Molecular assessment of salt-tolerant, perchiorate- andnitrate-reducing microbial cultures

摘要

The microbial ecology of enrichment cultures adapted to the removal of perchlorate and nitratefrom high salt solutions and ion-exchange brines was examined over a period of four years usingdenaturing gradient gel electrophoresis and total DNA extraction with cloning and in each casepartial sequencing of the 16S rDNA genes. The cultures studied were a result of enrichment frommarine sediment inoculum initiated in 2001. The resulting enrichment cultures were fedperchlorate, or perchlorate and nitrate, in a 3% (w/v) NaCI defined medium or ion-exchangebrines (5.6% NaCI) containing perchlorate and nitrate with acetate as the electron donor. All ofthe sequences' closest matches in the NCBI GenBank database were to marine or salt-tolerantorganisms. Strains belonging to the genera Halomonas or Marinobacter were found to dominatein cultures that were fed nitrate in addition to perchiorate, but were effectively absent fromcultures fed perchlorate alone. The cultures fed perchlorate as the sole electron acceptor wererelatively diverse with the dominant sequences belonging to the genera Dechloromarinus andDenitromonas. A study examining the effects of growing the cultures on different electronacceptors to the cultures revealed that Denitromonas may be more dominant thanDechloromarinus as the salt-tolerant, perchlorate-reducing organism.