Mameliella sediminis sp. nov., a novel polyhydroxyalkanoate-accumulating bacterium.

A Gram-stain-negative, strictly aerobic, non-motile, rod-shaped bacterium, capable of producing poly-ß-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).

Rapid response of hydrological loss of DOC to water table drawdown and warming in Zoige peatland: results from a mesocosm experiment.

A large portion of the global carbon pool is stored in peatlands, which are sensitive to a changing environment conditions. The hydrological loss of dissolved organic carbon (DOC) is believed to play a key role in determining the carbon balance in peatlands. Zoige peatland, the largest peat store in China, is experiencing climatic warming and drying as well as experiencing severe artificial drainage. Using a fully crossed factorial design, we experimentally manipulated temperature and controlled the water tables in large mesocosms containing intact peat monoliths. Specifically, we determined the impact of warming and water table position on the hydrological loss of DOC, the exported amounts, concentrations and qualities of DOC, and the discharge volume in Zoige peatland. Our results revealed that of the water table position had a greater impact on DOC export than the warming treatment, which showed no interactive effects with the water table treatment. Both DOC concentration and discharge volume were significantly increased when water table drawdown, while only the DOC concentration was significantly promoted by warming treatment. Annual DOC export was increased by 69% and 102% when the water table, controlled at 0 cm, was experimentally lowered by -10 cm and -20 cm. Increases in colored and aromatic constituents of DOC (measured by Abs(254 nm), SUVA(254 nm), Abs(400 nm), and SUVA(400 nm)) were observed under the lower water tables and at the higher peat temperature. Our results provide an indication of the potential impacts of climatic change and anthropogenic drainage on the carbon cycle and/or water storage in a peatland and simultaneously imply the likelihood of potential damage to downstream ecosystems. Furthermore, our results highlight the need for local protection and sustainable development, as well as suggest that more research is required to better understand the impacts of climatic change and artificial disturbances on peatland degradation.