Community microrespirometry and molecular analyses reveal a diverse energy economy in Great Boiling Spring and Sandy's Spring West in the U.S. Great Basin

Abstract

Microrespirometry showed that several organic and inorganic electron donors stimulated oxygen consumption in two ∼80°C springs. Sediment and planktonic communities were structurally and functionally distinct, and quantitative PCR revealed catabolically distinct subpopulations of Thermocrinis. This study suggests that a variety of chemolithotrophic metabolisms operate simultaneously in these springs.

Fig 1

Stimulation of O₂ consumption in GBS and SSW water (A) and sediment slurries (B). Samples (2 ml) were amended to the indicated final concentrations with one of the following electron donors: 1 mM sodium thiosulfate (S₂O₃²⁻) or ammonium chloride (NH₄⁺); organic acid (OA) mixture of formate, acetate, lactate, and propionate (1 mM each); mixture of yeast extract (0.5%, wt/vol) and peptone (0.1%, wt/vol; YE/P); or H₂ or CH₄ (10 μM). Rates of O₂ consumption over 20 min in samples (white bars) and filtered or autoclaved controls (gray bars) are shown. Error bars indicate the standard errors of the means (n = 3). Amendments that exhibited stimulation of O₂ consumption significantly above that of the control (paired t test, α = 0.05) before (*) or after (**) correction for multiple tests (Bonferroni correction) within a given experiment are indicated.

Fig 2

Quantification of 16S rRNA genes (16S) and various putative catabolic genes in Thermocrinis and “Ca. Nitrosocaldus yellowstonii” (“Ca. N. yel.”) in DNA isolated from spring water (A) and sediment (B) of GBS. Bars represent the averages and standard errors of three replicates. Primers and qPCR methods are described in the supplemental material and Tables S1 to S3.