Assimilation of CO2 and introduced organic compounds by bacterial communities in groundwater from southeastern Sweden deep crystalline bedrock
- 1 January 1992
- journal article
- Published by Springer Nature in Microbial Ecology
- Vol. 23 (1), 1-14
- https://doi.org/10.1007/bf00165903
Abstract
The nutritional responses of unattached and attached bacterial communities were studied in groundwater from 3 sampling depths, i.e., 830–841 m, 910–921 m, and 999–1,078 m, of the subvertical borehole KLX01 at the Laxemar study area in SE Sweden. The salinity profile of the groundwater in this borehole is homogeneous. There were negative redox potentials (Eh) in the waters (−220 to −270 mV) and they contained sulfide, hydrogen, and methane. Biofilm reactors with hydrophilic glass surfaces were connected to the flowing groundwaters from each of the 3 depths with flow rates of approximately 3 x 10−3 m sec−1 over 19 days. There were 0.15 to 0.68 × 105 unattached bacteria ml−1 groundwater and 0.94 to 1.2 × 105 attached bacteria cm−2 on the surfaces. The assimilations of 14CO2, 14C-formate, 1,2,3-3H-acetate, U-14C-lactate, U-14C-glucose, and L-4,5-3H-leucine by the communities were demonstrated with microautoradiographic and liquid scintillation counting techniques. There were significant assimilations of CO2 by all communities, except for the unattached bacteria at the 910–921 m depth, indicating in situ production of organic carbon from carbonate. Assimilation of formate was detected in two communities, indicating the presence of bacteria able to substitute CO2 with formate. Acetate, lactate, and glucose assimilations demonstrated the presence of heterotrophic bacteria. The assimilation of lactate by the attached bacteria dominated over acetate and glucose at all depths. Leucine was assimilated by 20 to 98% of the communities, which showed that major portions of the communities studied were viable. The results indicate that the attached communities at the 830–841 m and 910–921 m depths were in more metabolically active states than the unattached bacteria. Incubation in air compared with N2 indicated that portions of the studied communities were obligate anaerobes, as their ability to assimilate the added compounds was sensitive to oxygen. The results show that the use of several different compounds reduces the risk for false conclusions about the viability and the metabolic activity of the deep groundwater communities.Keywords
This publication has 25 references indexed in Scilit:
- Culture parameters regulating stalk formation and growth rate of Gallionella ferrugineaJournal of General Microbiology, 1990
- Aerobic metabolic potential of microbial populations indigenous to deep subsurface environmentsGeomicrobiology Journal, 1989
- Bacterial metabolism and the δ13C composition of ground water, Floridan aquifer system, South CarolinaGeology, 1988
- Microbial Ecology of the Terrestrial SubsurfaceAdvances in applied microbiology, 1988
- Autotrophic CO2 Fixation in Chemotrophic Anaerobic BacteriaPublished by Springer Nature ,1987
- CO2fixation in acetogenic bacteria: Variations on a themeFEMS Microbiology Letters, 1986
- Metal fixation by bacterial cell wallsCanadian Journal of Earth Sciences, 1985
- A New System for Ground Water MonitoringGround Water Monitoring & Remediation, 1984
- The occurrence and origin of methane in some groundwater flow systemsCanadian Journal of Earth Sciences, 1981
- Sulfate‐reducing and methanogenic bacteria from deep aquifers in montanaGeomicrobiology Journal, 1981