Editor: Alfons Stams
Effects of hydrogen and acetate on benzene mineralisation under sulphate-reducing conditions
Article first published online: 20 APR 2011
© 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved
FEMS Microbiology Ecology
Volume 77, Issue 2, pages 238–247, August 2011
How to Cite
Rakoczy, J., Schleinitz, K. M., Müller, N., Richnow, H. H. and Vogt, C. (2011), Effects of hydrogen and acetate on benzene mineralisation under sulphate-reducing conditions. FEMS Microbiology Ecology, 77: 238–247. doi: 10.1111/j.1574-6941.2011.01101.x
- Issue published online: 11 JUL 2011
- Article first published online: 20 APR 2011
- Accepted manuscript online: 30 MAR 2011 09:42AM EST
- Received 22 July 2010; revised 25 March 2011; accepted 25 March 2011., Final version published online 20 April 2011.
- anaerobic benzene mineralisation;
- interspecies metabolite transfer;
Syntrophic mineralisation of benzene, as recently proposed for a sulphate-reducing enrichment culture, was tested in product inhibition experiments with acetate and hydrogen, both putative intermediates of anaerobic benzene fermentation. Using [13C6]-benzene enabled tracking the inhibition of benzene mineralisation sensitively by analysis of 13CO2. In noninhibited cultures, hydrogen was detected at partial pressures of 2.4 × 10−6± 1.5 × 10−6 atm. Acetate was detected at concentrations of 17 ± 2 μM. Spiking with 0.1 atm hydrogen produced a transient inhibitory effect on 13CO2 formation. In cultures spiked with higher amounts of hydrogen, benzene mineralisation did not restart after hydrogen consumption, possibly due to the toxic effects of the sulphide produced. An inhibitory effect was also observed when acetate was added to the cultures (0.3, 3.5 and 30 mM). Benzene mineralisation resumed after acetate was degraded to concentrations found in noninhibited cultures, indicating that acetate is another key intermediate in anaerobic benzene mineralisation. Although benzene mineralisation by a single sulphate reducer cannot be ruled out, our results strongly point to an involvement of syntrophic interactions in the process. Thermodynamic calculations revealed that, under in situ conditions, benzene fermentation to hydrogen and acetate yielded a free energy change of ΔG′=−83.1 ± 5.6 kJ mol−1. Benzene mineralisation ceased when ΔG′ values declined below −61.3 ± 5.3 kJ mol−1 in the presence of acetate, indicating that ATP-consuming reactions are involved in the pathway.