Univ. Grenoble Alpes & Centre National de la Recherche Scientifique, LIPhy, F-38000 Grenoble, France.
Univ. Grenoble Alpes & Centre National de la Recherche Scientifique, LIPhy, F-38000 Grenoble, France.
J Microbiol Methods. 2023 Mar;206:106693. doi: 10.1016/j.mimet.2023.106693. Epub 2023 Feb 28.
We present a novel method to automate plating for the Colony Forming Unit (CFU) counting procedure. The apparatus we developed for the application of this method is based on motorized stages and a syringe in order to spread fine drops of a liquid containing a solution of interest on a plate without direct contact with the surface. The apparatus can be used in two different modes. In the the first method which follows the same principle as the classical CFU count, fine drops of liquid are deposited homogeneously on an agar plate and microorganisms are allowed to form colonies. In the second, novel method that we call P, isolated drops of the order of 10 μL containing both the microbes and the nutrient medium are deposited directly on a regular grid on a hard surface (plastic or glass); after incubation, drops that show no sign of growth inside are used to determine the microbes concentration. This new method removes the need for preparing agar surfaces and allows for easy disposal of waste and reuse of consumables. The apparatus is simple to build and use, the plating is fast and the CFU count in both type of plating is extremely reproducible and robust.
我们提出了一种新颖的方法来实现集落形成单位 (CFU) 计数过程的自动接种。我们为该方法应用开发的设备基于电动平台和注射器，以便在不与表面直接接触的情况下将含有感兴趣溶液的微小液滴均匀地涂在平板上。该设备可以在两种不同的模式下使用。在第一种方法中，它遵循与经典 CFU 计数相同的原理，将微小液滴均匀地沉积在琼脂平板上，然后允许微生物形成菌落。在第二种新颖的方法中，我们称之为 P，含有微生物和营养介质的 10 μL 左右的孤立液滴直接沉积在硬表面（塑料或玻璃）上的规则网格上；孵育后，内部没有生长迹象的液滴用于确定微生物浓度。这种新方法无需制备琼脂表面，便于废物处理和耗材重复使用。该设备易于构建和使用，接种快速，两种类型的接种的 CFU 计数都非常可重复且稳定。
