Effect of nickel, cobalt and iron on methanogenesis from methanol and co-metabolic conversion of 1,2-dichloroethene (DCE) by Methanosarcina barkeri.

Methanogens are responsible for the last step in anaerobic digestion (AD), in which methane (a biofuel) is produced. Some methanogens can co-metabolize chlorinated pollutants, contributing for their removal during AD. Methanogenic cofactors involved in co-metabolic reductive dechlorination, such as F430 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 co-metabolic 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 muM of Fe(3+) showed the highest final concentration of VC (5x higher than in controls without Fe(3+) ), but also in assays with 5.5 muM of Co(2+) and 5 muM of Ni(2+) VC formation was improved (3.5-4x 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. This article is protected by copyright. All rights reserved.