Colifast At-Line Monitor (CALM) - Rapid, online microbial water analysis
The Colifast At-Line Monitor – CALM is a fully automated early warning system for monitoring of coliforms and Pseudomonas aeruginosa in water. Detection time ranges from 2 to 12 hours. The technology is time-saving, cost-reducing, and environmentally friendly. Examples of CALM applications are monitoring of raw water, in-process water, waste water and recreational water. No laboratory facilities and minimal skills in microbiology are required to operate the instrument. The Colifast CALM is easily connected to the system computer or LAN interface. The patented Colifast growth media are supplied in Pre-filled Multi Well Trays™ and the flexibility of the system makes it easy to adapt to different applications. The CALM can perform parallel analysis of different target organisms. Depending on method and test frequency, the CALM needs monthly or weekly refilling of reagents.
The CALM instrument detects and quantifies E. coli, fecal or total coliform bacteria in water by fluorometric monitoring of β-glucuronidase activity (E. coli) or β-galactosidase activity (fecal and total coliforms). The detection of P. aeruginosa is based on substrate hydrolysis of aminopeptidase enzymes present in this bacterium. The Colifast technology is comprised of unique media formulations combined with instrument detection systems. The technology is covered by patents in numerous countries, with several international patents pending. Growth of other bacteria is stopped by inhibitors in the medium and by incubation of the samples at high temperature: Incubator temperatures for selection of thermotolerant coliform bacteria are 44 ° C and total coliforms / E. coli are 37 ° C.
The instrument can perform one of two methods at a time. The Most Probable Number (MPN) method is based on the cultivation of bacteria. A certain volume is added to 4-6 wells of growth medium and the bacterial number is determined from how many of the wells that gave growth after the incubation period (11-12 hours). For the results to be as accurate as possible, it is therefore important that the samples taken on a given source usually give a mixture of positive and negative results.
The rapid method is also a quantitative method, which is based on the enzyme activity of the bacteria present in the water sample. It provides response after 75-115 min and is suitable for water sources where major contamination events can occur.
The CALM is a flexible instrument. This means that the instrument can be adapted to different locations with different occurrence of bacteria. If a source has an average bacterial count of 500 cfu / 100ml, 0.2 ml will usually give a positive test. By injecting about half of this volume, you will often get both positive and negative samples. If the source has lower concentrations of bacteria, the media concentration can be changed so that the sample volume can be as high as 10 ml.
In this way, we ensure good results from the CALM instrument with optimal concentration of media after addition of sample and a sample volume appropriate for the source being measured.