An unusual strategy for the anoxic biodegradation of phthalate

International audienceIn the past two decades, the study of oxygen-independent degradation of widely abundant aromatic compounds in anaerobic bacteria has revealed numerous unprecedented enzymatic principles. Surprisingly, the organisms, metabolites and enzymes involved in the degradation of o-phthalate (1,2-dicarboxybenzene), mainly derived from phthalate esters that are annually produced at the million ton scale, are sparsely known. Here, we demonstrate a previously unknown capacity of complete phthalate degradation in established aromatic compound-degrading, denitrifying model organisms of the genera Thauera, Azoarcus and ‘Aromatoleum’. Differential proteome analyses revealed phthalate-induced gene clusters involved in uptake and conversion of phthalate to the central intermediate benzoyl-CoA. Enzyme assays provided in vitro evidence for the formation of phthaloyl-CoA by a succinyl-CoA- and phthalate-specific CoA transferase, which is essential for the subsequent oxygen-sensitive decarboxylation to benzoyl-CoA. The extreme instability of the phthaloyl-CoA intermediate requires highly balanced CoA transferase and decarboxylase activities to avoid its cellular accumulation. Phylogenetic analysis revealed phthaloyl-CoA decarboxylase as a novel member of the UbiD-like, (de)carboxylase enzyme family. Homologs of the encoding gene form a phylogenetic cluster and are found in soil, freshwater and marine bacteria; an ongoing global distribution of a possibly only recently evolved degradation pathway is suggested

Reversible Deactivation Radical Polymerization of Vinyl Chloride

Poly(vinyl chloride) (PVC) is one of the higher consumed polymers (more than 40 million tons per year) and can only be prepared on an industrial scale by free-radical polymerization (FRP). Several intrinsic limitations of FRP have triggered interest in synthesizing this polymer by reversible deactivation radical polymerization (RDRP) methods. Despite the many achievements that have been made, the RDRP of nonactivated monomers, such as vinyl chloride (VC), presents several challenges to the scientific community. Several features of VC make its control by RDRP techniques particularly difficult. The most recent developments on RDRP of VC are critically discussed