Fluorescence spectroscopy as a tool for determining microbial quality in potable water applications

Building on previous work where fluorescence spectroscopy has been used to detect sewage in rivers, a portable LED spectrophotometer was used for the first time to establish bacterial numbers in a range of water samples. A mixed-method approach was used with standard bacteria enumeration techniques on diluted river water and sewage works final effluent using a number of diluents (Ringer's solution, tap water and potable spring water). Fluorescence from uncultured dilutions was detected at a 280 nm excitation/360 nm emission wavelength (corresponding to the region of tryptophan and indole fluorescence) and compared with bacteria numbers on the same cultured sample. Good correlations were obtained for total coliforms, E. coli and heterotrophic bacteria with the portable LED spectrophotometer (R2=0.78, 0.72 and 0.81 respectively). The results indicate that the portable spectrophotometer could be applied to establish the quality of drinking water in areas of poor sanitation that are subject to faecal contamination, where infrastructure failure has occurred in the supply of clean drinking water. This would be particularly useful where laboratory facilities are not at hand.

本研究在既往利用荧光光谱法检测河流中污水的研究基础上，首次采用便携式LED分光光度计(portable LED spectrophotometer)对多种水样中的细菌数量进行定量测定。研究采用混合研究方法，使用林格氏液、自来水及饮用泉水等多种稀释剂，对稀释后的河水与污水处理厂最终出水开展标准细菌计数实验。在激发波长280 nm/发射波长360 nm（对应色氨酸与吲哚的荧光区域）下，检测到未培养稀释液的荧光信号，并将其与同一培养样本的细菌数量进行对比分析。便携式LED分光光度计对总大肠菌群、大肠杆菌(E. coli)及异养细菌的检测结果均呈现良好相关性，决定系数R²分别为0.78、0.72与0.81。研究结果表明，该便携式分光光度计可应用于卫生设施匮乏且遭受粪便污染的区域——即清洁饮用水供应基础设施出现故障的地区——的饮用水水质评估，在缺乏实验室配套条件的场景下具备显著应用价值。