ABSTRACT
AIMS: To develop a flexible and fast colony forming unit quantification method that can be operated in a standard microbiology laboratory. METHODS AND RESULTS: A miniaturized plating method is reported where droplets of bacterial cultures are spotted on agar plates. Subsequently, minicolony spots are imaged with a digital camera and quantified using a dedicated plug-in developed for the freeware program IMAGEJ. A comparison between conventional and minicolony plating of industrial micro-organisms including lactic acid bacteria, Eschericha coli and Saccharomyces cerevisiae showed that there was no significant difference in the results obtained with the methods. CONCLUSIONS: The presented method allows downscaling of plating by 100-fold, is flexible, easy-to-use and is more labour-efficient and cost-efficient than conventional plating methods. SIGNIFICANCE AND IMPACT OF THE STUDY: The method can be used for rapid assessment of viable counts of micro-organisms similar to conventional plating using standard laboratory equipment. It is faster and cheaper than conventional plating methods.
