<i>Bacillus pumilus</i> Reveals a Remarkably High Resistance to Hydrogen Peroxide Provoked Oxidative Stress

<div><p><i>Bacillus pumilus</i> is characterized by a higher oxidative stress resistance than other comparable industrially relevant Bacilli such as <i>B. subtilis</i> or <i>B. licheniformis</i>. In this study the response of <i>B. pumilus</i> to oxidative stress was investigated during a treatment with high concentrations of hydrogen peroxide at the proteome, transcriptome and metabolome level. Genes/proteins belonging to regulons, which are known to have important functions in the oxidative stress response of other organisms, were found to be upregulated, such as the Fur, Spx, SOS or CtsR regulon. Strikingly, parts of the fundamental PerR regulon responding to peroxide stress in <i>B. subtilis</i> are not encoded in the <i>B. pumilus</i> genome. Thus, <i>B. pumilus</i> misses the catalase KatA, the DNA-protection protein MrgA or the alkyl hydroperoxide reductase AhpCF. Data of this study suggests that the catalase KatX2 takes over the function of the missing KatA in the oxidative stress response of <i>B. pumilus</i>. The genome-wide expression analysis revealed an induction of bacillithiol (Cys-GlcN-malate, BSH) relevant genes. An analysis of the intracellular metabolites detected high intracellular levels of this protective metabolite, which indicates the importance of bacillithiol in the peroxide stress resistance of <i>B. pumilus</i>.</p>