Effect of nickel, cobalt, and iron on methanogenesis from methanol and cometabolic conversion of 1,2‐dichloroethene by Methanosarcina barkeri

Abstract

Methanogens are responsible for the last step in anaerobic digestion (AD), in which methane (a biofuel) is produced. Some methanogens can cometabolize chlorinated pollutants, contributing for their removal during AD. Methanogenic cofactors involved in cometabolic reductive dechlorination, such as F 430 and cobalamin, contain metal ions (nickel, cobalt, iron) in their structure. We hypothesized that the supplementation of trace metals could improve methane production and the cometabolic dechlorination of 1,2-dichloroethene (DCE) by pure cultures of Methanosarcina barkeri. Nickel, cobalt, and iron were added to cultures of M. barkeri growing on methanol and methanol plus DCE. Metal amendment improved DCE dechlorination to vinyl chloride (VC): assays with 20 µM of Fe 3+ showed the highest final concentration of VC (5× higher than in controls without Fe 3+), but also in assays with 5.5 µM of Co 2+ and 5 µM of Ni 2+ VC formation was improved (3.5-4× higher than in controls without the respective metals). Dosing of metals could be useful to improve anaerobic removal of chlorinated compounds, and more importantly decrease the detrimental effect of DCE on methane production in anaerobic digesters. C

Biofuels Production from Renewable Resources

“…Since methanogens are known to be cometabolizers of chlorinated pollutants, Paulo et al. [5] focused their work on the effect of nickel, cobalt, and iron on the growth of Methanosarcina barkeri . The data show how metal addition improves 1,2‐dichloroethene dechlorination to vinyl chloride, indicating that metal ions can be a limiting factor in methanogenesis and dechlorination.…”

Effect of Sub-Stoichiometric Fe(III) Amounts on LCFA Degradation by Methanogenic Communities

“…If methane production is intended, Fe(III) should be dosed to avoid out-competition of methanogens by IRB [ 21 ]. Moreover, amorphous Fe(OH) 3 was shown to directly inhibit the activity of Methanospirillum hungatei and Methanosaeta concilii grown in pure culture [ 22 ], and some methanogens (e.g., Methanosarcina barkeri ) also have the ability to reduce Fe(III), which may contribute to methanogenesis inhibition [ 22 , 23 ]. Bond and Lovley [ 24 ] reported that the inhibition of methane production in Fe(III) oxide-containing sediments may result, at least in part, from methanogens diverting electrons to Fe(III) reduction.…”