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Salinity effects on microbial community structure and on potential rates of arsenate reduction, arsenite oxidation, sulfate reduction, denitrification, and methanogenesis were examined in sediment slurries from two California soda lakes. We conducted experiments with Mono Lake and Searles Lake sediments over a wide range of salt concentrations (25 to 346 g liter−1). With the exception of sulfate reduction, rates of all processes demonstrated an inverse relationship to total salinity. However, each of these processes persisted at low but detectable rates at salt saturation. Denaturing gradient gel electrophoresis analysis of partial 16S rRNA genes amplified from As(V) reduction slurries revealed that distinct microbial...
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A radioisotope method was devised to study bacterial respiratory reduction of arsenate in sediments. The following two arsenic-rich soda lakes in California were chosen for comparison on the basis of their different salinities: Mono Lake (∼90 g/liter) and Searles Lake (∼340 g/liter). Profiles of arsenate reduction and sulfate reduction were constructed for both lakes. Reduction of [73As]arsenate occurred at all depth intervals in the cores from Mono Lake (rate constant [k] = 0.103 to 0.04 h−1) and Searles Lake (k = 0.012 to 0.002 h−1), and the highest activities occurred in the top sections of each core. In contrast, [35S]sulfate reduction was measurable in Mono Lake (k = 7.6 ×104 to 3.2 × 10−6 h−1) but not in Searles...
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Hoeft, S.E., Kulp, T.R., Han, S., Lanoil, B., and Oremland, R.S., 2011, Correction - Coupled arsenotrophy in a hot spring photosynthetic biofilm at Mono Lake, California: Applied and Environmental Microbiology, v. 77, no. 15) , p. 5570.
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Schoepp-Cothenet et al. bring a welcome conceptual debate to the question of which came first in the course of planetary biological evolution, arsenite [As(III)] oxidation or dissimilatory arsenate [As(V)] reduction. However, we disagree with their reasoning and stand by our original conclusion.
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