Graduate Students Mini-Symposium III 2025

13:15 h Rebecca Schira - AG Bischofs-Pfeifer

How do dormant cells respond to environmental fluctuations? – Quantitative insights into bioelectric changes of B. subtilis spores

Maintenance of electrochemical gradients by living cells is key to energetic, homeostatic and signaling processes. In this talk, I will address if dormant Bacillus subtilis spores are able to do so as well. To this end, I will introduce our novel non-invasive approach to monitor individual internal spore pH dynamics. I will show how ambient pH and salinity changes trigger slow spore pH transitions, indicative of proton electrochemical gradient dissipation by passive proton fluxes. Our model-based estimates propose that the dynamic bioelectric spore state (pH, electric voltage) at the time of revival could be strongly controlled by the environment.

13:45 h Maria del Carmen Sánchez Olmos - MaxGENESYS Biofoundry – AG Schindler

Metagenomics to decode synthetic populations, towards lignin valorization in yeast

Lignin valorization represents a greener and sustainable solution to replace oil-derived products. However due to its recalcitrant nature it has remain underexploited. In nature, exist a great variety of microorganisms capable of depolymerize and mineralize lignin. Some members of bacteria and white-rot fungi secrete a complete repertoire of enzymes to degrade and further assimilate lignin. Specifically, secreted enzymes such as laccases play a crucial role for lignin depolymerization. Laccases have a big relevance in the biotechnological industry because of its high promiscuity. Therefore, multiple efforts have been made to improve laccase properties, such as its thermo and alkali tolerance. Thanks to its versatility and high recombination efficiency rate, Saccharomyces cerevisiae is the organism of choice to evolve enzymes. S.cerevisiae, provides the metabolic chassis not only to engineer proteins but complete metabolic pathways. In addition, the Synthetic Yeast 2.0 project (Sc2.0) provides with a full set of synthetic chromosomes to improve metabolic and cellular features by doing large scale genomic evolution. In this work we show for the first time the coupling of protein engineering of a small laccase from Amycolatopsis sp. (strain ATCC 39116 / 75iv2) displayed on the cell wall of S.cerevisiae. Furthermore, we demonstrate the big potential found in genome and metagenome repositories to find promising laccases with improved properties that contribute ultimately to lignin depolymerization.