Survey of Microbial Populations in Buried‐Valley Aquifer Sediments from Northeastern Kansas

Abstract

Twenty‐two aseptically collected sediment core samples were obtained from below the water table (60 to 280 feet deep) at four pristine sites along a major buried‐valley aquifer system in northeastern Kansas. Samples were examined for total numbers of bacteria, viable aerobic bacteria, protozoa, and fungi. Contiguous samples were obtained in some transition zones of sediment texture or color in order to detect possible population shifts over small vertical distances related to changes in sediment characteristics. Total counts of bacteria varied between 106 and 108 per gram of dry sediment. Viable bacterial counts varied between 0 and 108 colony forming units per gram, usually being higher in sandy or gravelly sediments than in silty or clayey sediments. The relationship between sediment texture and microbial population density was confirmed statistically. Total numbers of bacteria correlated highly with variations in sediment sand and clay content. The population densities of viable bacteria and protozoa correlated moderately with these indicators of sediment texture. In some samples, populations of viable bacteria approached the total count of bacteria and the diversity of bacterial colony types appraoched that found in surface soil. Protozoa were found at low population densities in the coarser textured samples. The protozoa were similar to types commonly encountered in surface soil. No actinomycetes, fungi, or algae were detected in any samples.

Review: Microbial biocenoses in pristine aquifers and an assessment of investigative methods

“…There is often no significant difference between the unsaturated and saturated zone, only a slight decrease with depth. Higher numbers were usually found in coarse grained, highly permeable layers, while there was not always a clear correlation between OC and cell number (Balkwill and Ghiorse 1985;Bone and Balkwill 1988;Konopka and Turco 1991;Sinclair et al 1990). In groundwater from different types of aquifers, planktonic cell numbers often range between 10 4 and 10 6 cells mL −1 , about two orders of magnitude lower than the number of benthic cells.…”

“…cyclic adenosine monophosphate (cAMP)) in order to increase the cultivation efficiency for heterotrophic bacteria from aquatic (marine) environments (Bruns et al 2002). In some cases, however, the number of culturable counts was nearly equal to the number of direct visual counts, indicating that most cells were in an active state (Sinclair et al 1990). …”

Microbial biomass and activity in subsurface sediments from Vejen, Denmark

“…The ratio of active bacteria (CFU/AODC) ( Table 2) as well as the viable counts and the total number of bacteria (Fig. 2) are within the range of values reported from subsurface sediments [3,7,33,36]. The very small percentage of active bacteria indicates that a large part of the total amount of bacteria was inactive or unculturable, especially in the two glacial clay samples (20.4 and 27.5 robs).…”

“…Other investigators have also found the highest total number of bacteria (AODC) in samples with a high content of clay and silt [7] and in the clay and silt fraction of size-fractionated sediment [16]. In contrast, measurements of microbial population density (AODC, viable count) have shown positive correlations with sand content and moderate negative correlations with clay content in other subsurface systems [10,32,33]. We, Chapelle et al [7], and Harvey et al [16] enumerated bacteria on a filter, whereas the other investigators embedded the sediment sample in an agar smear.…”

“…Another approach has been to show correlations between different abiotic parameters and occurrence or activity of microbial populations. The density of microbial populations (AODC, viable counts) has been found to correlate with sediment texture in the subsurface [7,32,33]. In addition, microbial activity, estimated from mineralization of acetate, phenol, and hydroxybenzoate, correlated with the content of clay [5,10,17,24].…”