The genome of Desulfotalea psychrophila, a sulfate-reducing bacterium from permanently cold Arctic sediments.

Desulfotalea psychrophila is a marine sulfate-reducing delta-proteobacterium that is able to grow at in situ temperatures below 0 degrees C. As abundant members of the microbial community in permanently cold marine sediments, D. psychrophila-like bacteria contribute to the global cycles of carbon and sulfur. Here, we describe the genome sequence of D. psychrophila strain LSv54, which consists of a 3 523 383 bp circular chromosome with 3118 predicted genes and two plasmids of 121 586 bp and 14 663 bp. Analysis of the genome gave insight into the metabolic properties of the organism, e.g. the presence of TRAP-T systems as a major route for the uptake of C(4)-dicarboxylates, the unexpected presence of genes from the TCA cycle, a TAT secretion system, the lack of a beta-oxidation complex and typical Desulfovibrio cytochromes, such as c(553), c(3) and ncc. D. psychrophila encodes more than 30 two-component regulatory systems, including a new Ntr subcluster of hybrid kinases, nine putative cold shock proteins and nine potentially cold shock-inducible proteins. A comparison of D. psychrophila's genome features with those of the only other published genome from a sulfate reducer, the hyperthermophilic archaeon Archaeoglobus fulgidus, revealed many striking differences, but only a few shared features.

Complete genome sequence of the marine planctomycete Pirellula sp. strain 1.

Pirellula sp. strain 1 ("Rhodopirellula baltica") is a marine representative of the globally distributed and environmentally important bacterial order Planctomycetales. Here we report the complete genome sequence of a member of this independent phylum. With 7.145 megabases, Pirellula sp. strain 1 has the largest circular bacterial genome sequenced so far. The presence of all genes required for heterolactic acid fermentation, key genes for the interconversion of C1 compounds, and 110 sulfatases were unexpected for this aerobic heterotrophic isolate. Although Pirellula sp. strain 1 has a proteinaceous cell wall, remnants of genes for peptidoglycan synthesis were found. Genes for lipid A biosynthesis and homologues to the flagellar L- and P-ring protein indicate a former Gram-negative type of cell wall. Phylogenetic analysis of all relevant markers clearly affiliates the Planctomycetales to the domain Bacteria as a distinct phylum, but a deepest branching is not supported by our analyses.

Microbial degradation of tetraethyl lead in soil monitored by microcalorimetry.

Sieved agricultural soil samples were treated with the anti-knock agent tetraethyl lead (Et4Pb), and the resulting effects were analyzed by microcalorimetry. Et4Pb additions resulted in an increase of the heat production rate, provided that oxygen was present and that the soil was not autoclaved. The increased heat production rate was accompanied by degradation of Et4Pb, as verified by speciation analysis (GC-MS) of the remaining Et4Pb and its ionic degradation products (triethyl lead and diethyl lead cations). Conclusive evidence was obtained that these transformations were mediated mainly by microbes. At an initial Et4Pb concentration of 2 g Pb/kg dry weight the biodegradation rate was about 780 mumol day-1 kg dry weight-1, whilst the chemical decomposition was only 50 mumol day-1 kg dry weight-1. A fivefold rise of the initial Et4Pb concentration resulted in a decrease of the biodegradation rate to 600 mumol day-1 kg dry weight-1 and an increase of the chemical decomposition to 200 mumol day-1 kg dry weight-1. The biodegradation rate was not influenced by the addition of glucose, which means that no indication for a co-metabolic attack of Et4Pb was found.