在氮的生物地球化学循环中,N2O还原酶将一氧化二氮(N2O)还原为N2,由nosZ基因编码,是消耗N2O的唯一生物途径。在这项研究中,我们成功地从污水处理厂污泥中分离出一株反硝化反硝化副球菌R-1。该菌株具有很强的N2O还原能力,在确定的培养基中厌氧条件下,平均N2O还原率为5.10±0.11×10-9µmol·h-1·cell-1。当N2O作为唯一的电子受体时,这种减少伴随着乙酸盐的化学计量消耗,这种减少可以产生支持微生物生长的能量。表明微生物N2O还原与能量产生过程有关。基因组分析显示,编码脱氮假单胞菌R-1N2O还原酶的基因簇由nosR组成,nosZ,nosD,nosF,nosY,nosL,和nosz,与进化枝I中的其他菌株相同。呼吸抑制剂测试表明,N2O还原的电子传递途径不同于传统的有氧呼吸电子传递链。Cu2+,银纳米粒子,O2和酸性条件下可以强烈抑制还原,而NO3-或NH4+可以促进它。这些发现表明,反硝化假单胞菌R-1的模块化N2O还原与电子传输和能量守恒有关,异化N2O还原是微生物厌氧呼吸的一种形式。
目的:一氧化二氮(N2O)是一种强效的温室气体,是臭氧层破坏的贡献者,在过去的一个世纪中,由于人类活动,大气中的N2O稳步增长。N2O从固定N中的释放几乎完全受微生物N2O还原酶活性的控制。这里,我们研究了通过将各种电子供体的氧化与N2O还原偶联来获得反硝化副球菌R-1生长能量的能力。反硝化微生物的模块化N2O还原过程不仅可以消耗自身产生的N2O,而且可以在合适的条件下消耗生物或非生物途径产生的外部N2O。这对于控制N2O从生态系统释放到大气中至关重要。
In the nitrogen biogeochemical cycle, the reduction of nitrous oxide (N2O) to N2 by N2O reductase, which is encoded by nosZ gene, is the only biological pathway for N2O consumption. In this study, we successfully isolated a strain of denitrifying Paracoccus denitrificans R-1 from sewage treatment plant sludge. This strain has strong N2O reduction capability, and the average N2O reduction rate was 5.10 ± 0.11 × 10-9 µmol·h-1·cell-1 under anaerobic condition in a defined medium. This reduction was accompanied by the stoichiometric consumption of acetate over time when N2O served as the sole electron acceptor and the reduction can yield energy to support microbial growth, suggesting that microbial N2O reduction is related to the energy generation process. Genomic analysis showed that the gene cluster encoding N2O reductase of P. denitrificans R-1 was composed of nosR, nosZ, nosD, nosF, nosY, nosL, and nosZ, which was identified as that in other strains in clade I. Respiratory inhibitors test indicated that the pathway of electron transport for N2O reduction was different from that of the traditional electron transport chain for aerobic respiration. Cu2+, silver nanoparticles, O2, and acidic conditions can strongly inhibit the reduction, whereas NO3- or NH4+ can promote it. These findings suggest that modular N2O reduction of P. denitrificans R-1 is linked to the electron transport and energy conservation, and dissimilatory N2O reduction is a form of microbial anaerobic respiration.
OBJECTIVE: Nitrous oxide (N2O) is a potent greenhouse gas and contributor to ozone layer destruction, and atmospheric N2O has increased steadily over the past century due to human activities. The release of N2O from fixed N is almost entirely controlled by microbial N2O reductase activities. Here, we investigated the ability to obtain energy for the growth of Paracoccus denitrificans R-1 by coupling the oxidation of various electron donors to N2O reduction. The modular N2O reduction process of denitrifying microorganism not only can consume N2O produced by itself but also can consume the external N2O generated from biological or abiotic pathways under suitable condition, which should be critical for controlling the release of N2O from ecosystems into the atmosphere.