The interaction of organic carbon substrates with microorganisms and mineral phases is a key factor regulating the fate of organic matter and its conversion to CO2. While carbon substrates can be transformed into biomass or mineralized to CO2 through microbial metabolism, mineral phases can stabilize organic compounds through sorption processes or induce their oxidation through redox reactions. Manganese oxides (MnOx) are among the strongest natural oxidants in soils, which are through to oxidize organic substrates through successive decarboxylation steps, leading to the final release of CO2 (Wang & Stone, 2006). From the Mn side, these reactions can induce the accumulation of Mn(III) in the oxide, and/or dissolution to Mn(II). The strong reactivity of MnOx may, therefore, compete with microbial activity for the available carbon sources. The kinetics and mechanism of glucose oxidation by MnOx were studied in the presence and absence of the heterotrophic organism Pseudomonas putida. Reaction products were monitored over 1 week to compile mass and electron balances. The extent of reductive dissolution, as measured by Mn(II)aq, increased over time and with decreasing pH. However, independently of pH and in both biotic and abiotic conditions, reductive dissolution was precedeed by a rapid increase in the Mn(III) content in the solid phase (i.e. up to 40%Mn(III)). In abiotic systems, formic acid was the main oxdation product and no loss of total organic carbon (TOC) was observed, indicating incomplete mineralization. In bacteria-only experiments, the oxidation of glucose in the absence of δ-MnO2 led to a complete loss of TOC. However, the decrease in TOC was limited in the presence of δ-MnO2, suggesting that oxides may compete for organic substrates with bacteria and alter the pool of available carbon sources for microbial activity.

Fate of bioavailable carbon sources in presence of manganese oxides

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.