identification by RNA-Seq of PhoP and polymyxin B resistant regulons in Photorhabdus luminescens TT01.

A phoP mutant of the entomopathogenic bacterium P. luminescens is attenuated in virulence in insects and susceptible to antimicrobial peptides such as Polymyxin B. The first goal of this study is to compare transcriptomes of the phoP mutant and wild type strain to identify the PhoP regulon. (i) We first compared both strains grown in LB medium. (ii) As we know that low Mg conditions induce expression of PhoP-dependent genes, we also compared transcriptomes of the phoP and wild-type strain after growth in M9 low Mg and in M9 High Mg. To decipher the polymyxin B regulon, comparisons of transcriptomes of the wild type strain grown in LB medium with or without addition of polymyxin B were also performed Overall design: Two biological replicates of total RNA from exponential cultures (OD= 0.3) of : WT strain grown in LB, phoP mutant grown in LB, WT strain grown in LB plus polymyxin B, WT strain grown in M9 Low Mg, phoP mutant grown in M9 Low Mg Deep sequencing, performed using Illumina HiSeq 2000