Maul A, Block J C
Appl Environ Microbiol. 1983 Nov;46(5):1032-7. doi: 10.1128/aem.46.5.1032-1037.1983.
A study has been carried out on the Moselle River by means of a microtechnique based on the most-probable-number method for fecal coliform enumeration. This microtechnique, in which each serial dilution of a sample is inoculated into all 96 wells of a microplate, was compared with the standard membrane filter method. It showed a marked overestimation of about 14% due, probably, to the lack of absolute specificity of the method. The high precision of the microtechnique (13%, in terms of the coefficient of variation for log most probable number) and its relative independence from the influence of bacterial density allowed the use of analysis of variance to investigate the effects of spatial and temporal bacterial heterogeneity on the estimation of coliforms. Variability among replicate samples, subsamples, handling, and analytical errors were considered as the major sources of variation in bacterial titration. Variances associated with individual components of the sampling procedure were isolated, and optimal replications of each step were determined. Temporal variation was shown to be more influential than the other three components (most probable number, subsample, sample to sample), which were approximately equal in effect. However, the incidence of sample-to-sample variability (16%, in terms of the coefficient of variation for log most probable number) caused by spatial heterogeneity of bacterial populations in the Moselle River is shown and emphasized. Consequently, we recommend that replicate samples be taken on each occasion when conducting a sampling program for a stream pollution survey.
已采用一种基于最可能数法对粪大肠菌群进行计数的微量技术，在摩泽尔河上开展了一项研究。该微量技术是将样品的每个系列稀释液接种到微孔板的所有96个孔中，将其与标准膜过滤法进行了比较。结果显示，由于该方法缺乏绝对特异性，出现了约14%的明显高估。微量技术的高精度（就对数最可能数的变异系数而言为13%）及其相对不受细菌密度影响的特性，使得可以使用方差分析来研究空间和时间细菌异质性对大肠菌群估计的影响。重复样品、子样品、处理和分析误差之间的变异性被视为细菌滴定中变异的主要来源。分离出与采样程序各个组成部分相关的方差，并确定每个步骤的最佳重复次数。结果表明，时间变异比其他三个组成部分（最可能数、子样品、样品间）更具影响力，后三者的影响大致相当。然而，摩泽尔河中细菌种群空间异质性导致的样品间变异性（就对数最可能数的变异系数而言为16%）的发生率得到了展示和强调。因此，我们建议在进行河流污染调查的采样程序时，每次都采集重复样品。
