in microbial community growth and metabolic profiles from river and natural soil samples exposed to the two structural isomers, thymol (THY) and carvacrol (CARV), utilizing Biolog EcoPlate™ assays and 16S rRNA gene sequencing for taxonomic analysis. In addition, we addressed existing ecotoxicity data gaps for these two compounds by using aquatic (Daphnia magna and Vibrio fischeri) and soil (Eisenia fetida and Allium cepa) indicators. Results show acute toxicity of both CARV and THY on all indicators. V. fischeri (LC = 0.59 mg/L) > D. magna (4.75 mg/L) > A. cepa (6.47 mg/L) for CARV, and V. fischeri (LC = 1.71 mg/L) > A. cepa (4.05 mg/L) > D. magna (8.13 mg/L) for THY. E. fetida showed LC = 7.68 mg/kg for THY and 1.04 for CARV. River and soil microbial communities showed resilience, likely because they contain taxa capable of biodegrading these products. No significant growth inhibition effects were observed up to 100 mg/L, though substrate utilization decreased at higher concentrations, particularly for polymers and amines in soil microorganisms and polymers in aquatic communities. Soil microorganisms were more affected than aquatic ones, with CARV being more toxic than THY (EC = THY 94.13 and CARV 29.79 mg/L in soil microorganisms). These findings suggest that an increase in the consumption of these products and their subsequent ecotoxicity effects from environmental discharge should still be monitored before being ruled out. However, long-term effects are unlikely due to microbial degradation of these natural products, potentially reducing risks to other target species and opening the way for their use as substitutes for commercial antibiotics.
对可持续天然产品以替代有害合成产品的需求不断增长，这需要进行全面的生态毒性评估，以确保其生态友好性。本研究首次利用Biolog EcoPlate™ 分析和16S rRNA基因测序进行分类分析，探讨了暴露于百里香酚（THY）和香芹酚（CARV）这两种结构异构体的河流和天然土壤样品中微生物群落生长和代谢谱的变化。此外，我们通过使用水生（大型溞和费氏弧菌）和土壤（赤子爱胜蚓和洋葱）指标，填补了这两种化合物现有的生态毒性数据空白。结果表明，CARV和THY对所有指标均具有急性毒性。对于CARV，费氏弧菌（LC = 0.59 mg/L）>大型溞（4.75 mg/L）>洋葱（6.47 mg/L）；对于THY，费氏弧菌（LC = 1.71 mg/L）>洋葱（4.05 mg/L）>大型溞（8.13 mg/L）。赤子爱胜蚓对THY的LC = 7.68 mg/kg，对CARV的LC = 1.04。河流和土壤微生物群落表现出恢复力，可能是因为它们含有能够生物降解这些产品的分类群。在高达100 mg/L的浓度下未观察到显著的生长抑制作用，尽管在较高浓度下底物利用率下降，特别是对于土壤微生物中的聚合物和胺以及水生群落中的聚合物。土壤微生物比水生微生物受到的影响更大，CARV比THY毒性更大（土壤微生物中THY的EC = 94.13，CARV的EC = 29.79 mg/L）。这些发现表明，在排除这些产品的环境排放对其生态毒性影响之前，仍应监测其消费量的增加。然而，由于这些天然产品的微生物降解，长期影响不太可能发生，这可能会降低对其他目标物种的风险，并为其作为商业抗生素的替代品开辟道路。
