Tagele Setu Bazie, Gachomo Emma W
Department of Microbiology and Plant Pathology, University of California Riverside, Riverside, CA, 92507, USA.
Environ Microbiome. 2025 Apr 29;20(1):44. doi: 10.1186/s40793-025-00713-6.
Soil microbial communities play key roles in agroecosystems, particularly in processes like organic matter decomposition and nutrient cycling. However, human activities can negatively impact their community structure and, consequently, soil function. SoilGard and Ridomil are effective methods for controlling carrot cavity spots caused by Pythium spp., but their effects on bacterial taxonomic and metabolic function shifts are not well understood. This study aims to investigate the comparative impact of the chemical fungicide Ridomil and the biological fungicide SoilGard on the bacterial communities in soils cultivated with carrots. Our results showed that both SoilGard and Ridomil significantly impacted soil bacterial diversity, but their effects were distinct and time-dependent. Ridomil had an immediate negative effect on soil bacterial diversity two weeks after treatment, whereas SoilGard was initially less disruptive but showed delayed negative consequences 12 weeks after treatment, particularly when combined with Pythium inoculation. Ridomil treatment led to an increase in Proteobacteria, especially the Pseudomonas population, as confirmed by both MiSeq and qPCR data. In contrast, SoilGard depleted the Mycobacterium population at 12 weeks after treatment. Furthermore, the results of community-level physiological profiling using Biolog Ecoplates showed significant differences in substrate-level diversity between Ridomil and SoilGard-treated samples, indicating a shift in the metabolic activity of bacterial communities. Ridomil-treated samples showed the lowest metabolic activity of bacterial communities, based on the diversity and richness of carbon source utilization, compared to control. Overall, this research highlights the distinct and time-dependent effects of biological and chemical fungicides on soil bacterial communities when applied at recommended doses.
土壤微生物群落对农业生态系统起着关键作用，特别是在有机物质分解和养分循环等过程中。然而，人类活动会对其群落结构产生负面影响，进而影响土壤功能。土菌消和甲霜灵是防治由腐霉菌引起的胡萝卜根腐病的有效方法，但它们对细菌分类和代谢功能变化的影响尚不清楚。本研究旨在调查化学杀菌剂甲霜灵和生物杀菌剂土菌消对胡萝卜种植土壤中细菌群落的比较影响。我们的结果表明，土菌消和甲霜灵均对土壤细菌多样性有显著影响，但它们的影响不同且具有时间依赖性。处理两周后，甲霜灵对土壤细菌多样性产生即时负面影响，而土菌消最初干扰较小，但在处理12周后显示出延迟的负面影响，特别是在接种腐霉菌的情况下。MiSeq和qPCR数据均证实，甲霜灵处理导致变形菌门增加，尤其是假单胞菌属种群增加。相比之下，土菌消处理12周后分枝杆菌属种群减少。此外，使用Biolog生态板进行的群落水平生理分析结果表明，甲霜灵和土菌消处理的样品在底物水平多样性上存在显著差异，表明细菌群落的代谢活性发生了变化。与对照相比，基于碳源利用的多样性和丰富度，甲霜灵处理的样品显示细菌群落的代谢活性最低。总体而言，本研究突出了生物和化学杀菌剂在推荐剂量下对土壤细菌群落的不同且具有时间依赖性的影响。
