Homolytic carbon to phosphorus bond scission of some phosphonates catalyzed by bacterial carbon-phosphorus lyase

The production of volatile degradation products of phosphonates was monitored to investigate the mechanism involved in the biodegradation of propylphosphonic acid and phenylphosphonic acid byRhizobium sp MMM101a. The biodegradation of propylphosphonic acid gave rise to the production, in decreasing order, of propane, methane, ethane, 1-butene, propene, isobutene, butane and ethene. The formation of these degradation products was strongly reduced by adding catalase to the growing cultures indicating the involvement of peroxides in the biodegradation mechanism. OH⁰ radical scavengers did not reduce the rate of biodegradation, and therefore these radicals appear not to be involved. Addition of ascorbate, a known hydroxylating agent in biological systems, increased the amount of biodegradation products. The involvement of iron in the degradation was indicated and was optimal at a concentration of 950 µM. This suggests the involvement of a metalloenzyme involving iron and peroxide. The decomposition of phenylphosphonic acid yielded benzene and biphenyl. No phenol could be detected, again suggesting that OH⁰ radicals were not involved in the biodegradation. The presence of deuterated benzene did not result in the occurrence of biphenyl consisting of one nondeuterated and a deuterated ring, which is chemically more likely. It therefore appears that the degradation of the phosphonates occurs on a multicentered enzyme. The diversity of the products generated by this bacterium from phosphonates, many of them due to rearrangement of the carbon moiety of the substrate molecule, suggests an overall involvement of superoxide radicals in the homolytic carbon to phosphorus bond scission.     

Present dangers and future threats: some perverse incentives in the NHS reforms.

The NHS reforms have come to mean all things to all men (and women). Identifying a market oriented purchaser-provider split as the conceptual heart of the reforms is still, however, useful. There are important perverse incentives in and around the NHS that are associated with the reforms; furthermore, many reactions to the resulting problems are paradoxical and often counterproductive. Hitherto most criticism of the reforms from the health policy and management community (as opposed to the professions and the public) has been tactical rather than fundamental. There are serious problems for the NHS associated both with the NHS market and with current, often tacit, strategies for the future of the service.