[Isolation of heterotrophic nitrifiers/aerobic denitrifiers and their roles in N2O production for different incubations].
Soil microorganisms are important sources of N2O for the atmosphere. Peak emissions of N2O are often observed after wetting of soil. The simultaneous heterotrophic nitrifying and aerobic denitrifying bacteria with respect to N2O emission were studied to obtain more information about the microbiologcal aspects of peak emissions. Using acetamide as the C and N source, two strains of nitrifying and denitrifying bacteria were isolated, coded as XM1 and HX2,respectively. XM1 strain was Gram-negative chain-like bacilli, and the HX2 was Gram-negative cocci. In enrichment culture, N2O production of HX2 was 76 times more than XM1. Two strains could grow with glucose, mannitol or sodium tartrate as sole carbon source, respectively. They could nitrify with sodium nitrate or denitrify with ammonium sulfate as unique nitrogen source, and produce intermediate product nitrite. XM1 strain growth velocity and nitrite formation were obviously higher than HX2. The phylogentic analysis based on partial 16S rDNA showed that two isolated strains were the closest relative of Pseudomonas sp.99% sequence similarity. Under different WFPS (water-filled-pore-space) conditions, the aerobic autoclaved soil incubation trial showed that, HX2 strain was suitable for growing in 30% WFPS, and N2O production was (36.01 +/- 2.48) ng/g which was 1.9 times than that in 60% WFPS. But XM1 was suitable for growing in 60% WFPS and almost had no N2O production. To investigate the nitrifying and denitrifying mechanisms of heterotrophic nitrifiers/aerobic denitrifiers should be useful for mastering the mitigation way of soil N2O emission in future.
Jiang
Jing-Yan
JY
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China. lilacjjy@njau.edu.cn
Hu
Zheng-Hua
ZH
Huang
Yao
Y
D000332:Aerobiosis; D046508:Culture Techniques; D006090:Gram-Negative Bacteria / Q000302:isolation & purification* / Q000378:metabolism*; D009609:Nitrous Oxide / Q000737:chemistry / Q000378:metabolism*; D011549:Pseudomonas / Q000302:isolation & purification / Q000378:metabolism; D012988:Soil Microbiology
D009609:Nitrous Oxide