BiOWiSH Technologies, 2717 Erie Avenue, Cincinnati, OH 45208, USA.
BiOWiSH Technologies, 2717 Erie Avenue, Cincinnati, OH 45208, USA.
J Microbiol Methods. 2020 May;172:105891. doi: 10.1016/j.mimet.2020.105891. Epub 2020 Mar 12.
Aerobic plate count assays are an industry standard method for the enumeration of microbial products. Colony swarming among industrial Bacillus isolates on solid medium can impact a counting technician's interpretation of colony count, promote inter-technician variance and reduce the agreement of plate counts with growth-independent enumeration methods. In the present study, we examined swarming behavior among four industrial Bacillus species as a function of culture medium brand choice. Colony diameter for three Bacillus species was found to be influenced by culture medium brand, as was colony count interpretation among three out of four plate counting technicians. Estimations of Bacillus endospore concentration were likewise influenced by culture medium brand, leading to an increased incidence of QC failure for replicate samples of a Bacillus-based microbial product as a function of brand choice. Results suggest that culture medium brand choice may be an additional source of variance when plate counting is used for the enumeration of Bacillus-based microbial products. We recommend that plating medium brand availability in testing laboratories be considered by microbial product manufacturers when considering sources of variance in customer and regulatory laboratories.
需氧平板计数法是一种用于微生物产品计数的行业标准方法。在固体培养基上，工业芽孢杆菌分离物的菌落扩散会影响计数技术人员对菌落计数的解释，促进技术人员之间的差异，并降低平板计数与生长独立计数方法的一致性。在本研究中，我们研究了四种工业芽孢杆菌的扩散行为与培养基品牌选择的关系。发现三种芽孢杆菌的菌落直径受到培养基品牌的影响，而在四位平板计数技术人员中，有三位的菌落计数解释也受到影响。芽孢杆菌内孢子浓度的估计同样受到培养基品牌的影响，导致作为品牌选择函数的芽孢基微生物产品的重复样本的 QC 失败率增加。结果表明，当使用平板计数法对芽孢基微生物产品进行计数时，培养基品牌选择可能是另一个方差源。我们建议微生物产品制造商在考虑客户和监管实验室的方差来源时，应考虑测试实验室中平板培养基的品牌可用性。
