Metabolic Plasticity Endows Mixotrophic Organisms with High Tolerance to Cadmium and Special Potential for Recovering Cadmium-Contaminated Aquatic Environment
Metabolic Plasticity Endows Mixotrophic Organisms with High Tolerance to Cadmium and Special Potential for Recovering Cadmium-Contaminated Aquatic Environment
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DOI：
10.1128/aem.00228-23
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发表时间：
2023-06
影响因子：
4.4
通讯作者：
Lu Zhang;Xiaoqing Xu;Yunfei Sun;Yuan Huang;Zhou Yang
中科院分区：
文献类型：
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作者：
Lu Zhang;Xiaoqing Xu;Yunfei Sun;Yuan Huang;Zhou Yang
混合营养生物广泛存在于水生生态系统中，具有独特的生态功能和较强的环境适应性，但其对环境胁迫的抗性机制和生物修复潜力尚不清楚。本研究首次探讨了混合营养体通过生理、种群动态和转录调控对重金属污染物的响应，揭示了混合营养体抵抗和去除重金属的独特机制，从而加深了人们对混合营养体在修复重金属污染水环境中潜力的认识。沃茨中的重金属污染对水生态系统造成严重的胁迫。几种具有较强耐受性的自养生物被广泛应用于重金属的吸附，但由于其营养模式单一，其应用可能受到污染沃茨特定条件的限制。而混合营养体由于其可塑的代谢模式，具有较强的环境适应性。然而，目前对混合营养生物对重金属的抗性及其机制和生物修复潜力的研究还很缺乏。在这项研究中，我们调查了人口，植物生理学和转录组（RNA-Seq）的一个典型的和常见的兼养生物，Ochromonas，镉暴露，然后评估其能力，以消除镉在兼养条件下。与自养相比，混合营养的褐色单胞菌在短时间镉暴露下的光合性能增强，随后随着暴露时间的增加而转向更强的抗性。转录组学分析表明，与光合作用，ATP生产，ECM成分，清除活性氧和受损的细胞器的基因上调，以提高兼养型Ochromonas对镉的抗性。因此，金属暴露的危害最终被降低，并保持细胞的稳定性。大约70%的镉在2.4 mg L−1的镉最终被兼养的棕色单胞菌去除，这得益于与金属离子运输相关的基因上调。因此，混合营养型褐单胞菌对镉的耐受性可以归因于多种能量代谢途径和金属离子的有效运输。总的来说，这项研究推进了更好地了解的重金属抗性的独特机制，在镉污染的水生生态系统的恢复及其潜在的用途。混养生物广泛存在于水生生态系统中，具有独特的生态功能和较强的环境适应性，但其潜在的抗性机制和对环境胁迫的生物修复潜力尚不清楚。本研究首次探讨了混合营养体通过生理、种群动态和转录调控对重金属污染物的响应，揭示了混合营养体抵抗和去除重金属的独特机制，从而加深了人们对混合营养体在修复重金属污染水环境中潜力的认识。混合营养体的这些独特性质对于水生生态系统的长期功能稳定性至关重要。
Mixotrophs widely living in aquatic ecosystems possess unique ecological roles and strong environmental adaptability due to their plastic metabolic modes; however, little is known about their underlying resistance mechanism and bioremediation potential in response to environmental stresses. For the first time, this work investigated how mixotrophs respond to metal pollutants through physiological, population dynamics, and transcriptional regulation, and highlighted the unique underlying mechanism of mixotrophs to resist and remove heavy metal, thereby advancing our understanding of the potentials of mixotrophs in recovering metal-contaminated aquatic environments. ABSTRACT Heavy metal pollution in waters causes serious stress to aquatic ecosystems. Several autotrophs with strong tolerance are extensively used to adsorb heavy metals, but their use may be limited by the specific conditions of polluted waters due to their single nutrition mode. By contrast, mixotrophs possess strong environmental adaptability due to their plastic metabolic modes. However, studies focusing on mixotroph’s resistance and its underlying mechanism in response to heavy metals and their bioremediation potentials are currently lacking. In this study, we investigated the population, phytophysiological, and transcriptomic (RNA-Seq) responses of a typical and common mixotrophic organism, Ochromonas, to cadmium exposure and then evaluated their capacity to remove cadmium under mixotrophic condition. Compared with autotrophy, mixotrophic Ochromonas enhanced photosynthetic performances under short-time cadmium exposure and subsequently shifted to stronger resistance with increasing exposure time. Transcriptomic analyses suggested that the genes related to photosynthesis, ATP production, ECM components, and scavenging of reactive oxygen species and damaged organelles were upregulated to boost mixotrophic Ochromonas resistance to cadmium. Consequently, the harm of metal exposure was eventually reduced and cellular stability was maintained. Approximately, 70% of cadmium at 2.4 mg L−1 cadmium was removed by mixotrophic Ochromonas in the end, benefiting from upregulated genes associated with the transport of metal ions. Hence, mixotrophic Ochromonas tolerance to cadmium can be attributed to multiple pathways of energy metabolism and effective transport of metal ions. Collectively, this study advanced a better understanding of the unique mechanism of heavy metal resistance in mixotrophs and their potential use in recovering cadmium-contaminated aquatic ecosystems. IMPORTANCE Mixotrophs widely living in aquatic ecosystems possess unique ecological roles and strong environmental adaptability due to their plastic metabolic modes; however, little is known about their underlying resistance mechanism and bioremediation potential in response to environmental stresses. For the first time, this work investigated how mixotrophs respond to metal pollutants through physiological, population dynamics, and transcriptional regulation, and highlighted the unique underlying mechanism of mixotrophs to resist and remove heavy metal, thereby advancing our understanding of the potentials of mixotrophs in recovering metal-contaminated aquatic environments. These unique properties in mixotrophs are essential for the long-term functional stability of aquatic ecosystems.