Description
This laboratory method for the detection of micro-organisms in fuels corresponds to the IP 385/19: "Enumeration of living micro-organisms in middle distillates and their associated waters. Method of filtration and culture".
This standard describes two methods A and B for the enumeration of germs in middle distillates.
The A method allows a count in middle distillates up to 50,000 CFU/L for moulds, and up to 100,000 CFU/L for bacteria and yeasts.
After filtration of a known volume of fuel through a membrane filter, the filters are placed directly on nutrient agar plates.
Method B is used for the enumeration of aerobic micro-organisms in the aqueous phase associated with the fuel. It is valid for a count of up to 5.10⁸ CFU/ml for moulds and 1.10⁹ CFU/ml for bacteria and yeasts separately.
After separation of the aqueous phase, successive dilutions are made and then inoculated directly onto nutrient agars.
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