The deterioration of metal working fluids (MWFs) due to the microbial colonization
and degradation is a considerable economic factor in the metal working industry.
Microorganisms (MO) are able to metabolize almost all components of MWFs and
thus lead to a loss of its function by the reduction or depletion of additives. Microbial
growth cannot be avoided completely, although various methods exist to reduce the
bacterial load in MWFs. This paper presents a study on the colonization of MWFs by
bacteria and fungi in an industrial environment. The cooling lubricants have been
periodically examined based on biological and chemical methods. The level of the
total bacterial load in the lubricant is considered as well as the composition of the
species community and its development over the evaluation period. With regard to
the increasing relevance of environment friendly processes, a conventional mineral
oil based MWF has been compared to a product based on renewable resources