Role of Citrobacter amalonaticus and Citrobacter farmeri in dissimilatory perchlorate reduction.

The article deals with the novel physiological function of dissimilatory perchlorate reduction by strains JB101 and JB109 isolated from a laboratory-enriched mixed consortium originating from a sewage treatment facility. The biochemical and physiological data of the strains showed good correspondence with members of the family Enterobacteriaceae. The partial 16S rDNA sequence of the strains JB101 and JB109 had similarity of 99.8% to Citrobacter amalonaticus and 98% to Citrobacter farmeri, respectively. The results inferred the possibility of Citrobacter spp. to form an important group of dissimilatory perchlorate reducers among the gamma subclass of Proteobacteria, since the majority of the perchlorate reducers belong to two monophyletic groups, Dechloromonas and Dechlorosoma in beta subclass. The perchlorate-grown Citrobacter strains preferred perchlorate to nitrate as an electron acceptor unlike most of the reported dissimilatory perchlorate reducers.