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Quality Assurance/Quality Control Manual: Ohio Water Microbiology Laboratory

Compliance and Official Methods

The Actinomycetes are a large group of filamentous gram-positive bacteria that resemble fungi because they produce mycelium and dry spores, called conidia. (Madigan and others, 2000). They are considered nuisance organisms for those in the water industry, as they are one of two types of organisms that impart an earthy-musty odor to waters. The odors are caused by two compounds formed during normal actinomycete development, geosmin and 2-methylisoborneol (American Public Health Association, 2010).

The method used for isolation of Actinomycetes from water in the OWML is based on a published method (American Public Health Association, 2010) and a method provided by a commercial supplier of Actinomycetes medium (BD-Difco, Sparks, Maryland, The Difco & BBL Manual, 2009). A double agar layer method is used (Appendix C14) and QC samples described in this method are entered into a QC log specifically for Actinomycetes analysis (Appendix B6). Stock cultures of Streptomycetes albus are used as positive controls. The stock culture is transferred every two months and transfers are recorded in LIMS.