Bottom sediments of harbors in the South Korea have been long suspected for metal contamination due to ship-based and urban-based activities for the past several decades. A number of areas have been ...suspected to impair ecosystem services to the local residents and drawn complaints from main stakeholders. Twelve contamination suspected harbors were subject to evaluate the level of contamination of Cr, Ni, Cu, Zn, As, Cd, Pb and Hg. The level of sediment contamination for each metal was evaluated comparing the relative enrichment of a given metal to pollution-insensitive aluminum. Regional background concentration of a given metal was also determined based on its down core measurement and sediment texture. Ecological risk posed by the presence of heavy metals was evaluated using the sediment quality guidelines (SQGs) developed by United States National Ocean and Atmosphere Administration (US NOAA) as benchmarks for evaluating sediment chemistry to aquatic organisms. Cu, Zn, Cd, Pb and Hg in the surface sediment were found to be higher than a factor of 1.5 than background sediments, and the overall metal contaminations of surface sediment can be regarded as medium–high- to high-priority sites in the sense of SQGs.
A strictly aerobic, Gram-stain-negative, pale-golden, rod-shaped bacterium, designated as R18H21
, was isolated from marine sediment collected from the Ross Sea, Antarctica. Strain R18H21
grew at ...4-40 °C (optimum 25 °C), at pH 6.3-9.2 (optimum 7.5-8.5) and in 0.5-6 % (w/v) NaCl (optimum 2 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain R18H21
belonged to the genus Arenibacter, with the highest similarity to two type strains, Arenibacter latericius KMM 426
(96.6 %) and Arenibacter certesii KMM 3941
(96.6 %), and lower similarities (95.2-95.9 %) to five other members of the genus Arenibacter. The major fatty acids were iso-C17 : 0 3-OH, Summed Feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), iso-C15 : 0, iso-C15 : 1 G. The major polar lipids were phosphatidylethanolamine, an unidentified aminolipid and an unidentified phospholipid. The respiratory quinone of strain R18H21
was menaquinone-6. The DNA G+C content was 40.0 mol%. Based on phylogenetic, physiological and chemotaxonomic features, strain R18H21
has been classified as a novel species in the genus Arenibacter, for which the name Arenibacterantarcticus sp. nov. is proposed. The type strain of the novel species is R18H21
(=GDMCC 1.1159
=KCTC 52924
).
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•Two different geometrical configurations of anode was compared.•Vertical geometry of anode position was found better.•Nutritional analysis of sediment showed that degradation isn’t ...always certain.•Acidobacteria and Actinobacteria were also played an important role as exoelectrogens apart from Proteobacteria.
A comparative study of an anode position in a benthic microbial fuel cell (BMFC) was performed. Different geometric alignment of anodes having single, vertical and horizontal in sediment to understand the impact of positional changes on power performances was studied. Vertical anode configuration showed 1.2 and 2.56 fold higher power density than horizontal and single anode system respectively. Internal resistance was also found 389, 421 and 668 Ω for vertical, horizontal and single anode system respectively. This suggests that the vertical configuration of anode system performs better than horizontal configuration. Nutritional analysis shows that organic matter was consumed initially at a high rate at anode position than non-anode position and among them; degradation of an organic matter in vertical anode system is higher than horizontal and single configuration. The final increment of organics in the system depicted the accumulation of complex organics which were difficult to oxidize. Microbial community obtained from 16S rRNA found to have the increment of Alpha-, Betaproteobacteria, and Acidobacteria on an anode over time. The dominance of Acidobacteria further reveals the acidic environment formation inside the sediment chamber. It can be concluded that Acidobacteria is also the dominant communities besides Proteobacteria.
