Exploration of Multidrug Resistance Efflux Pumps (MDREPs) in Tolerance to Biocides
Date
2022-06-14
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Abstract
Biocides are broad-spectrum antiseptics used in industry and increasingly in domestic environments to control microbial growth. Microbial tolerance towards biocides is a well documented phenomenon in industries such as medical, water treatment and food processing but has not been well described in the oil and gas industry. A key form of acquired biocide tolerance is the acquisition of multidrug resistance efflux pumps (MDREPs) through horizontal gene transfer. In this project, I set out to determine if biocide tolerance could be determined and monitored using DNA-based quantitative PCR (qPCR) to facilitate the testing of samples from oil and gas pipelines where biocides are used to control microbiologically influenced corrosion. I first had to design primers for use in qPCR capable of detecting these poorly conserved genes using the annotated genomes of six species (Acetobacterium woodii, Bacillus subtilis, Desulfovibrio vulgaris, Geoalkalibacter subterraneus, Pseudomonas putida and Thauera aromatica) chosen to represent metabolic clades frequently identified in microbiologically influenced corrosion environments. During the creation of the model community, a surprising knowledge gap was identified correlating different microbial growth methods, so the decision was made to use optical density, ATP measurements, DNA concentrations and qPCR targeting 16S rRNA and determine how well these methods agreed. A mixed community of D. vulgaris, G. subterraneus, P. putida and T. aromatica was successfully grown reproducibly in bioreactors allowing for sessile and planktonic sampling following exposure to sublethal concentrations of biocides. Using the developed primers, the MDREP genes were quantified and ratioed to 16S rRNA copy numbers to track changes in the relative abundance. These results provide a proof-of-concept for the creation of a monitoring program aimed at targeting genetic markers and assessing microbial tolerance to biocides without costly sequencing.
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Keywords
MDREP, efflux, multidrug, tolerance, resistance
Citation
Brown, D. C. (2022). Exploration of Multidrug Resistance Efflux Pumps (MDREPs) in Tolerance to Biocides (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.