Insights into organohalide respiration and the versatile catabolism of Sulfurospirillum multivorans gained from comparative genomics and physiological studies

Sulfurospirillum multivorans, a free-living epsilon-proteobacterium, is among the best studied organisms capable of organohalide respiration. It is able to use several halogenated ethenes as terminal electron acceptor. In this report, the complete genome sequence of S.multivorans including a comparison with genome sequences of two related non-dehalogenating species, Sulfurospirillum deleyianum and Sulfurospirillum barnesii, is described. The 3.2Mbp genome of S.multivorans revealed a approximate to 50kbp gene region encoding proteins required for organohalide respiration and corrinoid cofactor biosynthesis. This region includes genes for components not detected before in organohalide-respiring organisms. A transcript analysis of genes coding for some of these proteins indicates the involvement of a putative quinol dehydrogenase in organohalide respiration. The presence of genes encoding a variety of oxidoreductases reflects the organism's metabolic versatility. This was confirmed by growth studies with different electron acceptors including perchlorate and several sulfur-containing compounds. A comparison with other epsilon-proteobacteria indicates horizontal acquisition of many genes in the S.multivorans genome, which might be the basis of the bacterium's catabolic flexibility.