Boka Kotorska Bay is on the UNESCO’s World Heritage List. There are no published papers related to the surface sediment pollution of the Bay. For the first time, elements were measured in surface ...sediments at nine locations in the Bay by the energy dispersive X-ray fluorescence spectrometry (ED-XRF) technique. Si, Fe, Ca, K, Ti, Mn, P, Ba, Cr, Sr, Zn, Rb, Ni, Cu, Pb, As, Sn, Sb, Hg and Cd were quantified in the surface sediments. Sediments were classified as non-polluted or polluted by counting the enrichment factor (EF), metal loading index (MLI) and geo-accumulation index (Igeo) based on the elemental background level of the analyzed elements in the literature, or by the Sediment Quality Guidelines (SQGs) of USEPA (United States Environmental Protection Agency). Based on USEPA’s SQGs, the surface sediment in the entire Bay can be classified as heavily polluted by As and Cr, and non-polluted by Cd and Hg, and, related to the sites, the surface sediment at the Tivat-Arsenal site was heavily polluted and at the Orahovac site was not polluted at all. The PLI (pollution load index) values for the locations of Tivat-Arsenal and Orahovac are in agreement with the conclusion based on USEPA’s SQGs. The results in this paper will establish an initial view of sediment pollution and the state of the Bay’s environment.
A diffusive gradient in thin films (DGT) is a newly developed analytical technique that can isolate and quantify the phosphate ions. A DGT unit comprises two components: the diffusion and binding ...layers. The diffusion layer comprises polyacrylamide hydrogel, whereas the binding layer from the oxide gel of ferrihydrite is impregnated with polyacrylamide gel. The technique employs a thin film of diffusive hydrogel in contact with a binding phase (ferrihydrite) that can bind phosphate ions. The diffusive and binding gels were characterized via infrared spectroscopy. The main peaks of the diffusive gel were observed at 3336 and 1636 cm−1, whereas those of the binding gel were observed at 3332 and 1638 cm−1. The DGT technique was evaluated as a way to quantify the amount of phosphate ions present in an aqueous KH2PO4 solution. After a contact time of 24 h, ferrihydrite exhibited a high affinity for phosphate, with an uptake efficiency of 98.17%. A linear relationship (R2 = 0.9938) was found to exist between the contact time (3−24 h) and uptake efficiency. Within the 0.2-1.2-mgL−1KH2PO4 concentration range, a linear relationship existed between analyte concentration and the mass of phosphate salt accumulated in the binding gel (R2 = 0.9748). The phosphate ion was eluted from the ferrihydrite hydrogel using 0.25-M H2SO4 over 30 min. The DGT unit was used to measure the phosphate level in six marine sediment samples from Jakarta Bay. The results revealed mass accumulation of P-containing compounds in the 1.009−2.4676-μg range.
A novel Gram-stain-negative, non-gliding, facultatively anaerobic and rod-shaped bacterium, designated X7
, was isolated from marine sediment taken from the coast of Weihai, China. Strain X7
grew ...optimally at 28-30 °C, at pH 7.0 and in the presence of 2-3 % (w/v) NaCl. Based on the 16S rRNA gene sequence analysis, strain X7
was a member of the genus Salinimicrobium and was most closely related to the species Salinimicrobium gaetbulicola with a 96.3 % 16S rRNA gene sequence similarity value. The major cellular fatty acids of strain X7
were anteiso-C15 : 0, iso-C15 : 0, anteiso-C17 : 1ω9c, iso-C17 : 1ω9c, C17 : 0 2-OH and iso-C17 : 0 3-OH. The major polar lipids of strain X7
were phosphatidylethanolamine, one unidentified phospholipid, two unidentified aminolipids and five unidentified lipids. The predominant respiratory quinone was MK-6, and the genomic DNA G+C content was 46.7 mol%. Phylogenetic, phenotypic, chemotaxonomic and genotypic results indicated that strain X7
represents a novel species of the genus Salinimicrobium, for which the name Salinimicrobium flavum sp. nov. is proposed. The type strain is X7
(=KCTC 42585
=MCCC 1H00115
).
