A Model Framework to Describe Growth-Linked Biodegradation of Trace-Level Pollutants in the Presence of Coincidental Carbon Substrates and Microbes

Abstract

Pollutants such as pesticides and their degradation products occur ubiquitously in natural aquatic environments at trace concentrations (μg L–1 and lower). Microbial biodegradation processes have long been known to contribute to the attenuation of pesticides in contaminated environments. However, challenges remain in developing engineered remediation strategies for pesticide-contaminated environments because the fundamental processes that regulate growth-linked biodegradation of pesticides in natural environments remain poorly understood. In this research, we developed a model framework to describe growth-linked biodegradation of pesticides at trace concentrations. We used experimental data reported in the literature or novel simulations to explore three fundamental kinetic processes in isolation. We then combine these kinetic processes into a unified model framework. The three kinetic processes described were: the growth-linked biodegradation of micropollutant at environmentally relevant concentrations; the effect of coincidental assimilable organic carbon substrates; and the effect of coincidental microbes that compete for assimilable organic carbon substrates. We used Monod kinetic models to describe substrate utilization and microbial growth rates for specific pesticide and degrader pairs. We then extended the model to include terms for utilization of assimilable organic carbon substrates by the specific degrader and coincidental microbes, growth on assimilable organic carbon substrates by the specific degrader and coincidental microbes, and endogenous metabolism. The proposed model framework enables interpretation and description of a range of experimental observations on micropollutant biodegradation. The model provides a useful tool to identify environmental conditions with respect to the occurrence of assimilable organic carbon and coincidental microbes that may result in enhanced or reduced micropollutant biodegradation.

Biocarriers Improve Bioaugmentation Efficiency of a Rapid Sand Filter for the Treatment of 2,6-Dichlorobenzamide-Contaminated Drinking Water

“…By using the conversion factor of Van der Kooij, cell growth was converted to AOC available to MSH1 and was estimated at 20 ± 4 and 22 ± 4 μg/L for suspended and immobilized cells, respectively. On average, AOC in groundwater is estimated at 100 μg/L AOC. , AOC in groundwater and the competition of MSH1 for this AOC with the established sand filter community is a key limitation for steady-state MSH1 biomass in the reactors and BAM-degrading activity . As such, the carriers used in this study can be modified by adding dedicated amounts of AOC to the alginate solution when producing the immobilized MSH1 carriers.…”

“…5,32 AOC in groundwater and the competition of MSH1 for this AOC with the established sand filter community is a key limitation for steady-state MSH1 biomass in the reactors and BAM-degrading activity. 38 As such, the carriers used in this study can be modified by adding dedicated amounts of AOC to the alginate solution when producing the immobilized MSH1 carriers. The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.est.6b05027.…”

Implications of microbial adaptation for the assessment of environmental persistence of chemicals

“…Microbial biodegradation of organic chemicals may occur either via growth-linked degradation or via co-metabolism. Growth-linked biodegradation, also called metabolic degradation, is the process where microorganism use the chemical as sole carbon and free energy source (Liu, Helbling, Kohler, & Smets, 2014;Tran, Urase, Ngo, Hu, & Ong, 2013). Co-metabolic degradation, on the other hand, is the process where the chemical is metabolized in cells that grow on another type of carbon and free energy source, usually a compound with biochemical features that resemble the chemical (Kassotaki, Buttiglieri, Ferrando-Climent, Rodriguez-Roda, & Pijuan, 2016;Peng, Qu, Luo, & Jia, 2014;Tran et al, 2013).…”

Organic Carbon Amendments for Enhanced Biological Attenuation of Trace Organic Contaminants in Biochar-Amended Stormwater Biofilters

“…Atrazine and prometon, in contrast, were biodegraded only in compost microcosms following a 30-day lag time. Depletion of preferential carbon substrates may have caused this lag time, subsequently allowing TOrC biodegradation due to adaptive expression of TOrC-degrading enzymes , or reduced substrate–substrate inhibitions . The greater aromatic character of the compost DOC may have contributed to this behavior, as these more complex carbon substrates may have been more slowly utilized and hence still present upon TOrC exposure.…”

“…Depletion of preferential carbon substrates may have caused this lag time, subsequently allowing TOrC biodegradation due to adaptive expression of TOrC-degrading enzymes 40,41 or reduced substrate−substrate inhibitions. 42 The greater aromatic character of the compost DOC may have contributed to this behavior, as these more complex carbon substrates may have been more slowly utilized and hence still present upon TOrC exposure. TCPP and TCEP biodegradation in the outlier microcosm was particularly abrupt after the 30-day lag time, potentially due to the sudden activity of specialist bacteria.…”