Microbial growth and accumulation in industrial metal-working fluids

Abstract

The dynamics of microbial growth in metal-working fluids (MWF) and the effect of the addition of biocides were studied in large fluid systems, in this case, one central tank which holds 150 m3. In this system, populations of Pseudomonas pseudoalcaligenes (>108 CFU/ml) were sustained for a year, although large quantities of biocides were added. Quantitation of 3-OH lauric acid, a marker for many Pseudomonas spp., by gas chromatography indicated that the bacterial biomass exceeded the viable counts by approximately 15 times. Fungi were grown on several occasions, the dominating genera being Fusarium and Candida. Soon after the old MWF was removed and the tank was provided with fresh MWF, which consisted of an emulsion of mineral oil in water, there was a massive growth of P. pseudoalcaligenes that reached levels of >108 bacteria per ml. Initially, only low concentrations of other species were found for some weeks. After this period, different enterobacteria and other gram-negative rods often appeared at high concentrations (107 and 108 bacteria per ml, respectively). Bacteria identified as P. pseudoalcaligenes showed great variation with respect to colony morphology and a certain heterogeneity with respect to biochemical characteristics. Certain bacterial species grew as microcolonies on metal strips immersed in the circulating MWF, but P. pseudoalcaligenes was not recovered from this habitat. The total bacterial count in the air surrounding the machines in the metal-working shop showed an inverse relation to increasing distance from the machine. The concentration of bacteria in the air varied because of the number of machines in use, temperature, and humidity. Peak values of more than 105 CFU/m3 of air were recorded. The workshop data combined with experimental studies indicated that the biocide concentrations employed in the MWF were too low to prevent microbial growth of Pseudomonas species, in particular. Stable growth of Pseudomonas spp. facilitated the establishment of other bacteria, such as enterobacteria. New strategies are in demand to prevent microbes from growing in MWF.

Bacterial community structure and function in a metal‐working fluid

“…Conversely, identification of the same populations would enable development of targeted biocides since the spoiling organisms would be known. The results of complementary in situ , genotypic and phenotypic analyses, confirmed the observation of previous studies, that the microbial diversity within MWF is comparatively low, reflecting the highly selective nature of the substrate (Baker et al ., 1983;Baecker et al ., 1989;Mattsby-Baltzer et al ., 1989;van der Gast et al ., 2001).…”

Potential pathogenic bacteria in metalworking fluids and aerosols from a machining facility

“…Acinetobacter spp., Alcaligenes spp., Morganella spp., Ochrobactrum spp., and Staphylococcus spp. have each been isolated from metalworking fluids (Mattsby-Baltzer et al, 1989;Sandin et al, 1991;Laitinen et al, 1999;Bracker et al, 2003), while Brevundimonas spp., Corynebacterium spp., and Ochrobactrum spp. have been identified in metalworking aerosols (Gorny et al, 2004).…”

Extended tracking of the microbial community structure and dynamics in an industrial synthetic metalworking fluid system

“…The majority of the past studies on microbial diversity in the industrial machining fluids have been performed based on random batch sampling with little information on tracking (Mattsby-Baltzer et al, 1989b;Lonon et al, 1999;van der Gast et al, 2003;Veillette et al, 2004;Cyprowski et al, 2007;Perkins & Angenent, 2010;Gilbert et al, 2010;Murat et al, 2012;Saha & Donofrio, 2012).…”