BACKGROUND Sharp increases in food production worldwide are attributable to agricultural intensification aided by heavy use of agrochemicals. This massive use of pesticides and fertilizers in combination with global climate change has led to collateral damage in freshwater systems, notably an increase in the frequency of harmful cyanobacterial blooms (HCBs). The precise mechanisms and magnitude of effects that pesticides exert on HCBs formation and proliferation have received little research attention and are poorly constrained. RESULTS We found that azoxystrobin (AZ), a common strobilurin fungicide, can favor cyanobacterial growth through growth inhibition of eukaryotic competitors (Chlorophyta) and possibly by inhibiting cyanobacterial parasites (fungi) as well as pathogenic bacteria and viruses. Meta-transcriptomic analyses identified AZ-responsive genes and biochemical pathways in eukaryotic plankton and bacteria, potentially explaining the microbial effects of AZ. CONCLUSIONS Our study provides novel mechanistic insights into the intertwined effects of a fungicide and eutrophication on microbial planktonic communities and cyanobacterial blooms in a eutrophic freshwater ecosystem. This knowledge may prove useful in mitigating cyanobacteria blooms resulting from agricultural intensification.

中文翻译：

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杀真菌剂嘧菌酯通过改变竞争来促进淡水蓝细菌的优势。

背景技术世界范围内粮食产量的急剧增长归因于大量使用农药的农业集约化。农药和肥料的大量使用与全球气候变化相结合，已导致淡水系统受到附带损害，尤其是有害蓝藻水华（HCBs）发生频率增加。农药对六氯代苯形成和扩散所发挥作用的确切机制和影响程度，几乎没有受到研究关注，而且受到的限制也很有限。结果我们发现，一种常见的嗜球果伞菌素杀真菌剂天青霉素（AZ）可以通过抑制真核竞争对手（Chlorophyta）并可能通过抑制蓝细菌寄生虫（fungi）以及病原细菌和病毒来促进蓝细菌的生长。元转录组学分析确定了真核生物浮游生物和细菌中的AZ反应基因和生化途径，可能解释了AZ的微生物作用。结论我们的研究为杀菌剂和富营养化对富营养化淡水生态系统中微生物浮游生物群落和蓝藻水华的相互影响提供了新颖的机理见解。该知识可能被证明可用于缓解农业集约化所导致的蓝藻水华。