S142: Butanol Tolerance Gene Hunt: Combining classical genetics with omics

Butanol tolerance is a multigenic trait and genes involved in butanol tolerance can be identified  using transcriptomics.  Transposon mutagenesis enables identification of nonessential but relevant genes based on traditional genetic screens or selections on agar plates containing 1-butanol.  An Escherichia coli transposon library was screened  based butanol hypersensitivity and tolerance. 107 butanol hypersensistive mutants and 13 butanol tolerant variants were identified.  The precise sites of transposon integration were identified using  phage 29 DNA polymerase mediated genomic amplification. Analysis of the various mutants implicated stress responses and the cell surface as important determinants of E. coli tolerance to 1-butanol.   A major class of tolerant genes were  insertions within or polar upon spoT specifying a ppGpp synthetase .  In addition ,  knockout of acrB, encoding an efflux pump component, also conferred 1-butanol tolerance.  Lactobacillus plantarum has higher intrinsic butanol tolerance compared to Escherichia coli.  Inactivation of an spoT  homolog in  Lactobacillus plantarum also lead to a butanol tolerant phenotype.