Role of Polysulfides in Reduction of Elemental Sulfur by the Hyperthermophilic Archaebacterium Pyrococcus furiosus

摘要

Polysulfides formed through the breakdown of elemental sulfur or other sulfur compounds were found to be reduced to H2S by the hyperthermophilic archaebacterium Pyrococcus furiosus during growth. Metabolism of polysulfides by the organism was dissimilatory, as no incorporation of 35S-labeled elemental sulfur was detected. However, [35S]cysteine and [35S]methionine were incorporated into cellular protein. Contact between the organism and elemental sulfur is not necessary for metabolism. The sulfide generated from metabolic reduction of polysulfides dissociates to a strong nucleophile, HS?, which in turn opens up the S8 elemental sulfur ring. In addition to H2S, P. furiosus cultures produced methyl mercaptan in a growth-associated fashion.