Stolze Nicholas, Bader Carly, Henning Christopher, Mastin Jared, Holmes Andrea E, Sutlief Arin L
Doane University, Crete, Nebraska, United States of America.
AgriScience Labs, Denver, Colorado, United States of America.
J Microbiol Methods. 2019 Sep;164:105681. doi: 10.1016/j.mimet.2019.105681. Epub 2019 Aug 2.
Currently, in the state of Colorado and all other states within the United States of America with legalized marijuana programs, testing is required for bacteria, yeast, and mold on marijuana products. The Code of Colorado Regulations, 1 CCR 212-1, considers a passing result when a 1 g sample contains <10 colony forming units (CFU) for the total yeast and mold count (TYMC). These measurements are usually obtained by manually counting colonies on petri-dishes or 3 M™ Petrifilms™, which is a time consuming and user subjective process. Therefore, an automated counting method utilizing ImageJ has been developed for CFU analysis of TYMC on Petrifilms. The performance of this colony counting method was demonstrated by comparing manual and automated counts from marijuana flower samples containing spikes of Candida albicans as well as samples that tested positive for the presence of yeast and mold. Fifteen images of Petrifilms showing various concentrations of colonies were studied by fifteen users at two institutions using both the automated and manual counting methods. All counts from the automated ImageJ procedure were within 12% of those obtained manually. In twelve out of fifteen Petrifilms, the average count of the automated method was statistically similar to the manual counts. The statistical differences of the other three samples were observed to be random and caused by user errors. The automated counting method could be used to quickly count numbers that are as high as 400 CFUs, reducing time of analysis with improved documentation because the images and the electronic colony counts can be saved on a computer or cloud for long term storage and data access.
目前，在美国科罗拉多州以及其他所有实施大麻合法化项目的州，大麻产品需要进行细菌、酵母和霉菌检测。《科罗拉多州法规》（1 CCR 212 - 1）规定，当1克样品中总的酵母和霉菌计数（TYMC）<10个菌落形成单位（CFU）时，检测结果为合格。这些测量通常通过人工计数培养皿或3M™ Petrifilms™上的菌落来获得，这是一个耗时且依赖用户主观判断的过程。因此，已经开发了一种利用ImageJ的自动计数方法，用于对Petrifilms上的TYMC进行CFU分析。通过比较含有白色念珠菌加样的大麻花朵样品以及酵母和霉菌检测呈阳性的样品的手动计数和自动计数，证明了这种菌落计数方法的性能。来自两个机构的15名用户使用自动和手动计数方法，对显示不同菌落浓度的15张Petrifilms图像进行了研究。ImageJ自动程序的所有计数结果与手动计数结果的偏差在12%以内。在15张Petrifilms中的12张中，自动方法的平均计数与手动计数在统计学上相似。观察到其他三个样品的统计差异是随机的，并且是由用户误差导致的。这种自动计数方法可用于快速计数高达400个CFU的数量，减少分析时间并改善记录，因为图像和电子菌落计数可以保存在计算机或云端，以便长期存储和数据访问。
