Anoxic growth of Ensifer meliloti 1021 by N2O-reduction, a potential mitigation strategy.
Anoxic growth of Ensifer meliloti 1021 by N2O-reduction, a potential mitigation strategy.
复制标题
DOI：
10.3389/fmicb.2015.00537
复制
发表时间：
2015
影响因子：
5.2
通讯作者：
Delgado MJ
中科院分区：
文献类型：
--
作者：
Bueno E;Mania D;Frostegard Ǻ;Bedmar EJ;Bakken LR;Delgado MJ
农业土壤中的反硝化作用是N2O的主要来源。豆类作物通过提供富含N的残留物，从而刺激自由生活的反硝化细菌和根瘤内的共生菌(根瘤菌)的反硝化作用，从而增加N2O的排放。然而，关于豆类作物内共生细菌产生和消耗N2O的数据有限。据报道，紫花苜蓿内共生菌Meliloti菌株1021虽然拥有并表达全套反硝化酶，但在缺氧条件下不能通过硝酸盐呼吸生长。在本研究中，我们通过使用机器人培养系统证明了该细菌能够通过N2O厌氧呼吸转变为氮气而生长。N2O还原酶(N2OR)的活性不依赖于氮氧阴离子或NO的存在，因此它的表达可以被单独的氧气耗竭所诱导。当在pH 6下培养时，美洲斑潜蝇不能还原N2O，这证实了之前在提取的土壤细菌和脱氮副球藻纯培养中发现的观察结果，在低pH下很难表达功能性的N2O还原酶。此外，在培养基中存在高度还原的C-底物，如丁酸盐，对N2OR活性产生负面影响。豆科植物接种高表达N2O还原酶的根瘤菌可以降低土壤中N2O的排放。这项研究表明，像E.Meliloti 1021这样的菌株可以作为更好的N2O汇，这些菌株不产生N2O，但能够减少其他生物排放的N2O。
Denitrification in agricultural soils is a major source of N2O. Legume crops enhance N2O emission by providing N-rich residues, thereby stimulating denitrification, both by free-living denitrifying bacteria and by the symbiont (rhizobium) within the nodules. However, there are limited data concerning N2O production and consumption by endosymbiotic bacteria associated with legume crops. It has been reported that the alfalfa endosymbiont Ensifer meliloti strain 1021, despite possessing and expressing the complete set of denitrification enzymes, is unable to grow via nitrate respiration under anoxic conditions. In the present study, we have demonstrated by using a robotized incubation system that this bacterium is able to grow through anaerobic respiration of N2O to N2. N2O reductase (N2OR) activity was not dependent on the presence of nitrogen oxyanions or NO, thus the expression could be induced by oxygen depletion alone. When incubated at pH 6, E. meliloti was unable to reduce N2O, corroborating previous observations found in both, extracted soil bacteria and Paracoccus denitrificans pure cultures, where expression of functional N2O reductase is difficult at low pH. Furthermore, the presence in the medium of highly reduced C-substrates, such as butyrate, negatively affected N2OR activity. The emission of N2O from soils can be lowered if legumes plants are inoculated with rhizobial strains overexpressing N2O reductase. This study demonstrates that strains like E. meliloti 1021, which do not produce N2O but are able to reduce the N2O emitted by other organisms, could act as even better N2O sinks.
登录
查看更多内容
DOI：
10.1098/rstb.2011.0321
发表时间：
2012-05-05
期刊：
Philosophical transactions of the Royal Society of London. Series B, Biological sciences
影响因子：
--
作者：
Bakken LR;Bergaust L;Liu B;Frostegård A
通讯作者：
Frostegård A
DOI：
10.1099/mic.0.054148-0
发表时间：
2012-03
期刊：
Microbiology (Reading, England)
影响因子：
--
作者：
Bergaust L;van Spanning RJM;Frostegård Å;Bakken LR
通讯作者：
Bakken LR
影响因子：
3.8
作者：
Baggs, EM;Rees, RM;Vinten, AJA
通讯作者：
Vinten, AJA
影响因子：
2.2
作者：
Inaba S;Ikenishi F;Itakura M;Kikuchi M;Eda S;Chiba N;Katsuyama C;Suwa Y;Mitsui H;Minamisawa K
通讯作者：
Minamisawa K
影响因子：
2.8
作者：
Arai, H;Mizutani, M;Igarashi, Y
通讯作者：
Igarashi, Y