Identification of novel genes involved in acid resistance in Escherichia coli

Abstract

Acid resistance takes important role for survival in acidic environment such as human stomach or fermentation process. Bacteria exposed to acidic environment enhances acid resistance with diverse metabolic pathways and stress responses, so numerous genes affect acid resistance phenotype. In this thesis, artificial RNA sequences which improve acid resistance were found and novel genes involved in acid resistance in Escherichia coli were identified with library screening by applying acidic stress to artificial small RNA library strains. Also, relevance of newly found novel gene expressions and resistance patterns was observed to identify the mechanism of acid resistance enhancement by target genes. The new trait of cysE gene acting as repressor of E. coli acid resistance was discovered in this study, and its phenotype change depends on other genes in L-cysteine biosynthesis pathway which cysE is involved in.