A recently published paper ‘Evaluation of heterotrophic plate and chromogenic agar colony counting in water quality laboratories’ in the peer-reviewed journal, Methods X, details how scientists at the Australian Water Quality Centre (AWQC) have for the first time independently validated that results from the ProtoCOL 3 automated colony counter are as accurate as manual colony counting.

The article describes how microbiologists at AWCQ, a leading NATA (National Association of Testing Authorities) accredited water testing laboratory in Adelaide, Australia cultured microorganisms isolated from one hundred water samples on MI agar chromogenic agar and yeast extract agar as an HPC (Heterotrophic Plate Count). The plates were then counted manually and with a ProtoCOL 3 automated colony counter to detect and enumerate total coliforms, E. coli and heterotrophic microorganisms such as bacteria, yeast and moulds.

In total around 1500 counts were performed with the ProtoCOL 3 and by manual counting. The results showed no significant differences in the counting methods for measurement of water quality compliance for either the chromogenic or yeast extract agar plates. Therefore, the AWQC microbiologists concluded in the paper that the sensitivity and specificity of automated counting was comparable to manual counting.

The accuracy of the ProtoCOL 3 in this study is due to the system’s sensitive camera and unique three colour method of imaging, as well as the ProtoCOL 3’s powerful software for analysing the data. It is these features which led the paper’s authors to report that using this automated colony counter could help provide a standard and consistent counting methodology with less operator error; eliminate manual entry of data into a LIMS; improve labour and time efficiency with reduced cost and allow reporting of results to customers more rapidly.

For more details visit: www.sciencedirect.com/science/article/pii/S2215016115000515 or www.synbiosis.com/chromogenic-agar-colony-counting-in-water-quality-laboratories/