Comparison of dechlorinating anaerobes. Dehalococcoides

Both dehalogenating strains of Dehalococcoides were compared. Strain CBDB1 can grow in synthetic medium with some vitamins and fixed nitrogen whereas strain 195 is grown in complex media. Over 1200 of the 1400 coding regions in strain CBDB1 are also found in strain 195, and there are many regions showing colinearity. Neither strain encoded genes involved in flagellar synthesis, cytochromes, or peptidoglcyan biosynthesis. There are three large integrated elements in CBDB1 as compared to 195 that exhibit unusual GC composition, while 195 has 9 integrated elements as compared to CBDB1. Analysis of the rdh loci that encode reductive-dehalogenase-homologous proteins revealed that strain 195 shares 12 of these loci with strain CBDB1, which has a total of 32 rdh loci. Analysis of the position and orientation indicates that these genes are under intensive selective pressure. Due to the greater number of rdh loci, and because strain CBDB1 can grow on simpler media, it has greater potential as a dechlorinator than strain 195 and may be more useful in bioremediation of contaminated waste sites.