Lipidomics and functional genetics of the terrestrial microbial N-Cycle
Final Report Abstract
The project aimed at a parallel characterization of microbes participating in the cycling of nitrogen in the biogeosphere using lipid and molecular genetic indicators. For this purpose, a suite of 120 samples were collected in China by the research partner Zhu Guibing, who intended to execute the molecular genetics work on these samples. An aliquot of sample transferred to Kiel University was investigated for bulk organic matter properties and lipid composition. Determination of the organic matter properties revealed that in selectively sampled couplets of adjacent land and water ecotypes, the organic matter in grasslands to a large degree originated from aquatic sources, i.e. aquatic macrophyte plants and cyanobacteria. This was attributed to either episodic flooding of grasslands near to the river or to changes in land use over time. Alternations in environmental conditions were considered to be to strongly variable and fluctuating for an investigation of contributions of microbes to the N-cycle. The complementary analysis of molecular genetic data on this coherent sample set could not be realized due to lack of funding. The complexity of the nitrogen cycle was thus investigated further in joint research activities, for our collaboration partner in Beijing funded by other projects and here focussed on anaerobic ammonium oxidation (anammox). Here, it was found that highest intensities of anammox occurred at land-freshwater interfaces from riparian lake zones, whereby rates of anammox peaked in sediments sampled from the landwater interface, as did the abundance of annamox bacteria. It was estimated that interfacial anammox hotspots account for the loss of 103 gNm2 yr^-1 from this lake region with 20% nitrogen lost from the land–water ecotone. In another study the reaction of dormant anammox microbes to reactivation by addition of water was studied and found to be feasible even after 10.000 years of inactivity, whereby water induced reduction of nitrate to nitrite, a prerequisite reaction to stimulate utilization by anammox bacteria via dissimilatory nitrite reduction to ammonium. Under global climate change, increasing precipitation and soil moisture may revive dormant anammox bacteria in arid soils and thereby impact global nitrogen and carbon cycles. A last study addressed the role of complete ammonia oxidation (comammox) in nitrification the rate-limiting process in the global nitrogen cycle. Comammox bacterial abundance and rate varied seasonally and dominated in non-rhizosphere versus rhizosphere soil, with fringe soils in riparian zones comprising a hotspot and contributing the most to the ammonium oxidation processes.
Publications
- (2015) Chemotaxonomy and diagenesis of aliphatic hydrocarbons in rice plants and soils from land reclamation areas in the Zhejiang Province, China. Organic Geochemistry 8, 215-226
Mueller-Niggemann, C., Schwark L.
(See online at https://doi.org/10.1016/j.orggeochem.2015.03.016) - (2016) Distribution of tetraether lipids in agricultural soils – differentiation between paddy and upland management. Biogeosciences13, 1647- 1666
Mueller-Niggemann, C., Utami, S.R., Marxen, A., Mangelsdorf, K., Bauersachs, T., Schwark, L.
(See online at https://doi.org/10.5194/bg-13-1647-2016) - (2016) Source and depth translocation of combustion residues in Chinese agroecosystems determined from parallel polycyclic aromatic hydrocarbon (PAH) and black carbon (BC) analysis. Organic Geochemistry 98, 27-37
Mueller-Niggemann, C., Lehndorff, E., Amelung, W., Schwark, L.
(See online at https://doi.org/10.1016/j.orggeochem.2016.04.013) - (2019). Resuscitation of anammox bacteria after >10,000 years of dormancy. ISME Journal 13, 1098-1109
Zhu, G., Wang, S., Wang, C., Zhou, L., Zhao, S., Li, Y., Li, F., Jetten, M.S.M, Lu, Y., Schwark, L.
(See online at https://doi.org/10.1038/s41396-018-0316-5) - (2020) Anaerobic ammonium oxidation is a major N-sink in aquifer systems around the world. ISME Journal 14, 151-163
Wang, S., Zhu, G., Zhuang, L., Li, Y., Liu, L., Lavik, G., Berg, M., Liu, S., Long, X., Guo, J., Jetten, M.S.M., Kuypers, M.M.M., Li, F., Ni, J., Schwark, L., Yin, C.
(See online at https://doi.org/10.1038/s41396-019-0513-x) - (2021) Abundance and Functional Importance of Complete Ammonia Oxidizers and Other Nitrifiers in a Riparian Ecosystem. Environmental Science & Technology 55, 4573- 4584
Wang, S., Wang, X., Jiang, Y., Han, C., Jetten, M.S.M., Schwark, L., Zhu, G.
(See online at https://doi.org/10.1021/acs.est.0c00915)
