Microbial Diversity in Sediments of Saline Qinghia Lake, China:Linking Geochemical Controls to Microbial Ecoloby

Journal Article · Fri Mar 30 04:00:00 EDT 2007 · Microbial Ecology Projects

OSTI ID:923451

Dong, Hailiang; Zhang, Gengxin; Jiang, Hongchen; Yu, Bingsong; Chapman, Leah R; Lucas, Courtney R; Fields, Matthew W

Saline lakes at high altitudes represent an important andextreme microbial ecosystem, yet little is known about microbialdiversity in such environments. The objective of this study was toexamine the change of microbial diversity from the bottom of the lake tosediments of 40 cm in depth in a core from Qinghai Lake. The lake issaline (12.5 g/L salinity) and alkaline (pH 9.4) and is located on theQinghai-Tibetan Plateau at an altitude of 3196 m above sea level. Porewater chemistry of the core revealed low concentrations of sulfate andiron (<1 mM), but high concentrations of acetate (40-70 mM) anddissolved organic carbon (1596-5443 mg/L). Total organic carbon and totalnitrogen contents in the sediments were approximately 2 and<0.5percent, respectively. Acridine orange direct count data indicated thatcell numbers decreased from 4 x 10(9) cells/g at the water-sedimentinterface to 6 x 10(7) cells/g wet sediment at the 40-cm depth. Thischange in biomass was positively correlated with acetate concentration inpore water. Phospholipid fatty acid (PLFA) community structure analysesdetermined decrease in the proportion of the Proteobacteria and increasein the Firmicutes with increased depth. Characterization of small subunit(SSU) rRNA genes amplified from the sediments indicated a shift in thebacterial community with depth. Whereas the alpha-, beta-, andgamma-Proteobacteria and the Cytophaga/Flavobacterium/Bacteroides (CFB)were dominant at the water-sediment interface, low G + C gram-positivebacteria (a subgroup of Firmicutes) became the predominant group in theanoxic sediments. Both PLFA and the sequence data showed similar trend.The Proteobacteria, CFB, and gram-positive bacteria are present in othersaline lakes, but the presence of Actinobacteria andAcidobacteria/Holophaga in significant proportions in the Qinghai Lakesediments appears to be unique. The archaeal diversity was much lower,and clone sequences could be grouped in the Euryarchaeota andCrenarchaeota domains. The archaeal clones were not related to any knowncultures but to sequences previously found in methane-rich sediments.Acetate-utilizing methanogens were isolated from sediment incubations,and alpha- and gamma-proteobacterial isolates were obtained from a watersample from the lake-bottom (23 m). Our data collectively showed that theobserved diversity and shift in the community structure with depth wascorrelated with geochemical parameters (the redox state and availabilityof electron acceptor and donor). Heterotrophic methanogenesis is possiblyadominant metabolic process in the Qinghai Lake sediments. These resultsreinforce the importance of geochemical controls on microbial ecology insaline and alkaline lake environments.

• Research Organization: COLLABORATION - MiamiU.
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 923451
• Report Number(s): LBNL--60418; BnR: KP1102010
• Journal Information: Microbial Ecology Projects, Journal Name: Microbial Ecology Projects Journal Issue: 1 Vol. 51
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
59 BASIC BIOLOGICAL SCIENCES
ACETATES
ACRIDINE ORANGE
BACTERIA
BINDING ENERGY
BIOMASS
CARBON
CARBOXYLIC ACIDS
ECOLOGY
ELECTRONS
Environmental Genomics Evolutionary Biology Extremophiles FieldStudies Stress Response Sulfate Reducers
GENES
IRON
NITROGEN
PHOSPHOLIPIDS
SALINITY
SEA LEVEL
SEDIMENTS
SULFATES
VALENCE
WATER CHEMISTRY