Laboratory and Field Evidence for Long-Term Starvation Survival of Microorganisms in Subsurface Terrestrial Environments
- Biology Dept., New Mexico Inst. of Mining and Technology, Socorro, NM (United States)
- Pacific Northwest National Lab., Richland, WA (United States)
- Department of Biological Sciences, University of Nevada, Las Vegas, NV (United States)
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN (United States)
BIOGEOCHEMICAL MODELING OF GROUNDWATER FLOW AND NUTRIENT FLUX IN SUBSURFACE ENVIRONMENTS INDICATES THAT INHABITANT MICROORGANISMS EXPERIENCE SEVERE NUTRIENT LIMITATION. USING LABORATORY AND FIELD METHODS, WE HAVE BEEN TESTING STARVATION SURVIVAL IN SUBSURFACE MICROORGANISMS. IN MICROCOSM EXPERIMENTS, WE HAVE SHOWN THAT STRAINS OF TWO COMMONLY ISOLATED SUBSURFACE GENERA, ARTHROBACTER AND PSEUDOMONAS, ARE ABLE TO MAINTAIN VIABILITY IN LOW-NUTRIENT, NATURAL SUBSURFACE SEDIMENTS FOR OVER ONE YEAR. THESE NON-SPORE-FORMING BACTERIA UNDERGO RAPID INITIAL MINIATURIZATION FOLLOWED BY A STABILIZATION OF CELL SIZE. MEMBRANE LIPID PHOSPHOLIPID FATTY ACID (PLFA) PROFILES OF THE PSEUDOMONAS ARE CONSISTENT WITH ADAPTATION TO NUTRIENT STRESS; ARTHROBACTER APPARENTLY RESPONDS TO NUTRIENT DEPRIVATION WITHOUT ALTERING MEMBRANE PLFA. TO TEST SURVIVABILITY OF MICROORGANISMS OVER A GEOLOGIC TIME SCALE, WE CHARACTERIZED MICROBIAL COMMUNITIES IN A SEQUENCE OF UNSATURATED SEDIMENTS RANGING IN AGE FROM MODEM TO {gt}780,000 years. Sediments were relatively uniform silts in Eastern Washington State. Porewater ages at depth (measured by the chloride mass-balance approach) were as old as 3,600 years. Microbial abundance, biomass, and activities (measured by direct counts, culture counts, total PLFAs, and radiorespirometry) declined with sediment age. The pattern is consistent with laboratory microcosm studies of Microbial survival: rapid short-term change followed by long-term survival of a proportion of cells. Even the oldest sediments evinced a small but viable Microbial community. Microbial survival appeared to be a function of sediment age. Porewater age appeared to influence the markup of surviving communities, as indicated by PLFA profiles. Sites with different Porewater recharge rates and patterns of Pleistocene flooding had different communities.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 629318
- Report Number(s):
- ORNL/CP-95437; CONF-970706-; ON: DE98001915; TRN: AD-a340 199
- Resource Relation:
- Conference: Annual meeting of the Society of Photo-Optical Instrumentation Engineers, San Diego, CA (United States), 27 Jul - 1 Aug 1997; Other Information: PBD: [Jul 1997]
- Country of Publication:
- United States
- Language:
- English
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