Bacterial denitrification gene expression in the rhizosphere

整个研究计划将通过逆转录-真实的时间PCR定量反硝化基因的表达在不同的土壤条件下，包括根际假单胞菌和土著土壤微生物。全球变暖已被确定为对我们共同、共有的生物圈的一个优先国际威胁，造成了难以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（N2 O）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N2 O的浓度一直以每年0.2-0.3%的惊人速度增长。 本人和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、非均质土壤和根际中的表达。 曼氏假单胞菌是从我所研究的土壤中分离出来的一种优势微生物。因此，继续研究这个物种以完成更全面了解所需的数据集是明智和合乎逻辑的。 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物、散装土壤和根际土壤中的一系列纯化基因表达的影响（通过实时PCR逆转录、数字基因表达分析和蛋白质组学）。还将测量一氧化二氮的排放和氮基质的消耗。在植物根系的影响下，根际土壤中的基因表达速率可能与同一块土壤中的基因表达速率存在显著差异。 根际硝酸盐含量的增加和反硝化菌密度的提高可能会导致反硝化基因的诱导时间更长，从而导致更多的N2 O产物释放到大气中，但前提是通过添加肥料获得氮基质和/或土壤硝化作用。在厌氧条件下开始反硝化之前，在好氧条件下进行。

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.