NC10 bacteria promoted methane oxidation coupled to chlorate reduction

The strictly anaerobic serum bottles were applied to investigate methane oxidation coupled to chlorate (ClO3-) reduction (MO-CR) without exogenous oxygen. 0.35 mM ClO(3)(-)was consumed within 20 days at the reduction rate of 17.50 mu M/d, over three times than that of ClO4-. Chlorite (ClO2-) was not detected throughout the experiment and the mass recovery of Cl(-)was over 89%. Isotope tracing results showed most of(13)CH(4)was oxided to CO2, and the electrons recovery reached to 77.6%. Small amounts of(13)CH(4)was consumed for DOC production probably through aerobic methane oxidation process, with oxygen generated from disproportionation reaction. InpMMO(key enzyme in aerobic oxidation of methane) inhibition tests, ClO(3)(-)reduction rate was slowed to 7. 0 mu mol/d by 2 mM C2H2, real-time quantitative PCR also showed the transcript abundance ofpMMOandCldwere significantly dropped at the later period of experiment, indicating that the O(2)disproportionated from ClO(2)(-)was utilized to active CH4. NC10 bacteriaCandidatus Methylomirabilis, related closely to oxygenic denitrifiersM. oxyfera, was detected in the system, and got enriched along with chlorate reduction. Several pieces of evidence supported that NC10 bacteria promoted CH(4)oxidation coupled to ClO(3)(-)reduction, these oxygenic denitrifiers may perform ClO(2)(-)disproportionation to produce O-2, and then oxidized methane intracellularly.