Description of the novel perchlorate-reducing bacteria Dechlorobacter hydrogenophilus gen. nov., sp. nov. and Propionivibrio militaris, sp. nov.

Abstract

Novel dissimilatory perchlorate-reducing bacteria (DPRB) were isolated from enrichments conducted under conditions different from those of all previously described DPRB. Strain LT-1T was enriched using medium buffered at pH 6.6 with 2-(N-morpholino)ethanesulfonic acid (MES) and had only 95% 16S rRNA gene identity with its closest relative, Azonexus caeni. Strain MPT was enriched in the cathodic chamber of a perchlorate-reducing bioelectrical reactor (BER) and together with an additional strain, CR (99% 16S rRNA gene identity), had 97% 16S rRNA gene identity with Propionivibrio limicola. The use of perchlorate and other electron acceptors distinguished strains MPT and CR from P. limicola physiologically. Strain LT-1T had differences in electron donor utilization and optimum growth temperatures from A. caeni. Strains LT-1T and MPT are the first DPRB to be described in the Betaproteobacteria outside of the Dechloromonas and Azospira genera. On the basis of phylogenetic and physiological features, strain LT-1T represents a novel genus in the Rhodocyclaceae; strain MPT represents a novel species within the genus Propionivibrio. The names Dechlorobacter hydrogenophilus gen. nov., sp. nov and Propionivibrio militaris sp. nov. are proposed.

Magnetospirillum bellicus sp. nov., a Novel Dissimilatory Perchlorate-Reducing Alphaproteobacterium Isolated from a Bioelectrical Reactor

“…T could grow under both mixotrophic and autotrophic conditions with hydrogen coupled to perchlorate reduction, which has been described for only three other pure cultures (39,45). Figure 4 shows chemolithotrophic growth of strain VDY T with hydrogen as the electron donor and perchlorate as the sole terminal electron acceptor in the bicarbonate-buffered medium described above.…”

“…Given that various elements of the pathway may be mobile, it is not unreasonable to expect that organisms with a wide phylogenetic diversity could acquire the ability to reduce perchlorate. As more varied enrichment conditions are tested (2,39), sometimes as a result of novel bioreactor development for perchlorate treatment (38,40,45), the true phylogenetic diversity of DPRB is becoming apparent, supporting the hypothesis that the metabolism may be widespread within the tree of life, similar to other respiratory processes, such as the reduction of sulfate, Fe(III), and nitrate.…”

“…As a consequence, bioremediation of perchlorate has been identified as the most effective means of treating this harmful contaminant (10), which, due to historically unregulated release into the environment, has become widespread (13,20,41). Fortunately, DPRB are ubiquitous and can be readily isolated from a variety of environments (1,10,11,39,44), and a key gene in the pathway, the chlorite dismutase (cld) gene, has been broadly detected (6). Much has been revealed about the biochemistry and genetics of microbial perchlorate reduction through the study of several model organisms, including Dechloromonas aromatica and Dechloromonas agitata, by a variety of groups (5,6,8,9,17,28,29,34,35,38, 47, 51, 56, 57).…”

A novel perchlorate- and nitrate-reducing bacterium, Azospira sp. PMJ

“…HCAP-C could be effective for reducing perchlorate at high concentrations, e.g., 1360 mg ClO 4 − /L, but would not be effective at low concentrations (below 200 mg ClO 4 − / L) (Dudley et al 2008). Dechlorobacter hydrogenophilus LT-1 T and Propionivibrio militaris MP T were utilized for treating perchlorate in the range of 300∼1000 and 400∼1100 mg ClO 4 − /L, respectively (Thrash et al 2010). In contrast, Azospira sp.…”

“…PDX) and non-PS-type (strain LT-1) (Bardiya and Bae 2011;Coates and Achenbach 2004). The strain LT-1 has recently been re-named as Dechlorobacter hydrogenophilus LT-1 T , and novel PCRB Propionivibrio militaris MP T was identified based on 16S rRNA gene sequence and their biochemical characteristics (Thrash et al 2010). The α-Proteobacteria is represented mainly by Dechlorospirillum spp.…”