Microbial growth and biofilm formation in geologic media is detected with complex conductivity measurements

Abstract

Complex conductivity measurements (0.1–1000 Hz) were obtained from biostimulated sand‐packed columns to investigate the effect of microbial growth and biofilm formation on the electrical properties of porous media. Microbial growth was verified by direct microbial counts, pH measurements, and environmental scanning electron microscope imaging. Peaks in imaginary (interfacial) conductivity in the biostimulated columns were coincident with peaks in the microbial cell concentrations extracted from sands. However, the real conductivity component showed no discernible relationship to microbial cell concentration. We suggest that the observed dynamic changes in the imaginary conductivity (σ″) arise from the growth and attachment of microbial cells and biofilms to sand surfaces. We conclude that complex conductivity techniques, specifically imaginary conductivity measurements are a proxy indicator for microbial growth and biofilm formation in porous media. Our results have implications for microbial enhanced oil recovery, CO2 sequestration, bioremediation, and astrobiology studies.

Geophysical Monitoring of Coupled Microbial and Geochemical Processes During Stimulated Subsurface Bioremediation

“…The elevated phase shift in the Although we have interpreted the lab and field phase anomalies within the context of an electrode polarization IP mechanism, we cannot completely discount the contribution of other factors in generating the anomalies, such as the growth and accumulation of planktonic and mineral-affixed biomass during acetate amendment. As noted, other studies (7,9,10) have demonstrated the role that cellular components can play in generating IP phase anomalies; however, the magnitude of the phase increase associated with biomass accumulation in these studies has generally been modest (<1-2 mrad). In contrast, studies of the temporal phase behavior accompanying biogenic mineral precipitation (11,12,18,19) have reported phase anomalies more than one order of magnitude larger than those involving cells alone.…”

Spectral induced polarization signatures of abiotic FeS precipitation

“…Previous experiments showed that SIP responses resulting from biomineralization processes ͑Ntarlagiannis et al, 2005a; Williams et al, 2005;Slater et al, 2007;Personna et al, 2008͒ are significantly higher than SIP responses resulting from microbial activity in the absence of metallic mineral precipitation ͑Abdel Aal et al, 2004;Abdel Aal et al, 2006;Davis et al, 2006͒. Based on such previous experience, we expected that the precipitation of metallic minerals, regardless of the driving processes, would lead to substantial SIP responses.…”

“…Traditionally, geophysical methods have been employed to image physical properties of the subsurface, and only recently have geophysical responses been linked indirectly to microbial activity ͑Atekwana et Atekwana and Slater, 2009͒. The need to more precisely correlate the effects of mineral surfaces, microbes, and the products of microbial activity with common geophysical measurements has led to an increasing number of laboratory studies ͑Ntarlagiannis et al, 2005a; Williams et al, 2005;Davis et al, 2006;Slater et al, 2007;Personna et al, 2008;Abdel Aal et al, 2009͒ and initial field studies designed to validate upscaling of the approach ͑Williams et al, 2009͒. One of the most successful methods is the SIP technique.…”

“…The SIP ͑or complex-conductivity͒ method appears to be sensitive to ͑1͒ the presence of microbial cells ͑Ntarlagiannis et al, 2005b͒, ͑2͒ biofilm formation ͑Davis et al, 2006͒, and ͑3͒ microbialinduced sulfide mineral precipitation ͑Ntarlagiannis et al, 2005a; Williams et al, 2005;Slater et al, 2007;Personna et al, 2008͒. In the absence of metallic minerals, the SIP phase responses attributed to microbial cells and biofilm formation are small ͑1.5-mrad phaseshift maximum͒, and they require meticulous instrument calibration and careful measurement protocol ͑Ntarlagiannis et al, 2005b; Davis et al, 2006͒. In contrast, the precipitation of metallic minerals, including metal sulfides, generates significantly larger SIP responses, at least an order of magnitude higher ͑15-mrad phase shift͒, yielding anomalies that are easier to detect and monitor ͑Ntarlagiannis et al, 2005a;Williams et al, 2005;Slater et al, 2007;Personna et al, 2008͒.…”

Laboratory study of spectral induced polarization responses of magnetite — Fe2+ redox reactions in porous media

“…SIP phase responses have been attributed to several different types of polarization phenomena including those associated with microbial cells and biofilms (Davis et al, 2006), non conductive minerals such as silica Zhang et al, 2012), and (semi)conductive particles such as sulfides Page 6 of 31 Geophysics Manuscript, Accepted Pending: For Review Not Production (Ntarlagiannis et al, , 2010a(Ntarlagiannis et al, , 2010b, magnetite and Fe(0) particles . Microbes and biofilms produce relatively small phase responses of typically <2 mrad (Ntarlagiannis and Ferguson, 2009).…”