Antimicrobial mechanism of action of ultrasound technology : a macroscopic, genetic and transcriptomic perspective for the disinfection of (waste)water

Abstract

The overall objective of this Ph.D thesis is the characterisation of the mechanisms of the microbial responses of E. coli K-12 and selected E. coli K-12 isogenic mutants under ultrasound treatments. The aim of this work is to identify the genes that play a crucial role on the stress response of wild types and their specific responses incorporated in the ultrasonic mechanism of action. This will allow the optimisation of this technology and its further use on the disinfection of wastewater. The specific objectives of the proposed research project are the following: Perform quantitative assessments to fully describe the microbial inactivation and recovery dynamics of selected faecal indicators during ultrasound processing and post-processing. • Characterise the major effect of sonication stress on Escherichia coli mutants that miss important genes involved in general stress tolerance. The role of these genes in the protection or sensitivity against ultrasound generated radicals are also assessed. • Identify and quantify the specific regulons, i.e., genomic biomarkers, which play an important role in the microbial stress responses during ultrasound processing with transcriptomic analysis. • Understand the sequence of sonication effects contributing to change in transcription of RNA genes and mutations in the DNA, which may lead to different protein expressions.