Eradication of Microbial Contamination in Metal Working Fluids

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In many manufacturing processes, metal working fluids are applied to ensure reduced tool wear and workpiece quality. Worldwide, more than half a billion gallons of metal working fluids are estimated to be consumed annually. However, microbial contamination is a significant factor in the degradation of these fluids, causing biofouling and corrosion of equipment, degradation of metal working fluids, imperilment of product quality, and posing occupational safety risks. Once metal working fluids are microbially contaminated, removing bacteria is a difficult task. Residual bacteria can quickly repopulate, even after meticulous cleaning and recharge procedures. Biofilms within the inaccessible regions of a working fluid system are likely responsible for the rapid post-cleaning repopulation. Biofilms are attached microbial communities whose function depends on complex social interactions. Quorum sensing provides the means for biofilm cells to communicate and collectively control group behavior. This award supports fundamental research on quorum quenching strategies to inhibit biofilm formation. Research results can help to increase the sustainability of metal working fluids, reduce waste, and help limit occupational exposure to potentially pathogenic bacteria inhabiting metal working fluids.The first research objective is to establish the relationship between the concentration of quorum quenching agent and the efficacy of the agent on biofilm eradication. A suite of quorum quenching agents (i.e., emodine, acylase, and a-amylase) will be studied in a testing matrix of eight rows and twelve columns. The concentration will be varied beginning with the manufacturer's suggested dosage for planktonic organisms. Model biofilm organisms (i.e., Pseudomonas fluorescens and Bacillus subtilis) grown in a metal working fluid will be used. The efficacy of an agent on biofilm eradication will be evaluated by the agent's minimal inhibition concentration for biofilm removal using a microplate absorption spectroscopy biofilm removal assay. The second research objective is to determine the action mode of biofilm eradication. It is unknown whether the quorum quenching agents prevent the initial establishment of biofilms on a surface or they disrupt and remove an already established biofilm. Using confocal laser microscopy and Imaris and MetaMorph image analysis software, biofilm formation and disruption will be analyzed in real-time using a drip flow reactor.