Natural inactivation of Escherichia coli in anoxic and reduced groundwater

Journal of Applied Microbiology




Inactivation rates of E. coli in groundwater have most often been determined in aerobic and oxidized systems. This study examined E. coli inactivation rates in anaerobic and extremely reduced groundwater systems that have been identified as recharge zones.

Methods and Results

Groundwater from six artesian wells was diverted to above ground, flow through mesocosms that contained laboratory grown E. coli in diffusion chambers. All groundwater was anaerobic and extremely reduced (ORP < -300 mV). Cells were plated onto mTEC agar during 21 day incubation periods. All data fit a bi-phasic inactivation model, with > 95% of the E. coli population being inactivated < 11.0 hrs (mean k = 0.488± 0.188 h−1).


The groundwater geochemical conditions enhanced the inactivation of E. coli to rates approximately 21-fold greater than previously published inactivation rate in groundwater (mean k= 0.023 ± 0.030 h−1). Also, mTEC agar inhibits E. coli growth following exposure to anaerobic and reduced groundwater.

Significance and Impact of the Study

Aquifer recharge zones with geochemical characteristics observed in this study complement above ground engineered processes (e.g., filtration, disinfection), while increasing the overall indicator microorganism log-reduction rate of a facility.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Natural inactivation of Escherichia coli in anoxic and reduced groundwater
Series title Journal of Applied Microbiology
DOI 10.1111/jam.13126
Volume 120
Issue 6
Year Published 2016
Language English
Publisher Wiley
Contributing office(s) St. Petersburg Coastal and Marine Science Center
Description 12 p.
First page 1739
Last page 1750
Online Only (Y/N) N
Additional Online Files (Y/N) N