Effects on microbial activity by extraction of indigenous cells from soil slurries

Abstract

Possible effects on the physiological activity and culturability of soil microorganisms by different soil dispersion procedures, and effects on activity caused by extracting bacteria from soil, were investigated. There was no apparent difference in cfu's with dispersion of a silty loam soil and a loamy sand soil with pyrophosphate as compared to dispersion in NaCl. Substrate‐induced respiration was reduced in the silty loam soil, and methanol oxidation was reduced in the loamy sand soil with dispersion in pyrophosphate, and the soil pH was irreversibly increased by the treatment. Extracted bacterial fractions had lower numbers of culturable cells as percentage of the total number of bacteria in each fraction, lower respiration rates and no methanol oxidation activity as compared to the soil slurry both before and after extraction. The physiological activity was apparently not affected by the number of cells extracted. This indicates that the increased extraction rate of indigenous soil bacteria obtained by effective disruption of aggregates and detachment of cells from surfaces, only results in increased extraction of cells that have been physiologically changed as a result of the extraction process.

Evidence for syntrophic butyrate metabolism under sulfate-reducing conditions in a hydrocarbon-contaminated aquifer

“…MPN analysis was not definitive in determining the predominant butyrate degrader in contaminated sediments as only very low numbers of butyrate degraders were detected regardless of the cultivation condition. The low numbers detected could have been due to the inefficiency of the pyrophosphate treatment in removing attached microorganisms from the sediment or the difficulty in culturing microorganisms responsible for butyrate degradation (Lindahl et al , 1996; Schink, 1997; Hansen et al , 1999; Hatamoto et al , 2008). Identical approaches detected about 10 6 acetoclastic methanogens g −1 from the same sediments (Struchtemeyer et al , 2005).…”

Size fractionation of bacterial functional diversity within soils

“…Therefore, the resulting inoculum may not represent the majority of the indigenous soil bacteria that firmly attach to surfaces or are found in aggregates (Lindahl et al, 1996). This has a direct effect on the substrate utilization patterns obtained on BIOLOG ® plates, since moribund or physiologically-inactive cells may be among these easily-detachable cells (Riis et al, 1998), and the metabolic potential of many indigenous soil bacteria more firmly attached to soil particles may not be included in the analysis.…”