title: Abundant iron and sulfur oxidizers in the stratified sediment of a eutrophic freshwater reservoir with annual cyanobacterial blooms.
abstract: The microbial community in eutrophic freshwater sediment was investigated from a 67-cm-deep sediment core collected from the Daechung Reservoir in South Korea, where cyanobacterial blooms have occurred annually for the past 30 years. The majority of core sediments were characterized by dark-grayish, fine-grained mud with abundant gas-escaped and thinly laminated layers. Intervals of summer and winter seasons were represented by periodic peaks of geochemical profiles of parameters such as grain size and relative carbon mass ratios to various nutrients such as nitrogen, sulfur, and phosphorus. In bacteria, Proteobacteria (66.6%) was the most prevalent phylum, followed by Chloroflexi (8.9%), Bacteroidetes (5.1%), and Spirochaetes (2.6%). Archaea were also abundant, representing approximately half of the total prokaryotes in the sediments. Notably, three Bacteria (Sulfuricurvum, Sideroxydans, and Gallionella) and one Archaea (Thermoplasmata) accounted for 43.4% and 38.4% of the total bacteria and archaea, respectively, implying that iron and sulfur oxidizing microorganisms dominate in this eutrophic freshwater sediment. These results indicate that 1) eutrophic freshwater lakes in monsoon climates undergo a stratified sedimentary process with seasonal and annual variations in geochemical and microbial profiles, and 2) the microbial oxidative metabolism of iron and sulfur is notably active in sediments from a eutrophic lake.
authors.affiliation: College of Biology and the Environment, Co-Innovation Centre for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210-037, China.
authors.forename: Long
authors.initials: L
authors.lastname: Jin
authors.affiliation: Culture Collection Team, Freshwater Bioresources Culture Research Division, Nakdonggang National Institute of Biological Resources, Sangju 37242, Republic of Korea.
authors.forename: Chang Soo
authors.initials: CS
authors.lastname: Lee
authors.affiliation: Cell Factory Research Centre, Korea Research Institute of Bioscience &Biotechnology (KRIBB), Daejeon 34141, Republic of Korea.
authors.forename: Chi-Yong
authors.initials: CY
authors.lastname: Ahn
authors.affiliation: Cell Factory Research Centre, Korea Research Institute of Bioscience &Biotechnology (KRIBB), Daejeon 34141, Republic of Korea.
authors.forename: Hyung-Gwan
authors.initials: HG
authors.lastname: Lee
authors.affiliation: Centre for Water Resource Cycle Research, Korea Institute of Science &Technology (KIST), Seoul 02792, Republic of Korea.
authors.forename: Sanghyup
authors.initials: S
authors.lastname: Lee
authors.affiliation: South Sea Research Institute, Korea Institute of Ocean Science &Technology (KIOST), Geoje 53201, Republic of Korea.
authors.forename: Hyeon Ho
authors.initials: HH
authors.lastname: Shin
authors.affiliation: South Sea Research Institute, Korea Institute of Ocean Science &Technology (KIOST), Geoje 53201, Republic of Korea.
authors.forename: Dhongil
authors.initials: D
authors.lastname: Lim
authors.affiliation: Cell Factory Research Centre, Korea Research Institute of Bioscience &Biotechnology (KRIBB), Daejeon 34141, Republic of Korea.
authors.forename: Hee-Mock
authors.initials: HM
authors.lastname: Oh
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics / Q000254:growth & development; D000458:Cyanobacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D005290:Ferric Compounds / Q000378:metabolism; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D007501:Iron / Q000378:metabolism*; D060106:Lakes / Q000737:chemistry / Q000382:microbiology*; D010084:Oxidation-Reduction; D010758:Phosphorus / Q000378:metabolism; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D056910:Republic of Korea; D012621:Seasons; D013455:Sulfur / Q000378:metabolism*; D013461:Sulfur Oxides / Q000378:metabolism
chemical_list: D005290:Ferric Compounds; D012336:RNA, Ribosomal, 16S; D013461:Sulfur Oxides; C000499:ferric oxide; D010758:Phosphorus; D013455:Sulfur; D007501:Iron