Occurrence and characterization of culturable bacteria and fungi in metalworking environments

Abstract

Modern metalworking fluids (MWFs) provide the breeding ground for microorganisms that could enter the ambient environment via aerosolization. This manuscript describes the occurrence, type, concentration and size distribution of bacteria and fungi in an MWF environment by sampling aerosols and MWF sumps. In this study, computer numerical control (CNC) thread-cutting and grinding processes at a socket-manufacturing plant were investigated. Cladosporium and Aspergillus were the dominant fungal isolates in this study. Peak fungal concentrations (797 CFU/m 3 ) were observed during threadcutting processes, and the most prevalent fungi were in the size range of 2.1-3.3 lm. Moreover, Exiguobacterium spp., Micrococcus spp., and Staphylococcus capitis were the dominant bacterial isolates identified. The most prevalent bacteria were in 4.7-7.0 lm size range. This study indicates that the type of machine tools was not associated with MWF sump microbial concentrations. The total bacterial and fungal contamination in MWF sump samples reached levels of 10 5 CFU/ml. Pseudomonas spp. was the only bacterium identified in the MWF sumps, and Aspergillus, Penicillium, and yeast were the predominate fungi identified.

The microbiology of metalworking fluids

“…Certain metals such as chromium, nickel, and iron used in the non-automotive industry might be associated with the growth of Gram-negative rods. Liu et al (2010) reported that species of Exiguobacterium, Micrococcus, and Staphylococcus capitis were the dominant airborne bacteria in MWF environments. Fungi (yeast and molds) are also found as contaminates in MWFs.…”

“…Fungi are associated with hypersensitivity pneumonitis, asthma, and other allergies. Certain species are also known to produce toxic metabolites such as mycotoxins (Liu et al 2010;NIOSH 2001).…”

Flow Cytometry Is a Powerful Tool for Assessment of the Viability of Fungal Conidia in Metalworking Fluids

“…Liu et al (9) found 1.7 ϫ 10 5 CFU/ml of fungi in in-use contaminated MWF. Fungi in MWF belong to a diverse set of genera, such as Cladosporium, Candida, Cephalosporium, Penicillium, Aspergillus, and Fusarium (8)(9)(10)(11). Some of these fungi are pathogenic and associated with hypersensitivity pneumonitis, asthma, and other allergies or skin and eye infections.…”

Biological and chemical hazards in water-mix metalworking fluids and mists

“…All the bacteria detected in the MWF samples of this study have previously been detected in MWF in other screening studies (Liu et al, 2010;Lodders and Kampfer, 2012). From all samples with successful identification of 16S rRNA, gene fragments it is clear that the bacterial diversity is low.…”

“…Molecular analysis using PCR-DGGE on a collection of bulk MWF samples revealed the presence of bacteria that have all previously been detected in MWF in other studies (Liu et al, 2010;Lodders and Kampfer, 2012). In these samples, Pseudomonads sequences appeared to be dominant accounting for 24% of total DNA fragments analysed.…”