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Hydrocarbon Fuel, Diesel and Cooling Waters

Bacteria, yeast and fungi are able to grow in hydrocarbon fuels such as diesel and kerosene particularly where moisture has been introduced. This can lead to potential corrosion of tanks and pipes as well as biofouling and blocking of filters. The most commonly known ‘diesel bug’ organism is Cladosporium (Hormoconis) resinae although other types of bacteria and fungi can grow within the fuel and also cause corrosion, biofouling or blockages.


Biodet is able to test fuel samples using either the IP385: Determination of the viable aerobic microbial content of middle distillate fuels and associated water — Filtration and culture method or an In-house methodology that Biodet has developed which includes the addition of testing for sulphate-reducing bacteria (SRB) and using a dilution series to more accurately determine microbial levels.

Although there are no agreed or regulatory standards for levels of microorganism in fuel, Biodet uses the guidelines from R. A. Stuart Microbial Attack on Ships and Their Equipment. Paper 4 Session. Lloyd’s Register Technical Association, London 1994-95.


Regular monitoring of storage tanks can give you peace of mind about what levels of microorganisms are present in your fuel tanks.


Cooling water samples can also be tested using similar methodologies to determine microbial loading to minimise the risk of potential corrosion.

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