Microbes are absolutely tiny. Is that why their importance has been underestimated up to now?
Thomas Bosch: Absolutely. Modern sequencing techniques such as metagenomics and metabolomics have shown that for a long time we overlooked many living beings. More than half of the cells in our bodies are microbial cells. Almost nobody expected that these microorganisms would have such a large influence on our development and health.
Interview Host + microbe = metaorganism
- Molecular Biology
- Medical Research
- Biomedicine
Microbes are tiny life forms that cannot be seen by the human eye. They include single-cell organisms such as bacteria and protozoa as well as multicell organisms such as fungi and algae. Some of these tiny organisms depend on a host in order to live and survive. At the same time, the host also benefits, for example with respect to digestion and immune defence. Leopoldina member Thomas Bosch’s research into the freshwater polyp Hydra has significantly enhanced our understanding of the connection between host and microbes and helped establish the new biological concept of a “metaorganism”. On 15 April, the zoologist and developmental biologist will speak at the Leopoldina about the discovery of the metaorganism and its potential as a research subject.
Questions and answers
Question
What are Metagenomics and Metabolomics?
Answer
Metagenomics and Metabolomics belong to the modern bioscience “omics” technologies that make it possible to analyse entire biological systems. Metagenomics shows which microorganisms are present in an environmental or bodily sample and which genetic material they possess. From this analysis it is possible to draw conclusions about which metabolic potential the microorganisms have. Metabolomics, meanwhile, shows the biochemical activity, meaning which metabolic products actually arise. The result is a comprehensive picture of the genetic make-up of microbes, ranging from their functions to the molecules produced, thus enabling insight into complex ecosystems such as the gut and its microbiome.
What role do microorganisms play in evolution?
Bosch: They play a central role. Microbes have existed for around 3.5 billion years, animals and plants for only around 560 million years. Without microbes there would be no complex life forms. Plants, animals, and humans depend on them. Life in extreme habitats, such as deserts or in high mountain regions, is only possible via interaction with microbes. Even everyday processes such as digesting grass by rumination only function thanks to specialised microbes.
You study the microbiome of the freshwater polyp Hydra. What makes this organism so special?
Bosch: Hydra is a very simple but, from an evolutionary perspective, old animal. That’s precisely what makes it so useful for research. It also has a simple body structure. In addition, its microbiome is relatively lacking in complexity and can be cultivated. As it is possible to genetically alter both the Hydra host and its microbes in a targeted manner, cause and effect can be studied directly. If the microbes are removed, the nervous system, for example, does not develop properly. This shows how fundamental microorganisms are for animal life – and this has been the case for millions of years.
Expert on the topic Professor Dr Thomas C. G. Bosch ▸
- Genetics/Molecular Biology and Cell Biology
- Election year 2025
Host and microoganisms must therefore be seen as a joint metaorganism? What exactly do you mean by this?
Bosch: No organism exists for itself alone. Plants, animals, and humans are always a living community consisting of host and microorganisms. Many processes relating to health and illness can only be understood when this connection is considered. The new insights require a holistic approach. The metaorganism is therefore a new basic biological concept.
What opportunities does this new concept offer science?
Bosch: We have to change the way we think about many biological systems, for example the immune system. For a long time, it was primarily seen as a defence against pathogens. We now know that microbes on our skin or in the oral cavity are an active part of this defence. Without these microbes we would be much more vulnerable to infections. New perspectives are also arising with respect to neural functions. Microbial molecules formed in the gut influence the nervous system and even behaviour via the gut-microbiome-brain axis. It is also likely that an altered microbiome plays a role in neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
Is the microbiome negatively affected by changes in its environment?
Bosch: Without a doubt. Diseases related to lifestyle, such as obesity, neurodermatitis, and allergies have increased greatly since the 1950s. Our modern nutrition and lifestyle habits are a burden on many microbes. They are lost, and that is not without consequences for our health.
How can research help support the microbiome?
Bosch: When we understand why we lose the “good” microbes in our urban environment, we can also begin to reflect on how we can bring them back into our environment and into plants, animals, and humans. This is currently a hugely exciting element of metaorganism research.
The interview was conducted by Benjamin Haerdle