Improvement of the trace metal composition of medium for nitrite-dependent anaerobic methane oxidation bacteria: Iron (II) and copper (II) make a difference.
Nitrite-dependent anaerobic methane oxidation (n-damo) is a potential bioprocess for treating nitrogen-containing wastewater. This process uses methane, an inexpensive and nontoxic end-product of anaerobic digestion, as an external electron donor. However, the low turnover rate and slow growth rate of n-damo functional bacteria limit the practical application of this process. In the present study, the short- and long-term effects of variations in trace metal concentrations on n-damo bacteria were investigated, and the concentrations of trace metal elements of medium were improved. The results were subsequently verified by a group of long-term inoculations (90 days) and were applied in a sequencing batch reactor (SBR) (84 days). The results indicated that iron (Fe(II)) and copper (Cu(II)) (20 and 10 μmol L(-1), respectively) significantly stimulated the activity and the growth of n-damo bacteria, whereas other trace metal elements, including zinc (Zn), molybdenum (Mo), cobalt (Co), manganese (Mn), and nickel (Ni), had no significant effect on n-damo bacteria in the tested concentration ranges. Interestingly, fluorescence in situ hybridization (FISH) showed that a large number of dense, large aggregates (10-50 μm) of n-damo bacteria were formed by cell adhesion in the SBR reactor after using the improved medium, and to our knowledge this is the first discovery of large aggregates of n-damo bacteria.
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Zhanfei
Z
He
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Sha
S
Geng
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Yawei
Y
Pan
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Chaoyang
C
Cai
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Jiaqi
J
Wang
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Liqiao
L
Wang
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Shuai
S
Liu
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Ping
P
Zheng
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China.
Xinhua
X
Xu
Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China. Electronic address: blhu@zju.edu.cn.
Baolan
B
Hu
D000693:Anaerobiosis; D019149:Bioreactors; D003300:Copper / Q000378:metabolism*; D017404:In Situ Hybridization, Fluorescence; D007501:Iron / Q000378:metabolism*; D008670:Metals / Q000378:metabolism*; D008772:Methylococcaceae / Q000378:metabolism*; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater
D003300:Copper; D007501:Iron; D008670:Metals; D062065:Wastewater
Biological nitrogen removal; Medium improvement; Nitrite-dependent anaerobic methane oxidation (n-damo); Transition metal