A Gram-negative, facultatively anaerobic, rod-shaped, dissimilatory chloratereducing bacterium, strain AW-1 T , was isolated from biomass of an anaerobic chlorate-reducing bioreactor. Phylogenetic analysis of the 16S rDNA sequence showed 100 % sequence similarity to Pseudomonas stutzeri DSM 50227 and 986 % sequence similarity to the type strain of P. stutzeri (DSM 5190 T ). The species P. stutzeri possesses a high degree of genotypic and phenotypic heterogeneity. Therefore, eight genomic groups, termed genomovars, have been proposed based upon ∆T m values, which were used to evaluate the quality of the pairing within heteroduplexes formed by DNA-DNA hybridization. In this study, DNA-DNA hybridization between strain AW-1 T and P. stutzeri strains DSM 50227 and DSM 5190 T revealed respectively 805 and 565 % similarity. DNA-DNA hybridization between P. stutzeri strains DSM 50227 and DSM 5190 T revealed 484 % similarity. DNA-DNA hybridization indicated that strain AW-1 T is not related at the species level to the type strain of P. stutzeri. However, strain AW-1 T and P. stutzeri DSM 50227 are related at the species level. The physiological and biochemical properties of strain AW-1 T and the two P. stutzeri strains were compared. A common characteristic of P. stutzeri strains is the ability to denitrify. However, in growth experiments, strain AW-1 T could use only chlorate or oxygen as an electron acceptor and not nitrate, perchlorate or bromate. Strain AW-1 T is the first chlorate-reducing bacterium described that does not possess another oxyanion-reduction pathway. Cell extracts of strain AW-1 T showed chlorate and bromate reductase activities but not nitrate reductase activity. P. stutzeri strains DSM 50227 and DSM 5190 T could use nitrate or oxygen as an electron acceptor, but not chlorate. Chlorate reductase activity, in addition to nitrate reductase activity, was detected in cell extracts of both P. stutzeri strains. Chlorite dismutase activity was absent in extracts of both P. stutzeri strains but was present in extracts of strain AW-1 T . Based on the hybridization experiments and the physiological and biochemical data, it is proposed that strain AW-1 T be classified as a novel species of Pseudomonas, Pseudomonas chloritidismutans sp. nov. The type strain is strain AW-1 T (l DSM 13592 T l ATCC BAA-443 T ).

A chlorate reductase has been purified from the chlorate-reducing strain Pseudomonas chloritidismutans. Comparison with the periplasmic (per)chlorate reductase of strain GR-1 showed that the cytoplasmic chlorate reductase of P. chloritidismutans reduced only chlorate and bromate. Differences were also found in N-terminal sequences, molecular weight, and subunit composition. Metal analysis and electron paramagnetic resonance measurements showed the presence of iron and molybdenum, which are also found in other dissimilatory oxyanion reductases.Pseudomonas chloritidismutans (strain AW-1) is a recently isolated facultative anaerobic chlorate-reducing bacterium (22). In chlorate-reducing bacteria, chlorate is reduced to chlorite by a chlorate reductase, and in a second reaction, chlorite is disproportionated to chloride and oxygen by a chlorite dismutase. Two closely related strains of P. chloritidismutans, Pseudomonas stutzeri DSM 50227 and DSM 5190 T (with 16S ribosomal DNA similarities of 100% and 98.6%, respectively), were not able to grow by dissimilatory chlorate reduction. Accordingly, both P. stutzeri strains lack chlorite dismutase activity. However, in addition to nitrate reductase activity, these strains also showed chlorate reductase activity, which has been observed before for other denitrifying bacteria (6, 15). P. chloritidismutans differed from other (per)chlorate-reducing bacteria in that it was only able to use chlorate as a terminal electron acceptor. Other chlorate-reducing bacteria can also couple the reduction of perchlorate or nitrate to growth (1, 13). Although cell extracts also showed bromate reductase activity, P. chloritidismutans could not grow on bromate (22).Up to now, two enzymes that can reduce chlorate and/or perchlorate have been purified and characterized. A chlorate reductase C has been purified from the denitrifying strain Proteus mirabilis, as well as two nitrate reductases (15). The only known substrate of chlorate reductase C is chlorate, which was reduced to chlorite. It was not demonstrated that Proteus mirabilis was able to couple the reduction of chlorate to growth. A second (per)chlorate reductase has been purified from strain GR-1 (10). Experiments showed that one enzyme is responsible for both chlorate and perchlorate reduction activity. Besides (per)chlorate, nitrate, iodate, and bromate were also reduced by the (per)chlorate reductase of strain GR-1. Perchlorate-grown cells were unable to oxidize nitrate or nitrite, indicating that another nitrate reductase may be involved in nitrate-grown cells (17). The purified chlorate reductase of P. chloritidismutans reported here is the first chlorate reductase derived from a chlorate-reducing bacterium that is capable of only dissimilatory chlorate reduction.P. chloritidismutans (DSM 13592) was grown under strictly anaerobic conditions at 30°C, as described before (1). Strain GR-1 (DSM 11199) was grown as described previously (10, 17). Chlorate (10 mM) was used as the electron acceptor, while acetate (10 mM) was used as the e...

The endogenous danger signal bradykinin was recently found implicated in the development of immunity against parasites via dendritic cells. We here report an essential role of the B(2) (B(2)R) bradykinin receptor in the early immune response against Listeria infection. Mice deficient in B(2)R (B(2)R(-/-) mice) were shown to suffer from increased hepatic bacterial burden and concomitant dramatic weight loss during infection with Listeria monocytogenes. Levels of cytokines known to play a pivotal role in the early phase immune response against L. monocytogenes, IL-12p70 and IFN-gamma, were reduced in B(2)R(-/-) mice. To extend these findings to the human system, we show that bradykinin potentiates the production of IL-12p70 in human monocyte-derived dendritic cells. Thus, we show that bradykinin and the B(2)R play a role in early innate immune functions during bacterial infection.