In this work, we fabricated a microbial biosensor with long-term stability, which relied on microbial activity. Activity of the microbe was commonly estimated by LIVE/DEAD assay and the propidium iodide (PI)-stained one was judged as dead. Herein, we proposed the utilization of a physiological state of microbes, which was neither live nor dead but between them. In this state, microbes represented a high PI-stained ratio but still had catalytic ability. This microbial state was obtained by forming the biofilm under the conditions of poor nutrition and low temperature. Thus, the dividing and proliferating ability of the microbes in the biofilm was weak, which was beneficial for long-term stability. This mechanism was further confirmed by the biosensors made from multifarious substrate materials, including graphene-based gel, biomass-based gel, graphite felt, and poly(vinyl chloride). This biosensor was applied to water pollution monitoring in the laboratory for 2 years and then was integrated into a multiparameter water quality monitoring station on a local lake for 2.5 years.

中文翻译：

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如何识别与生物传感有关的微生物的“存活/死亡”状态。

在这项工作中，我们制造了一种具有长期稳定性的微生物生物传感器，该传感器依赖于微生物的活性。通常通过LIVE / DEAD分析评估微生物的活性，将碘化丙锭（PI）染色的微生物判定为死亡。在这里，我们提出了一种利用微生物的生理状态的方法，这种微生物既不是活的也不是死亡的，而是在它们之间。在这种状态下，微生物表现出较高的PI染色率，但仍具有催化能力。通过在营养不良和低温的条件下形成生物膜来获得这种微生物状态。因此，生物膜中微生物的分裂和增殖能力较弱，这对于长期稳定性是有利的。由多种底物材料制成的生物传感器进一步证实了这一机制，这些材料包括石墨烯基凝胶，生物质基凝胶，石墨毡和聚氯乙烯。该生物传感器在实验室中用于水污染监测已有2年，然后在当地湖泊中集成了2.5年的多参数水质监测站。