Project description:The genome sequence of psychrophilic Shewanella sediminis revealed the presence of five putative reductive dehalogenases (Rdhs). We found that cell extracts of pyruvate/fumarate-grown S. sediminis cells catalysed reduced methyl viologen-dependent reductive dechlorination of tetrachloroethene (PCE) to trichloroethene (TCE) at a specific activity of approximately 1 nmol TCE min(-1) (mg protein)(-1). Dechlorination of PCE followed Michaelis-Menten kinetics with an apparent Km of 120 ?M PCE. No PCE dechlorination was observed with heat-denatured extract or when cyanocobalamin was omitted from the growth medium; however, the presence of PCE in the growth medium increased PCE transformation rates. Analysis of mutants carrying in-frame deletions of all five Rdhs encoding genes showed that only deletion of Ssed_3769 resulted in the loss of PCE dechlorination activity suggesting that Ssed_3769 is a functional Rdh. This is the first study to show reductive dechlorination activity of PCE in a sediment-dwelling Shewanella species that may be important for linking the flux of organohalogens to organic carbon via reductive dehalogenation in marine sediments.
Project description:Here, we report the draft genome sequence of Anaeromicrobium sediminis DY2726D, isolated from a west Pacific Ocean sediment sample. The genome comprises 4,710,590 bp in 56 contigs, with a G+C content of 31.2%. A total of 3,811 protein-coding sequences were predicted. The genome annotation revealed that DY2726D may represent a marine type of Clostridiaceae.
Project description:A Gram-stain-negative, strictly aerobic, non-motile, rod-shaped bacterium, capable of producing poly-β-hydroxyalkanoate, designated DP3N28-2T, was isolated from the sediment collected from Daya Bay, Guangdong, PR China. Optimal growth occurred at 37-40 °C, pH 6.0 and in the presence of 4 % NaCl. The 16S rRNA gene sequences analysis revealed that DP3N28-2T showed highest similarities with Mameliella alba DSM 23384T (98.3 %), Antarctobacter jejuensis 13-2-B6T (97.2 %), Antarctobacter heliothermus El-219T (96.8 %), Maliponia aquimaris MM-10T (96.7 %), Ponticoccus litoralis CL-GR66T (96.4 %) and Aquicoccus porphyridii L1 8-17T (96.1 %). The predominant fatty acids (>10 %) were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c; 72.1 %) and C16 : 0 (11.0 %). The polar lipids contain phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, one aminophosphlipid, one phospholipid and three unidentified lipids. The respiratory quinone was Q-10. The DNA G+C content was 63.0 mol% (data from the genome sequence). The estimated genome size was 5.12 Mb. The average nucleotide identity values between the DP3N28-2T genome and the genome of M. alba was 81.1 %, while the digital DNA-DNA hybridization value was 23.4 %. The phenotypic, genotypic and chemotaxonomic differences between DP3N28-2T and its phylogenetic relatives indicates that DP3N28-2T should be regarded as representing a novel species of the genus Mameliella, for which the name Mameliella sediminis sp. nov. is proposed. The type strain is DP3N28-2T (=MCCC 1K06218T=KCTC 82804T).
Project description:Light is a source of energy and an environmental cue that is available in excess in most surface environments. In prokaryotic systems, conversion of light to energy by photoautotrophs and photoheterotrophs is well understood, but the conversion of light to information and the cellular response to that information has been characterized in only a few species. Our goal was to explore the response of freshwater Actinobacteria, which are ubiquitous in illuminated aquatic environments, to light. We found that Actinobacteria without functional photosystems grow faster in the light, likely because sugar transport and metabolism are upregulated in the light, while protein synthesis is upregulated in the dark. Based on the action spectrum of the growth effect, and comparisons of the genomes of three Actinobacteria with this growth rate phenotype, we propose that the photosensor in these strains is a putative CryB-type cryptochrome. The ability to sense light and upregulate carbohydrate transport during the day could allow these cells to coordinate their time of maximum organic carbon uptake with the time of maximum organic carbon release by primary producers.