Anaerobic oxidation of aldehydes to carboxylic acids under hydrothermal conditions

Efficient anaerobic oxidation of aldehydes using iron(iii) nitrate under hydrothermal conditions is reported.

KINETIC ISOTOPIC EFFECT: STATIC RAYLEIGH EQUATION AND BASIC DYNAMIC ISOTOPE EQUATION FOR THE SUBSTRATE IN THE DESCRIPTION OF NITRITE-DEPENDENT ANAEROBIC OXIDATION OF METHANE

The article analyzes the results of modeling the dynamics of nitrite-dependent methane oxidation (N-DAMO) by Methylomirabilis oxyfera microorganisms using the standard isotope dynamic equations. Without specifying a specific function of the rate of the process, the traditional static Rayleigh equation is derived from the basic dynamic isotope equation. Thus, the equation of the 1st order in terms of the substrate is only a special case in the derivation of the Rayleigh equation. It was shown that the dominant fractionation of carbon isotopes occurs in the process of the microbiological reaction of anaerobic oxidation of methane by nitrite, and not in the physical process of mass transfer of dissolved methane into the gas phase. In contrast to the static Rayleigh equation, the dynamic description of the process of fractionation of stable isotopes is important when describing the parallel transformations of the substrate.

Iron-Coupled Anaerobic Oxidation of Methane in Marine Sediments: A Review

Anaerobic oxidation of methane (AOM) is one of the major processes of oxidizing methane in marine sediments. Up to now, extensive studies about AOM coupled to sulfate reduction have been conducted because SO42− is the most abundant electron acceptor in seawater and shallow marine sediments. However, other terminal electron acceptors of AOM, such as NO3−, NO2−, Mn(IV), Fe(III), are more energetically favorable than SO42−. Iron oxides, part of the major components in deep marine sediments, might play a significant role as an electron acceptor in the AOM process, mainly below the sulfate–methane interface, mediated by physiologically related microorganisms. Iron-coupled AOM is possibly the dominant non-sulfate-dependent AOM process to consume methane in marine ecosystems. In this review, the conditions for iron-coupled AOM are summarized, and the forms of iron oxides as electron acceptors and the microbial mechanisms are discussed.