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Description and validation of a rapid (1 h) flow cytometry test for enumerating thermophilic bacteria in milk powders
Author(s) -
Flint S.,
Walker K.,
Waters B.,
Crawford R.
Publication year - 2007
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2006.03167.x
Subject(s) - thermophile , library science , test (biology) , research centre , biology , bacteria , computer science , ecology , genetics
Aims: The aim of this study was to develop a rapid assay for enumerating thermophilic bacteria in milk powder. Methods and Results: The BactiFlow TM flow cytometer was used to count bacteria based on esterase activity in viable bacterial cells. A protocol for total viable bacteria was modified by heat‐treating the sample to selectively label thermophilic bacteria. Samples of milk powder dissolved in 0·1% peptone were treated with 0·8% ethylenediaminetetraacetic acid to reduce background interference because of denatured milk proteins. Either thermophilic bacteria were added to the dissolved milk powder or milk powder solutions were incubated at 55°C for 2–3 h to enrich the natural thermophile population for testing. Results from the BactiFlow were compared with traditional plate count results. Conclusions: Thermophilic bacteria in milk powder can be enumerated within 1 h using the BactiFlow flow cytometer. Significance and Impact of the Study: Microbiological test results obtained within 1 h can potentially be used to monitor manufacturing processes, effectively trace problems and provide confidence in the manufacture of product.