Reversal of 2-bromoethanesulfonate inhibition of methanogenesis in Methanosarcina sp.

Abstract

2-Bromoethanesulfonate (BES) inhibition of methanogenesis from methanol by resting-cell suspensions or cell extracts of Methanosarcina was reversed by coenzyme M. BES inhibition of methylcoenzyme M methylreductase activity in cell-free extracts was reversed by methylcoenzyme M but not by coenzyme M. Methanol/coenzyme M methyltransferase activity was not inhibited by 10 μM BES. Inhibition of methylreductase by BES and 3-bromopropionate was competitive with methylcoenzyme M, but inhibition by 2-bromoethanol exhibited mixed kinetics. The K(i) values for the inhibitors in cell-free extracts were similar to the concentrations which inhibited intact cells. BES-resistant mutants of strain 227 were apparently permeability mutants because in vitro assays showed that mutant and parent strain methylreductases were equally sensitive to BES.