我们以前的研究报道了以新鲜的电化学活性细菌(EAB)悬浮液为传感元件的水毒性测定,它具有很高的灵敏度,在提供水污染预警方面具有很大的前景。然而,因为新鲜EAB悬浮液的制备是耗时的,这些研究不适合现场测定水的毒性。为了解决这个问题,这项研究研究了通过冻干EAB的再水化快速制备EAB悬浮液,并建立了一种基于冻干EAB模型菌株ShewanellaoneidensisMR-1的现场测定水毒性的新方法。结果表明,用于S.oneidensisMR-1冷冻干燥的最佳冷冻保护剂是7.5%(w/v)脱脂奶粉。与新鲜的S.onedisisMR-1相比,冻干的S.onedisisMR-1表现出相似的细胞外电子转移(EET)性能(74.7%±0.3%),并且在最佳冷冻保护剂的情况下对水毒性测定的灵敏度略低(65.8%±2.2%)。通过使用冻干的S.onedisisMR-1实现了水毒性的现场测定,并确定了五种常见有毒污染物(Cd2,Pb2+,Cu2+,苯酚和二氯苯酚)达到0.5mg/L水毒性测定能够抵抗常见的干扰,例如,葡萄糖,乳酸,硝酸盐和亚硝酸盐,在实际应用中表现出很高的精度。
Our previous studies have reported water toxicity determination with a fresh electrochemically active bacteria (EAB) suspension as the sensing element, which exhibits high sensitivity and has great prospects in providing early warning about water pollution. However, because the preparation of fresh EAB suspensions is time-consuming, these studies are not suitable for the on-site determination of water toxicity. To solve this problem, this study investigated the rapid preparation of an EAB suspension by the rehydration of freeze-dried EABs and established a novel method for the on-site determination of water toxicity based on the freeze-dried EAB model strain Shewanella oneidensis MR-1. The results demonstrate that the optimal cryoprotectant for S. oneidensis MR-1 freeze drying is 7.5 % (w/v) skimmed milk powder. Compared with fresh S. oneidensis MR-1, freeze-dried S. oneidensis MR-1 exhibits similar extracellular electron transfer (EET) performance (74.7 % ± 0.3 %) and slightly lower sensitivity for water toxicity determination (65.8 % ± 2.2 %) with the optimal cryoprotectant. On-site determination of water toxicity was realized by using freeze-dried S. oneidensis MR-1, and the detection limits of five common toxic pollutants (Cd2+, Pb2+, Cu2+, phenol and dichlorophenol) reached 0.5 mg/L. Water toxicity determination is capable of resisting common interferences, e.g., glucose, lactate, nitrate and nitrite, and shows high accuracy in practical applications.