Agar medium plating for total viable plate counts

Agar medium plating for total viable plate counts 

It is generally not necessary to determine the genus and species of the microbial contaminants isolated to determine if the fuel tank needs treatment or what treatment to provide. The approximate number of total viable microorganisms present in the system will allow you to make this decision. This can be determined by an agar plate count using selective media. 

Agar plating of the fuel phase to recover microbial growth can be accomplished in two main ways fuel filtration and fuel emulsification, prior to agar media plating. 

The fuel water bottom can be plated directly onto the surface of solid agar media or pour plated with molten (cooled to 50°C) liquid agar. If the microbial counts are suspected to be high, the water bottom should be diluted to 10 to 10 in an appropriate medium such as sterile phosphate buffer prior to plating. Sediment (0.01 to 0.1 g wet weight) can be dissolved in 100 ml of a suitable dilution broth prior to agar plating (Swift, 1988). 

The Institute of Petroleum published the following test method. Standard IP 385/95, for fuel boiling below 390° C  

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