American Water, Voorhees, NJ 08043, USA.
Appl Environ Microbiol. 2009 Dec;75(23):7385-90. doi: 10.1128/AEM.01728-09. Epub 2009 Oct 9.
Assimilable organic carbon (AOC) is an important parameter governing the growth of heterotrophic bacteria in drinking water. Despite the recognition that variations in treatment practices (e.g., disinfection, coagulation, selection of filter media, and watershed protection) can have dramatic impacts on AOC levels in drinking water, few water utilities routinely measure AOC levels because of the difficulty of the method. To simplify the method, the Pseudomonas fluorescens P-17 and Spirillum sp. strain NOX test bacteria were mutagenized by using luxCDABE operon fusion and inducible transposons to produce bioluminescent strains. The growth of these strains can easily be monitored with a programmable luminometer to determine the maximum cell yield via luminescence readings, and these values can be fitted to the classical Monod growth curve to determine bacterial growth kinetics and the maximum growth rate. Standard curves using acetate carbon (at concentrations ranging from 0 to 1,000 microg/liter) resulted in coefficients of determination (r(2)) between luminescence units and acetate carbon levels of 0.95 for P-17 and 0.89 for NOX. The bioluminescence test was used to monitor reclaimed water, in which average AOC levels range between 150 and 1,400 microg/liter acetate carbon equivalents. Comparison of the conventional AOC assay and the bioluminescent assay produced an r(2) of 0.92.
可同化有机碳（AOC）是控制饮用水中异养菌生长的重要参数。尽管人们认识到处理实践（例如消毒、混凝、过滤介质选择和流域保护）的变化会对饮用水中的 AOC 水平产生巨大影响，但由于该方法的难度，很少有水务公司常规测量 AOC 水平。为了简化方法，使用 luxCDABE 操纵子融合和可诱导转座子使荧光假单胞菌 P-17 和旋螺旋菌 NOX 测试细菌发生突变，产生生物发光菌株。这些菌株的生长可以用可编程光度计轻松监测，通过发光读数确定最大细胞产量，并且这些值可以拟合到经典的 Monod 生长曲线，以确定细菌生长动力学和最大生长速率。使用乙酸碳（浓度范围为 0 至 1,000 微克/升）的标准曲线导致荧光单位与 P-17 的乙酸碳水平之间的决定系数（r（2））为 0.95，与 NOX 的 r（2）为 0.89。生物发光试验用于监测再生水中的 AOC 水平，其平均 AOC 水平在 150 至 1,400 微克/升乙酸碳当量之间。与传统 AOC 测定法和生物发光测定法的比较产生了 r（2）为 0.92。
