Post-Sampling Changes in Microbial Community Composition and Activity in a Subsurface Paleosol

Abstract

A B S T R A C TLaboratory storage of deep vadose zone sediments has previously resulted in an increase in the abundance of cultured microorganisms by as much as 10,000-fold, without concomitant increases in total microscopic counts. In the present study, factors contributing to the time-dependent stimulation of various microbiological parameters were examined during a 224 d post-sampling period, using a factorial-design experiment that partitioned the effects of storage time, sediment condition (intact blocks or homogenized) during storage, and O 2 concentration (0.5, 4.5, and 21%) during storage at 15°C. Stored samples were analyzed at selected intervals, to determine direct microscopic counts, viable biomass, lipid biomarker profiles, cultured aerobic heterotrophic microorganisms, and microbial activity. Time of storage prior to analysis of the samples was the most important factor affecting the microbiological response. Sediment condition influenced the stimu-

Field Investigation Report for Waste Management Area S-SX Volume 1 & 2 [SEC 1 Thru 6]

“…Additional support for this hypothesis was provided by Kiefi et al (1993) who observed bacterial cells, by direct microscopy, in the range of lo6 to lo7 cells/g in pristine Hanford formation sediments. Also, studies by our laboratory Brockman et al 1998) and others 'bd = below detection or less than 2.0 log colony forming units (CFU)/g. bsediments subjected to artificial recharge, contamination by past site activities ).…”

Microbial community response to petroleum hydrocarbon contamination in the unsaturated zone at the experimental field site V�rl�se, Denmark

“…After contamination of pristine soil with petroleum, an increase in microbial activity, but a decrease in diversity, is generally observed (see [8][9][10][11][12][13][14][15]). However, most studies with artificially polluted soils were performed in the laboratory, and significant effects on the activity and composition of the microbial communities in controls without contamination were also observed, as a result of the incubation process [10,22]. Thus, the transferability of long-term laboratory studies to the field situation is often questionable.…”

Exploration of deep intraterrestrial microbial life: current perspectives

“…For instance, the need for rapid initiation of analyses after sediment sample acquisition was demonstrated for measurements of in situ microbial properties [30]. Subsequently, the experience gained was used in studies of the environmental conditions under which microorganisms exist in deep continental hydrocarbon reservoirs.…”