Doctor Sebastian Horn

Sebastian HornDr Sebastian Horn joined the Hawkesbury Institute for the Environment in October 2015. His fellowship is linked to the Australian Research Council (ARC) grant of Dr Uffe Nielsen, "The legacy of rainfall patterns in dryland ecosystems".

Dr Horn received his Ph.D. from Freie Universität of Berlin in 2015 under the primary supervision of Prof Matthias Rillig. His Ph.D. focused on the community composition of arbuscular mycorrhizal fungi (AMF) in dry, nutrient-poor grasslands. Using next-generation sequencing and advanced statistics, he was able to elucidate important community assembly rules of the AMF.

After acquiring his diploma in Biology for investigating gene-expression systems in the green algae Chlamydomonas reinhardtii in 2009, Dr Horn felt that being a good scientist required to look at biological systems in a broader scientific context. Before joining the group of Prof Rillig, he therefore worked from 2009 to 2011 in the biophysics department of Freie Universität with Prof Dau, exploring the fine-structure of protein centers with X-ray absorption spectroscopy.

During his time in the lab of Prof Rillig in Berlin, Germany, from 2011 to 2015, he combined his passion for molecular soil biology with biostatistics and forged it into an expertise for next-generation metagenomics on below-ground organisms, mainly endophytic fungi. After the project for his Ph.D. ended, he focused on exploring the functionally enigmatic group of Sebacinales fungi. A scholarship as a visiting fellow at the HIE in 2014 showed him the excellent opportunities of studying soil microorganisms in Australia, so he took the opportunity to join the HIE as a research fellow one year later.

Dr Horn's current focus lies in the exploration of rainfall regime pattern changes. Rainfall patterns are significantly influenced by climate change, influencing biological activity of ecosystems. This could moderate how organisms interact, potentially causing trophic cascades and even ecosystem state changes. By linking observed responses with soil microbial functional attributes using newly developed molecular techniques, Dr Horn seeks to provide a mechanistic insight into ecosystem responses to climate variability and extreme climatic events. He is particularly interested in fungi and bacteria, but also includes mites, nematodes, protists and other microorganisms in his current studies.

Areas of Research

Dr Horn's research incorporates molecular, physiological and bioinformatics tools to understand community assembly rules and link them to environmental properties of an ecosystem. He uses spatial and phylogenetic modelling to understand mechanisms of community ecology.

Dr Horn applies next-generation sequencing in combination with multivariate statistics and soil characterization to conduct functional analyses and metagenomics. Statistical tools of his choice are linear models, variance partitioning, structural equation models, null models, neutral models, eigenvector mapping and phylogenetic distance models.

Selected publications

Camenzind T, Hammer EC, Lehmann J, Solomon D, Horn S, Rillig MC, Hempel S, (2018) 'Arbuscular mycorrhizal fungal and soil microbial communities in African Dark Earths', FEMS Microbiology Ecology, vol.94, no.4, Article no.fiy033

Horn S, Hempel S, Verbruggen E, Rillig MC, Caruso T, (2017) 'Linking the community structure of arbuscular mycorrhizal fungi and plants: a story of interdependence?', ISME Journal, vol.11, no.6, pp 1400-1411

Lopez-Garcia A, Horn S, Rillig MC, Hempel S, (2016) 'Spatial and niche-based ecological processes drive the distribution of endophytic Sebacinales in soil and root of grassland communities', FEMS Microbiology Ecology, vol.92, no.6, Article no. fiw079

Horn S, Hempel S, Ristow M, Rillig MC, Kowarik I, Caruso T, (2015) 'Plant community assembly at small scales: spatial vs. environmental factors in a European grassland', Acta Oecologica, vol.63, pp 56-62

Camenzind T, Hempel S, Homeier J, Horn S, Velescu A, Wilcke W, Rillig MC, (2014) 'Nitrogen and phosphorus additions impact arbuscular mycorrhizal abundance and molecular diversity in a tropical montane forest', Global Change Biology, vol.20, no.12, pp 3646-3659

Horn S, Caruso T, Verbruggen E, Rillig MC, Hempel S, (2014) 'Arbuscular mycorrhizal fungal communities are phylogenetically clustered at small scales', The ISME Journal, vol.8, no.11, pp 2231-2242

Reschke S, Sigfridsson KGV, Kaufmann P, Leidel N, Horn S, Gast K, Schulzke C, Haumann M, Leimkühler S, (2013) 'Identification of a bis-molybdopterin intermediate in molybdenum cofactor biosynthesis in Escherichia coli', The Journal of Biological Chemistry, vol. 288, vol.41, pp 29736-29745