Ammonium-dependent regulation of aerobic methane-consuming bacteria in landfill cover soil by leachate irrigation.
The impacts of landfill leachate irrigation on methane oxidation activities and methane-consuming bacteria populations were studied by incubation of landfill cover soils with leachate and (NH4)2SO4 solution at different ammonium concentrations. The community structures and abundances of methane-oxidizing bacteria (MOB) and ammonia-oxidizing bacteria (AOB) were examined by PCR-DGGE and real-time PCR. Compared with the pure (NH4)2SO4 solution, leachate addition was found to have a positive effect on methane oxidation activity. In terms of the irrigation amount, ammonium in leachate was responsible for the actual inhibition of leachate. The extent of inhibitory effect mainly depended on its ammonium concentration. The suppression of the predominant methane-consuming bacteria, type I MOB, was responsible for the decreased methane oxidation activity by ammonium inhibition. Methane-consuming bacteria responded diversely in abundance to ammonium. The abundance of type I MOB decreased by fivefold; type II MOB showed stimulation response of fivefold magnification upon the first addition but lessened to be lower than the original level after the second addition; the amount of AOB was stimulated to increase for 20-30 times gradually. Accumulated nitrate from nitrification strengthened the ammonium inhibition on type I and type II MOB, as a result, repetitive irrigation was unfavorable for methane oxidation.
State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. solidwaste@tongji.edu.cn
Fan
F
Lü
Pinjing
P
He
Min
M
Guo
Na
N
Yang
Liming
L
Shao
D000332:Aerobiosis / Q000187:drug effects; D057914:Agricultural Irrigation; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism*; D001673:Biodegradation, Environmental / Q000187:drug effects; D044822:Biodiversity; D004275:DNA, Ribosomal / Q000235:genetics; D058645:Denaturing Gradient Gel Electrophoresis; D018628:Gene Dosage / Q000235:genetics; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008697:Methane / Q000378:metabolism*; D009566:Nitrates / Q000032:analysis; D017672:Nitrogen Compounds; D010084:Oxidation-Reduction / Q000187:drug effects; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D012987:Soil / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000494:pharmacology*
D004275:DNA, Ribosomal; D009566:Nitrates; D017672:Nitrogen Compounds; D000644:Quaternary Ammonium Compounds; D012987:Soil; D014874:Water Pollutants, Chemical; D008697:Methane