Machado Mary C, Vimbela Gina V, Tripathi Anubhav
Center for Biomedical Engineering, Division of Engineering Brown University, Providence, RI, USA.
Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI, USA.
Environ Technol. 2021 Jun 20:1-8. doi: 10.1080/09593330.2021.1939792.
The concentration of nitrate (NO) in Narragansett Bay has been shown to undergo considerable temporal and spatial variation. However, the dynamics of this flux has never been monitored on a fine-scale (<100 m, < 1 d) or in real-time. Whole-cell bio-reporters are promising candidates for low cost environmental sensing of bioavailable nutrients. Yet difficulties remain in creating sensors for long term deployment in the marine environment. This paper describes the creation and validation of a low-cost sensor using a self-bioluminescent strain of the cyanobacteria 7942 for the direct measurement of bioavailable nitrate. Nitrate bioavailability was measured by monitoring light emission from a luxAB based promotor fusion to glnA using a light to frequency sensor and single board microcontroller. Sensor designs are presented in this manuscript with specific focus on storage, cell viability, and compatibility with the marine environment. Sensors were able to consistently assess nitrate standards as low as 1 ppm (16.3 μM). Using a wavelet denoising approach to reduce white noise and hardware noise, nitrate detection of standards as low as 0.037 ppm (0.65 μM) was achieved. Good sensitivity and low cost make these sensors ideal candidates for continuous monitoring of biological nitrates in estuarine systems.
纳拉甘西特湾的硝酸盐（NO）浓度已显示出经历了相当大的时空变化。然而，这种通量的动态从未在精细尺度（<100米，<1天）或实时进行监测。全细胞生物传感器有望成为生物可利用营养素低成本环境传感的候选者。然而，在制造用于长期部署在海洋环境中的传感器方面仍然存在困难。本文描述了一种低成本传感器的创建和验证，该传感器使用蓝藻7942的自发光菌株直接测量生物可利用的硝酸盐。通过使用光频传感器和单板微控制器监测基于luxAB的启动子与glnA融合后的发光来测量硝酸盐的生物可利用性。本手稿介绍了传感器设计，特别关注存储、细胞活力以及与海洋环境的兼容性。传感器能够持续评估低至1 ppm（16.3 μM）的硝酸盐标准。使用小波去噪方法减少白噪声和硬件噪声，实现了低至0.037 ppm（0.65 μM）的硝酸盐标准检测。良好的灵敏度和低成本使这些传感器成为河口系统中生物硝酸盐连续监测的理想候选者。
