School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, UK.
School of Medical Science, Griffith University, Gold Coast campus, Southport, Australia.
Environ Microbiol. 2017 Dec;19(12):4953-4964. doi: 10.1111/1462-2920.13974. Epub 2017 Dec 4.
Bacterial denitrification is a respiratory process that is a major source and sink of the potent greenhouse gas nitrous oxide. Many denitrifying bacteria can adjust to life in both oxic and anoxic environments through differential expression of their respiromes in response to environmental signals such as oxygen, nitrate and nitric oxide. We used steady-state oxic and anoxic chemostat cultures to demonstrate that the switch from aerobic to anaerobic metabolism is brought about by changes in the levels of expression of relatively few genes, but this is sufficient to adjust the configuration of the respirome to allow the organism to efficiently respire nitrate without the significant release of intermediates, such as nitrous oxide. The regulation of the denitrification respirome in strains deficient in the transcription factors FnrP, Nnr and NarR was explored and revealed that these have both inducer and repressor activities, possibly due to competitive binding at similar DNA binding sites. This may contribute to the fine tuning of expression of the denitrification respirome and so adds to the understanding of the regulation of nitrous oxide emission by denitrifying bacteria in response to different environmental signals.
细菌反硝化是一种呼吸过程，是强温室气体氧化亚氮的主要源和汇。许多反硝化细菌可以通过呼吸组在氧气、硝酸盐和一氧化氮等环境信号的作用下的差异表达来适应好氧和缺氧环境。我们使用稳态好氧和缺氧恒化器培养物证明，从需氧到厌氧代谢的转变是由相对少数基因表达水平的变化引起的，但这足以调整呼吸组的配置，使生物体能够有效地呼吸硝酸盐，而不会显著释放中间体，如氧化亚氮。研究了转录因子 FnrP、Nnr 和 NarR 缺失菌株中反硝化呼吸组的调节情况，结果表明这些因子具有诱导和抑制作用，可能是由于在类似的 DNA 结合位点上的竞争结合。这可能有助于反硝化呼吸组表达的精细调控，从而增加了对反硝化细菌响应不同环境信号时一氧化二氮排放的调控的理解。
