Distribution of contaminant degraders and redox guilds and expression of degradation genes in stationary and non-stationary contaminant plumes

TP4B的目的是了解氧化还原振荡和水力转移如何影响污染物降解菌和厌氧微生物群落的空间分布和活性。该研究股的一个核心假设是，在非静止条件下，污染物羽流的混合程度增加，预计会增强净生物降解活动。另一方面，我们假设，完善的生物降解能力（即高度专业化的降解菌群）是在高反应区进行有效生物降解的必要前提。生物降解可以假设减少，甚至崩溃下的氧化还原波动引起的水力转变，如果固着降解人口突然面临相反的生物地球化学条件下，并重新建立在不同的沉积层。在第二阶段的资助的FOR252，我们已经提供了初步的证据，重要的污染物降解微生物种群的定性和定量分布模式受到意想不到的时间动态在外地。观察到的“崩溃”的既定降解人口连接到显着的时间振荡的污染物羽。这些新的发现将有助于更详细地了解影响和控制该领域污染物降解微生物种群的因素。在这个研究单位的最后一年半（我们在此申请12个月的资金），我们的目标是进一步阐述和更深刻地建立这些概念，通过持续的时间分辨采样在外地，解决也短期动态。此外，一个既定的发光bioreporter菌株将采用在2D含水层围隔生态系统，以遵循和建模的发展，一个特定的降解人口和活动的污染物羽流的建立，并在非静止条件下。因此，模拟微生物降解活动的分布及其对罐混合增加的适应性，实际上将可通过时间和空间分辨的非侵入性数据进行测试。

The aim of TP4B in this Research Unit is to understand how redox oscillations and hydraulic shifts influence the spatial distribution and activity of contaminant degraders and anaerobic microbial communities in the field. It is a central hypothesis of this Research Unit that increased mixing in contaminant plumes under non-stationary conditions can be expected to enhance net biodegradation activities. On the other hand, we hypothesize that well established biological degradation capacities (i.e. highly specialised degrader populations) are an essential prerequisite for effective biodegradation in highly reactive zones. Biodegradation can be hypothesized to decrease or even collapse transiently under redox fluctuations caused by hydraulic shifts, if sessile degrader populations suddenly face opposing biogeochemical conditions, and have to re-establish in different sediment strata. In the 2nd phase of funding of the FOR252, we have provided primary evidence that the qualitative and quantitative distribution patterns of important contaminant-degrading microbial populations are subject to unexpected temporal dynamics in the field. An observed “collapse” of the established degrader population was connected to pronounced temporal oscillations of the contaminant plume. These are novel findings that will help to establish a more detailed understanding of the factors that affect and control contaminant degrading microbial populations in the field. In the last 1.5 years of this Research Unit (12 months of funding we hereby apply for), we aim to further elaborate and more profoundly establish these concepts by continued time-resolved samplings in the field, addressing also short-time dynamics. Furthermore, an established luminescent bioreporter strain will be employed in 2D aquifer mesocosms to follow and model the development of a specific degrader population and activities over the establishment of a contaminant plume, and also under non-stationary conditions. Thus, simulations of the distribution of microbial degradation activities and their adaptation to increased mixing for the tanks will actually become testable with temporally and spatially resolved non-invasive data.