Bacterial denitrification gene expression in the rhizosphere

整个研究计划将通过逆转录-实时聚合酶链式反应(RT-Real-Time PCR)来量化反硝化基因在不同土壤条件下(包括根际)在假单胞菌和本土土壤微生物中的表达。全球变暖已被确定为对我们共同的、共有的生物圈的一个优先国际威胁，造成了无法轻易估计和预测的巨大社会、环境、农业、公共卫生和经济后果。一氧化二氮(N2O)是导致全球变暖的几种温室气体之一。自前工业化时期以来，大气中N2O的浓度一直在以每年0.2-0.3%的惊人速度增长。 我和我的合作者设计了一系列实验，进行了为期5年的研究，以了解反硝化基因在纯培养、散装土壤和根际中的表达。曼德利假单胞菌是从我一直在研究的土壤中分离出来的一种优势反硝化细菌。因此，继续研究这一物种以完成更全面了解所需的数据集是谨慎和合乎逻辑的。 人们正在研究植物、细菌和土壤环境之间的复杂功能关系，以确定环境的影响，包括根际效应对纯培养土壤、散装土壤和根际土壤中的一系列反硝化基因表达的影响(通过实时荧光聚合酶链式反应反转录、数字基因表达分析和蛋白质组学)。还将测量一氧化二氮排放和N基板的消耗。与相同的土壤相比，受植物根系影响的根际可能表现出显著不同的基因表达速率。 根际硝酸盐含量的增加和反硝化菌密度的增加可以导致反硝化基因的诱导时间延长，从而导致更多的N2O产物释放到大气中，但前提是N-基质是有效的，并且/或者土壤在好氧条件下进行硝化，然后在厌氧条件下开始反硝化。

The overall research program will quantify denitrification gene expression via reverse transcription- Real time PCR in Pseudomonas mandelli and indigenous soil microorganisms under diverse soil conditions including the rhizosphere. Global warming has been identified as a priority international threat to our common, shared, biosphere, resulting in immense social, environmental, agricultural, public health and economic consequences that cannot be easily estimated and forecasted. Nitrous oxide (N2O) is one of several greenhouse gases that contribute to global warming. Atmospheric concentrations of N2O have been increasing at an alarming rate of 0.2-0.3% per year since the preindustrial period. A series of experiments have been designed by myself and my collaborators, for a 5-year period of research to understand denitrification gene expression in pure culture, bulk soil and the rhizosphere. P.mandelii is a predominant denitrifying bacterium isolated from the soils I have been researching. It is therefore prudent and logical to continue researching this species to complete the data sets required for a more complete understanding. The complex functional relationships between plants, bacteria and the soil environment are being researched to determine the effect of the environment including the rhizosphere effect on the suite of denitrifying gene expressions (via Real-time PCR reverse transcription, digital gene expression analysis and proteomics) in pure cultures, bulk and rhizosphere soils. Nitrous oxide emissions and depletion of the N-substrates will also be measured. The rhizosphere under the influence of plant roots may exhibit significantly different rates of gene expression compared to the same bulk soil. Increasing amounts of nitrate and a higher density of denitrifiers in the rhizosphere could result in longer induction times of denitrification genes and subsequently, more N2O product released into the atmosphere, but only if N-substrate is available by addition of fertilizer and/or soil nitrification is occurring under aerobic conditions before denitrification commences under anaerobic conditions.