Identification and characterisation of bacterial populations of an in-use metal-working fluid by phenotypic and genotypic methodology

In-use metal-working fluids (MWFs) are vulnerable to microbial attack, resu lting in untimely biodeterioration, thus rendering them less effective as c oolants and lubricants. The aim of this study was to investigate the microb ial diversity of in-use emulsifiable oil metal-working fluids, and use the information derived to develop strategies to improve metal-working fluid fo rmulation and longevity, and to improve microbial exploitation for biologic al disposal routes using bioreactors. In-use MWF samples from five differen t metal-working machines were analysed using phenotypic, genotypic, and in situ detection methods to determine total background bacterial communities and the composition of enriched degraders. Of 66 bacterial isolates, 13 spe cies from 8 genera were identified by fatty acid methyl ester (FAME) analys is. Genotypic (total) diversity, determined by denaturing gradient gel elec trophoresis (DGGE), reflected the low diversity shown by FAME analysis. Bot h DGGE and in situ microscopy (fluorescent in situ hybridisation, FISH) rev ealed highly conserved microbial communities in MWF from different machines and applications. (C) 2001 Elsevier Science Ltd. All rights reserved.