Investigations into the number of respiring bacteria in groundwater from sandy and gravelly deposits

Abstract

Samples were collected from organically polluted and unpolluted groundwater of sandy and gravelly deposits. After filtration onto polycarbonate filters (0.2μm pore size) the number of respiring bacteria was recorded by microscopically counting cells containing red INT-formazan spots, which characterize respiring bacteria. The total number of bacteria was simultaneously recorded by epifluorescence microscopy after staining with acridine orange. The number of respiring bacteria in the groundwater samples (55-490×10(3)/cm(3)) is within the range of values for other aquatic biotopes, but as the total number of bacteria in groundwater was usually higher, the proportion of respiring groundwater bacteria (0.66-7. 4%) was lower. Mainly larger bacteria, rods, and bacteria on particles could be identified as being active, whereas hardly any respiratory activity could be detected among small cocci and free interstitial bacteria. If the supply of dissolved organic matter (DOM) is adequate, the biomass of respiring bacteria correlates well with oxygen concentration, but there is no direct correlation between DOM concentration in groundwater and active bacterial biomass. Nor could any relationship be observed between the biomass of total and respiring bacteria, or between the quantity of respiring bacteria and heterotrophic bacterial activity.

Comparison of solutes, nutrients, and bacteria inputs from two types of groundwater to the Rh�ne river during an artificial drought

“…The present study demonstrates that a part of the DOC (47%) is in fact biodegradable and 8 .8% of the interstitial bacteria that drifted into the River Rhone were active . This last value is similar to those observed by Marxsen (1988) in groundwater (from 0 .66 to 7 .4%) using the INT formazan staining method . The increase in DOC, BDOC, and bacterial contents in groundwater on the second day of the experiment (Fig .…”

Spatiotemporal distribution of microbial communities in a coastal, sandy aquifer system (Doñana, SW Spain)

“…Short rod‐shaped bacteria have some advantages over large rod‐shaped and filamentous bacteria for transport through sandy sediments (Harvey et al ., 1984). Data in this study confirm previous ones (Velasco et al ., 2008; in press) and demonstrate that mean bacterial abundance observed in this aquifer system was, at least, one order of magnitude higher than that found in other sedimentary and relatively similar aquifer ecosystems (Harvey et al ., 1984; Kölbel‐Boelke et al ., 1988; Marxsen, 1988; Hirsch & Rades‐Rohkohl, 1990; Hazen et al ., 1991; Alfreider et al ., 1997; Griebler et al ., 2002). Groundwater mean bacterial abundance found in this study was also higher than planktonic bacterial densities found in granite (Eydal & Pedersen, 2007) or rock aquifer systems (Lehman et al ., 2004).…”

“…Microbial ecology studies of sedimentary, relatively shallow aquifer systems are relatively abundant (Marxsen, 1988; Alfreider et al ., 1997; Martino et al ., 1998; Griebler et al ., 2002; Velasco et al ., 2008; in press), but very few exist with large spatial and temporal scales. Some of these studies have shown aquifers as more stable ecosystems, with less spatiotemporal variation in their ecological processes, than other aquatic systems.…”

Bacteria associated with deep, alkaline, anaerobic groundwaters in Southeast Washington

“…Bulk water samples would contain predominantly planktonic bacteria, while sessile bacteria, which are occasionally sloughed Off, would be vastly outnumbered. Studies in other aquifers have shown that more than 90% of the microorganisms were attached to soild materials and that the morphology of attached cells was different than that of free-floating cells [15]. With the sand-trap method, however, the infrequent sloughed-off sessile cells would have an opportunity to re-attach to an uncolonized surface and form a new biofilm, hopefully similar to in situ biofilms.…”