USGS Ohio Water Science Center

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Ohio Water Microbiology Lab

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Ohio Water Science Center

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Quality Assurance/Quality Control Manual: Ohio Water Microbiology Laboratory

Compliance and official methods

The method currently in use for quantitative coliphage analysis by the OWML is the USEPA Method 1602, single-agar layer (SAL) procedure (USEPA, 2001b). This method is generally most suitable for quantification of coliphage in surface-water samples. Antibiotic-resistant E. coli CN-13 (resistant to nalidixic acid) and E. coli Famp (resistant to streptomycin and ampicillin) are used as bacterial hosts for somatic and F-specific coliphage, respectively. The protocol for Method 1602 and forms for regular and QC samples are included in Appendix C12.

The method currently in use for qualitative coliphage analysis by the OWML in larger sample volumes is the USEPA Method 1601, two-step enrichment method (USEPA, 2001a). Sample volumes of 1 L are recommended for detec¬tion of coliphage using this method. Because the SAL method is impractical for sample volumes above 100 mL, the two-step enrichment method is often used for groundwater sample analysis. The same bacterial hosts are used in the two-step enrichment method as are used in the SAL method. The protocol for Method 1601 and forms for regular and QC samples are included in Appendix C13.

Results from coliphage QC samples are recorded in LIMS. Coliphage QC log forms, results for other coliphage QC samples, and coliphage stock enumeration results are kept in the Sample Log Book. Information on media sterility is stored in the Media Log Book. Information on host culture strains is maintained in LIMS.


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