An investigation into the arsenic resistance genes of Leptospirillum ferriphilum

[摘要] ENGLISH ABSTRACT: Leptospirillum ferriphilum is a moderately thermophilic, iron-oxidizing bacterium that wasisolated from a continuous-flow biooxidation plant used for the recovery of gold fromarsenopyrite ore concentrates. Over many years of continuous selection, L. ferriphilum andother bacteria associated with this environment developed resistance to high concentrations ofarsenic. We investigated the arsenic resistance genes (ars) of Leptospirillum ferriphilum strainFairview and compared these genes to the ars genes from other Leptospirilli. An arsenicresistance operon (ars operon) was isolated from a L. ferriphilum Fairview genebank. Wediscovered that this ars operon was situated in between divergently transcribed transposase(tnpA) and resolvase (tnpR) genes related to the Tn21 subfamily of transposons. Sequenceanalysis of this transposon ars operon indicated the presence of arsRCDAB genes and anadditional CBS orf, located in between the arsA and arsB genes. The 8.5 kb L. ferriphilumtransposon ars operon (TnLfArs) was shown to be present only in L. ferriphilum strainFairview and none of the other Leptospirillum strains. The TnLfArs conferred resistance toarsenate and arsenite in an Escherichia coli ars mutant. We also showed that the TnLfArs iscapable of transposition in Escherichia coli.

[发布机构] Stellenbosch University