Hydrogen peroxide treatment induces the transposition of an insertion sequence in DY59.

DY59 (formerly DY59) is a radiation-resistant bacterium isolated from soil. From the 3.5 Mb genomic DNA sequence of strain DY59 (December 2014), 31 insertion sequence (IS) elements of six IS families including IS, IS, IS, IS, IS, and IS and five unclassified IS elements were detected. Upon induction of oxidative stress with 80 and 100 mM HO, the unique ISs of the IS family member were actively translocated into a carotenoid biosynthesis gene phytoene desaturase (QR90_10400), resulting in non-pigment phenotypic selection. Therefore, these active transpositions of a specific IS family member were induced by oxidative stress at 80 and 100 mM HO. Furthermore, DY59 exhibited extremely higher MIC values against HO treatment. To explain this phenomenon, qRT-PCR was conducted to assess the expression levels of catalase and three LysR family regulators. Our findings indicated that the IS and IS elements of the IS family were actively transposed into the phytoene desaturase gene by HO treatment replicative transposition. However, high HO resistance did not originate from HO-induced expression of catalase and LysR family regulators.