The ecotoxicological effects of herbicide contamination on the autotrophic growth of microalgae in aquatic environments have been major concerns. However, little is known about the influence of herbicides on the mixotrophic growth of microalgae. This study investigated the ecotoxicological effect of 3-(3,4-dichlorophenyl)−1,1-dimethyl-urea (DCMU) on the mixotrophic growth of Chlorella sacchrarophila FACHB 4. Results showed that C. sacchrarophila in mixotrophy was more resistant to DCMU than in photoautotrophy. Moreover, a low content of DCMU (20–80 μg·L⁻¹) promoted the mixotrophic growth of C. sacchrarophila, and the promotion effect was obviously enhanced with the increase in light intensity. The chlorophyll content and glucose absorption rate of C. sacchrarophila were found to increase after incubation with DCMU for 24 h. Transcriptome analyses revealed that the mechanism of DCMU to promote the mixotrophic growth of C. sacchrarophila was probably through accelerating glucose uptake and utilization, which was accomplished by reducing photodamage and increasing the chlorophyll content of C. sacchrarophila. This study not only revealed an unexpected bloom of mixotrophic microalgae triggered by herbicides, but it also shed new light on an effective and low-cost strategy to improve the microalgae productivity for utilization.

除草剂污染对水生环境中微藻自养生长的生态毒理学影响一直是人们关注的主要问题。然而，关于除草剂对微藻混合营养生长的影响知之甚少。本研究调查了 3-(3,4-二氯苯基)-1,1-二甲基尿素 (DCMU) 对多糖小球藻FACHB 4混合营养生长的生态毒理学影响。结果表明，混合营养的多糖绿藻对DCMU 的抵抗力更强比光合自养。此外，低含量的 DCMU (20–80 μg·L ^{−1 ) 促进了}C. sachrarophila的混合营养生长,且随着光照强度的增加,促进效果明显增强。在与 DCMU 孵育 24 小时后，发现C. sachrarophila的叶绿素含量和葡萄糖吸收率增加。转录组分析表明，DCMU促进C. sachrarophila混合营养生长的机制可能是通过加速葡萄糖的摄取和利用，这是通过减少光损伤和增加C. sachrarophila的叶绿素含量来实现的。这项研究不仅揭示了由除草剂引发的混合营养微藻的意外繁殖，而且还为提高微藻生产力以供利用的有效且低成本的策略提供了新的思路。