From bacterial food sources to cell gene activity: Four new, wild projects

Researcher: Kathrin Rousk, Associate Professor 
Grant amount: DKK 2.4 million 

Abstract: 
Endosymbiosis, the process where one organism engulfs another, has played a key role in the evolution of life on Earth. One of the most significant examples is the origin of plants: a free-living cyanobacterium was engulfed by a host cell, eventually evolving into the chloroplast, the photosynthesizing organelle in plant cells. Last year, a groundbreaking discovery identified another potential endosymbiosis event: a free-living, nitrogen (N)-fixing cyanobacterium was engulfed by a marine alga, forming the marine nitroplast. This new organelle supplies the host with newly fixed N, a key nutrient for all life. I propose here that we are at the dawn of a terrestrial nitroplost in moss-cyanobacteria symbioses, which can serve as a unique model system to unravel the evolution of a N-fixing organelle. Just as mitochondria and chloroplasts originated from ancient endosymbiotic events, the discovery of a terrestrial nitroplast would complete the “symbiotic trinity”, marking the third organelle acquired by plants. 

Researcher: Albin Sandelin, Professor 
Grant amount: DKK 2.5 million 

Abstract: 

Local pH and oxygen (O₂) levels are crucial for physiological homeostasis in organs. While the effects of O₂ and, to some extent, pH have been well studied in isolated cell models, their spatial and temporal dynamics and their impact on gene expression in individual cells within organs remain largely unknown. Methods within spatial transcriptomics can measure gene expression in cells in tissues, but there is a lack of methods for simultaneously mapping the effect of pH and O₂ microenvironments on gene expression in individual cells. This project will develop methods for measuring pH and O₂ levels in tissues and integrate these measurements with spatially resolved single-cell gene expression. By applying these methods to liver tissue, we will create models of how local O₂ and pH environments shape cellular gene expression and function. This represents an important step towards a quantitative molecular physiology of organ microenvironments. 

Researcher: Nan Yang, Postdoc 
Grant amount: DKK 2.3 million 

Abstract:  

The microbial world is shaped by various interactions ranging from cooperation (peace) to competition (war). Uncovering the ecological principles that drive these interactions has been a long-standing challenge in microbiology. Conventional wisdom holds that these interactions are genetically determined. But are there ‘ecological switch(es)’ that can shift microbial social behaviour between war and peace? WoP will explore ecological factors that regulate microbial activity and that may ultimately enable targeted control of interactions between species. The study aims to transform the current understanding of microbial interactions from being genetically determined to dynamically plastic. This concept is expected to reveal new biological mechanisms for microbial communication and potentially create tools to control microbial interactions in agriculture, industry and ecological applications. 

Researcher: Yong Zhan, Associate Professor 
Grant amount: DKK 2.5 million 

Abstract: 

In harsh environments such as oceans and deserts, bacteria often struggle to find food, even though they are surrounded by bacteriophages (phages)—viruses that normally infect and kill them. Phages are 10 times more numerous than bacteria and constitute an enormous amount of protein, fat, and genetic material. But because phages are picky eaters, most do not pose an immediate threat. We believe that bacteria may use non-infectious phages as a food source when nutrients are scarce. To test this, we will starve bacteria such as E. coli and feed them phages as their only food source. Using advanced tools, we will track how bacteria break down phages into nutrients such as sugars and amino acids, and identify the genes involved. If we are correct, it shows that phages are not only predators—they are also a vital food source for bacteria in hard times. This discovery could change our understanding of predator-prey relationships and microbial survival in extreme environments.