Water potential and starvation stress in deep subsurface microorganisms
Nine intact core samples, collected aseptically from depths of 10--436 m near the Savannah River Plant in South Carolina, were tested for water potential, microbial numbers, and microbial activity. Although all samples were collected from below the water table, two samples (a Pee Dee clay from 238 m and a Middendorf clay from 324 m) showed unsaturated conditions ({minus}2.7 and {minus}2.1 MPa, respectively). Both of these samples had very low numbers of culturable cells, low microbial biomass (ATP assay), and low microbial activities (measured as respiration), suggesting that low metric waterpotentials in these strata are limiting factors to microorganisms. An Acinetobacter sp. isolated from the 324 m depth was found to maintain viability under starvation conditions in sterilized aquifer material, even when subjected to severe desiccation ({minus}22 MPa). A Pseudomonas sp., with the ability to oxidize thiosulfate to sulfate, was isolated from the 378 m Middendorf clay sample. This organism survived nutrient deprivation reasonably well; however, the presence of thiosulfate appeared to interfere with its normal ability to maintain viability by endogenous metabolism. Cells cultured in the presence of thiosulfate did not undergo dwarfing and cell viability declines. These are two examples of indigenous subsurface microorganisms, each with different adaptations for long-term survival under conditions of desiccation and/or starvation.
- Research Organization:
- New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Biology
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG04-88ER60711
- OSTI ID:
- 10167311
- Report Number(s):
- CONF-900171-5; ON: DE92018869
- Resource Relation:
- Conference: 1. international symposium on microbiology of the deep subsurface,Orlando, FL (United States),15-18 Jan 1990; Other Information: PBD: [1990]
- Country of Publication:
- United States
- Language:
- English
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