Seminar of the Department of Microbiology

MSc Student Session 3

Sara Hnaien – MSc candidate – UIBK – Mykologie

Dominick Mündges – MSc candidate – UIBK – Environmental OMICS

Lisa Hagmann – MSc candidate – UIBK – Mykologie

24.04.2024, 11:00

Join online
or in presence: Seminarraum Biologie - (Technikerstr. 25, Viktor-Franz-Hess Haus, Parterre)

Abstracts

Hnaien: Effects of cold drought and land use on plasmodiophorids/grass interactions

As climate change continues to impact ecosystems globally, understanding the interactions between microbes and host plants is increasingly important. This study focuses on the interaction between soil-borne plasmodiophorid parasites (in particular Polymyxa and Tetramyxa spp.) and the alpine grass Poa alpina, which is prevalent in alpine and subalpine regions. Given the increase in cold drought events due to climate change, this research investigates how varying drought conditions influence plasmodiophorid interactions with grasses. We aim to analyze the dynamics of this parasite-host interaction by simulating cold winter drought conditions in a controlled greenhouse environment. Three soil types will be utilized, and Poa alpina will be subjected to different irrigation treatments to assess the impact of water availability on infection rates and plant recovery. The study will evaluate key factors such as plant growth, resilience, and the prevalence of plasmodiophorid infections under these stress conditions. Additionally, the research will explore how recovery from drought impacts the fitness of Poa alpina post-drought. By employing phenotypical assessments, molecular analyses, and microscopy, this study seeks to provide insights into the ecological implications of climate-related stressors on plant-microbes dynamics. The findings will enhance our understanding of how environmental changes may shape the interactions between plasmodiophorids and Poa alpina.

Mündges: Plastic-eating superworms - Investigating plastic degrading abilities of insect larvae gut microbiomes

This project investigates the plastic-degrading potential of the gut microbiome of Zophobas morio larvae (“superworms”), focusing on polystyrene (PS) and polyethylene (PE). Following controlled feeding trials with plastic-based diets, DNA and RNA were extracted from larval gut samples to identify microbial taxa and enzymes potentially involved in polymer degradation. To validate findings, enrichment cultures were established using minimal media with ground PS or PE as the sole carbon source. Proteins from these cultures were extracted, sequenced, and analyzed. Bioinformatic analyses of metangenomic DNA and metatranscriptomic RNA sequencing data from feeding trials were compared to elucidate enzymatic pathways and microbial players in plastic degradation. Hidden Markov Models (HMM) were used to compare identified genes to known plastic-degrading proteins. Plastic degradation in fecal samples was assessed via Fourier-transform infrared spectroscopy (FTIR), which detects changes in molecular bonds. Feeding trials revealed higher survival rates in plastic-fed larvae compared to starvation controls, suggesting metabolic utilization of polymer-bound carbon. Metagenomic analyses revealed shifts in microbial communities between treatment groups. HMM analysis showed a higher number of hits to known plastic-degrading proteins in DNA from plastic-fed groups. Metagenome-assembled genomes (MAGs) revealed microbial taxa with varying numbers of HMM hits, identifying promising candidates for plastic degradation activity. RNA-seq expression profiles of known plastic degrading genes varied across treatment groups, suggesting transcriptional responses to plastic exposure. FTIR analysis did not reveal significant differences between untreated and fecal plastic samples, potentially due to contamination by gut content of fecal samples. For future experiments, FTIR measurements can be enhanced by washing fecal plastic samples. Increasing RNA sequencing depth can help to better understand plastic degradation in superworm guts on a transcriptomic level and thereby identify key proteins and microbes responsible. The results of this study provide a foundation for identifying enzymes and microbial pathways involved in plastic degradation and inform future efforts in biotechnological applications targeting treatment of plastic wastes.

Hagmann: The Effects of Cold Drought on the Infection of Plasmodiophora brassicae in Arabidopsis arenosa

Arabidopsis arenosa is a natural outcrosser of A. thaliana, distinguished by high genetic diversity and strong ecotypic differentiation. Notably, populations from subalpine and foothill habitats differ in life cycle, stress responses, and susceptibility to pathogens, making A. arenosa a valuable model system for studying plant adaptation and host-pathogen interactions. Plasmodiophora brassicae is an obligate biotrophic protist that infects the roots of Brassicaceae species, causing clubroot disease. The pathogen’s life cycle includes a primary infection of root hairs—leading to the formation of durable resting spores—and a secondary infection phase, which triggers hypertrophic growth and gall formation in cortical root tissues. Environmental conditions such as soil moisture, temperature, and pH are known to influence both the development and spread of the pathogen. However, the interaction between abiotic stress and host susceptibility remains poorly understood, particularly in non-cultivated hosts like A. arenosa. This study aims to investigate the infection response of three tetraploid A. arenosa genotypes (AA252 – foothill origin; AA253 and AA254 – subalpine origin) to P. brassicae under combined cold and drought stress in a controlled environment. Disease severity will be assessed through disease incidence (DI) and disease severity index (DSI), along with detailed morphological analysis using digital phenotyping. In addition, the expression of the stress-related genes ERD7 and JAZ7 will be quantified to evaluate genotype-specific stress responses during infection.