Water Testing: Rapid Detection Methods for Heterotrophic Bacteria

Bacterial growth in water distribution systems is a commonly used indication of potential health issues. Gaining an accurate assessment of the heterotrophic bacteria count is crucial for determining how effective water treatment systems are working. Unfortunately traditional testing methods for heterotrophic bacteria are often inaccurate and slow. Below you can discover some of the primary limitations of heterotrophic bacteria testing methods and why advanced rapid detection systems have been developed.

What Are Heterotrophic Bacteria?

Heterotrophic bacteria use organic compounds as their source of energy. This differentiates heterotrophic bacteria from chemoautotrophic bacteria and photoautotrophic bacteria which use carbon dioxide as their source of energy. The vast majority of bacteria are in fact heterotrophic.

Heterotrophic bacteria source energy from alcohol, sugar and organic acids. There are also heterotrophic bacteria which are able to decompose keratin, chitin, lignin and cellulose in order to access the carbon. You can find heterotrophic bacteria in a number of different environments including in the food, water, and soil. 

Why You Need to Test for Heterotrophs

Testing for heterotrophs is important because they can indicate how effectively water is being treated. The presence of heterotrophs alone does not necessarily indicate that the water is diseased. But when heterotrophic organisms are found in concentrations of 500 units per mL or higher it is an indication that problems may exist.

Traditional Methods for Testing Water

There are three traditional methods for testing for the concentration of Heterotrophic Organisms in water. The three testing methods are the spread plate method, pour plate method, and membrane filtration method. Each of these methods do produce reasonable guidelines for the concentration of Heterotrophic Organisms present, but they also have their disadvantages. 

In the case of the spread plate method if an automated spreader is used and there is high growth rate in the heterotrophic bacteria colonies, it can be difficult to perform an accurate count. In the pour plate method the heterotrophic organisms need to temporarily suspended in agar while the media is cooling. While the heterotrophic organisms are suspended agar they may be damaged due to heat shock. Again this can lead to an inaccurate count. 

Using the water filtering method the samples may not be able to pass through the filter which can make obtaining an accurate count difficult. Overall the process of using these methods is labor intensive and can take anywhere from a few hours through to a week. Because the testing method and media used varies the counts from these methods can also be significantly different.

Rapid Detection Microbiological Testing Systems

Because of the flaws with these testing methods, more advanced rapid detection testing systems have been developed. These automated testing systems have the advantage of being easier to operate so they don’t require technicians with advanced skills. The also produce faster and more accurate results. Advanced microbiological testing method uses an optical system to test for fluorescence and color in the water. This is able to produce a number of different assays including total counts for coliforms, yeast, mold, e.Coli and Salmonella. 

Gaining an accurate depiction of heterotrophic bacterial counts is crucial for determining the efficiency of water treatment systems. Advanced rapid detections microbiological systems address the flaws in traditional testing methods, and provide accurate, cost effective and fast heterotrophic bacterial organism counts. 

Contact Biolumix to learn more about rapid detection systems for water testing.

Biolumix
3928 Varsity Dr.
Ann Arbor, MI 48108
Phone: (734) 984-3100
Fax: 734-222-1830
Email: info@mybiolumix.com
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