An Indian physicist zooms in on microbes

Dr Arnika Karuna is sitting in a room full of technical equipment.

As a teenager, Arnica Karuna was fascinated by outer space with its stars and planets, supernovae and black holes. Later, when she was studying physics, spectroscopy became her "thing" – a method of chemical analysis that measures the interaction of matter with electromagnetic waves: "It spoke to me because it offers so many possibilities and so many applications", says Arnica Karuna. Ever since, her special interest – which caused her three sisters at home to label her as a nerd – has taken the young Indian woman from Delhi halfway around the world.

She opted to do her PhD in the United Kingdom. At Cardiff University in Wales, she studied a microspectroscopic method of analysing cells and tissue. She then spent some years researching in Belgium and the Netherlands. Since April 2020 she has been one of 19 postdocs at the Balance of the Microverse Cluster of Excellence at Friedrich Schiller University in Jena in eastern Germany, where research is centred around microorganisms, i.e. bacteria, fungi and other microscopic organisms. Their importance can hardly be overestimated – in terms of human and animal health, soil fertility or indeed the ecological balance in water bodies. Microspectroscopic methods are a particularly good way of examining single cells and microorganisms. "We do not need to stain or label our samples, we exploit intrinsic molecular contrast through the spectral information we acquire", explains Karuna. This is a very precise method, for every individual molecule has a unique spectral signature.

Leading research group in Jena

The physicist had already heard of the University of Jena before she applied for the postdoc position there. Karuna knew that the microspectroscopy working group at the Abbe Center of Photonics was the world's leading research group in this field. She then wrote to its director who told her about the cluster, which was set up in 2018. "The idea of the Microverse Cluster spoke to me because of the imaging centre that provides and develops state-of-the-art biomedical imaging technologies", says Karuna. She explains that she had previously worked mainly on application problems, researching for instance the effect at cellular level of a cancer treatment that was being developed. "Here at the cluster I can advance my experimental and technological skills. My eventual goal is to develop a setup for high-resolution and high-throughput multimodal imaging of the microbes."

Countless different microorganisms

Her workplace at the Abbe Center of Photonics is situated in the south of Jena, at the Beutenberg Campus. The science centre's slogan is "Life Science meets Physics", and it is this interdisciplinary collaboration that Karuna appreciates in particular. "The cluster comprises medicine, biology, physics, ecology, chemistry and data science", says the researcher. "It is truly interdisciplinary at a scale I have not seen before." However, when she walks along the hilly path from her flat to the lab each morning she is not yet thinking about microorganisms and how best to make them visible; this is the time of day she prefers to devote to poetry. "When I see something that draws my attention, I make up a poem in my mind. It is usually nature, and Jena is full of natural beauty", she enthuses.

Most of her poems are fleeting because she does not write them down. Microbes, on the other hand, she records by means of spectroscopy. This is one step on the path to researching the countless different microorganisms that continuously interact with one another and with their surroundings in order to survive. Research into these microbial communities is still very much in its infancy. Together, the scientists at the Microverse Cluster are keen to identify the overarching principles according to which they interact – with a view to developing new medical treatments and better understanding ecological processes. This will require a great deal of patience. "One should always persevere", as Arnica Karuna would say. This is a motto that she herself has always valued and taken to heart.