Coenzyme F430, the prosthetic group of methyl coenzyme M reductase (MCR), is a key compound in methane metabolism. We applied coenzyme F430 as a function-specific biomarker of methanogenesis to ...subsurface marine sediments collected below the sulfate reduction zone to investigate the distribution and activity of methanogens. In addition, we examined the kinetics of the epimerization of coenzyme F430, which is the first stage of the degradation process after cell death, at various temperatures (4, 15, 34, 60 °C) and pH (5, 7, 9) conditions, which cover in situ conditions of drilled sediments used in this study. The degradation experiments revealed that the kinetics of the epimerization well follow the thermodynamic laws, and the half-life of coenzyme F430 is decreasing from 304 days to 11 h with increasing the in situ temperature. It indicates that the native F430 detected in the sediments is derived from living methanogens, because the abiotic degradation of F430 is much faster than the sedimentation rate and will not be fossilized. Based on coenzyme F430 analysis and degradation experiments, the native form of F430 detected in subseafloor sediments off the Shimokita Peninsula originates from living methanogen cells, which is protected from degradation in cells but disappears soon after cell death. The biomass of methanogens calculated from in situ F430 concentration and F430 contents in cultivable methanogen species decreases by 2 orders of magnitude up to a sediment depth of 2.5 km, with a maximum value at ∼70 m below the seafloor (mbsf), while the proportion of methanogens to the total prokaryotic cell abundance increases with the depth, which is 1 to 2 orders of magnitude higher than expected previously. Our results indicate the presence of undetectable methanogens using conventional techniques.
Strain 435ᵀ, a catalase- and oxidase-positive, beige-pigmented, facultatively anaerobic and Gram-stain-negative marine bacterium, was isolated from marine sediment collected in the Arctic ...(8°21′629′′E 72°8′827′′N). The cells of the type strain are short- to curve-rods and able to grow at 4–25 °C, pH 6.0–9.0 and in the presence of 0.5–6.0 % (w/v) NaCl. It can reduce nitrate to nitrite. The predominant isoprenoid quinone was identified as Q-8 and the polar lipids are comprised of phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content is 38.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 435ᵀbelongs to the genus Colwellia. Strain 435ᵀwas found to exhibit 92.1–95.6 % 16S rRNA gene sequence similarities with other species of the genus Colwellia. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness indicated that strain 435ᵀcan be considered to represent a novel species, Colwellia arctica sp. nov., of the genus Colwellia. The type strain is 435ᵀ(=CICC 10860ᵀ = ATCC BAA-2609ᵀ).
Rhodoferax sp. PAMC 29310 was isolated from a surface marine sediment of the East Siberian Sea, Arctic. Whole-genome sequencing of the strain Rhodoferax sp. PAMC 29310 was achieved using PacBio RS II ...and Illumina platform. The resulting complete genome comprised of 4,593,249 base pairs (G + C content of 58.0%) with a single chromosome, 4546 protein-coding genes, 57 tRNAs and 6 rRNA operons. A complete set of genes encoding the enzymes of glycolysis and citric acid cycle were identified. No genes encoding ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and nitrogenase reductase (nif) were present indicating that strain PAMC 29310 is not capable of fixing of carbon and nitrogen. PAMC 29310 genome contains genes for dissimilatory and assimilatory nitrate reduction. Gene encoding choline dehydrogenase enzyme which functions at the first step in the synthesis of betaine, one of the most effective osmoprotectants, was detected. In particular, among the genomes of the genus Rhodoferax strains, gene encoding nitrite reductase (nirK), which reduces nitrite to nitric oxide and tetA gene encoding tetracycline resistance protein involved in the resistance to tetracycline were identified only in the genome of Rhodoferax sp. PAMC 29310. As the first genome from the strain which was isolated from marine sediment in the genus Rhodoferax, investigation of physiological characteristics based on the complete genome sequences will help understand the adaptation of Rhodoferax sp. PAMC 29310 in the marine sediment.
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