Microbial growth in brake fluids

• Total viable counts, optical densities and pHs of brake fluids were determined using Ate and Allied brake fluids.
• The viscosities of these fluids were also checked at cool and hot temperatures.
• Changing of brake fluid should be observed using the manufacturer’s guide.

Bacterial and fungal growths in brake fluids were studied. Bacteria isolated from used Ate and Allied brake fluids were: Bacillus sp., Actinomyces sp., Micrococcus sp., Serratia sp., Citrobacter sp., Pseudomonas sp., Nocardia sp., Acinetobacter sp., Aeromonas sp. and Alcaligenes sp. Bacteria isolated from unused brake fluids were Bacillus sp., Micrococcus sp., Serratia sp., Citrobacter sp. and Actinomyces sp. There were no fungi isolated from unused brake fluids. Fungi found in used brake fluid were Mucor sp., Geotrichum sp., Aspergillus sp., Cladosporium sp. and Penicillium sp. Average counts for total viable microorganisms in used brake fluid ranged from 1.02 × 105 to 2.16 × 108 cfu ml−1, its average optical density ranged from 0.12 to 0.76, its average pH ranged from 4.3 to 7.8 and its average viscosity ranged from 5.39 to 10.29 cSt while for the unused brake fluid, average counts for viable microbial cells ranged from 1.1 × 105 to 6.0 × 105 cfu ml−1, average values for optical density ranged from 0.07 to 0.36, its average values for pH ranged from 6.5 to 8.4 and its average viscosity values ranged from 12.92 to 14.02 cSt. The use of brake fluid according to the manufacturer’s guide should not be ignored and regulatory agencies should also ensure that the braking system of every vehicle is in order.