Nerves control the body’s bacterial community




A central aspect of life sciences is to explore the symbiotic cohabitation of animals, plants and humans with their specific bacterial communities. Scientists refer to the full set of microorganisms living on and inside a host organism as the microbiome. Over the past years, evidence has accumulated that the composition and balance of this microbiome contributes to the organism’s health. For instance, alterations in the composition of the bacterial community are implicated in the origin of various so-called environmental diseases. However, it is still largely unknown just how the cooperation between organism and bacteria works at the molecular level and how the microbiome and body exactly act as a functional unit.

An important breakthrough in deciphering these highly complex relationships has now been achieved by a research team from Kiel University’s Zoological Institute. Using the freshwater polyp Hydra as a model organism, the Kiel-based researchers and their international colleagues investigated how the simple nervous system of these animals interacts with the microbiome. They were able to demonstrate, for the first time, that small molecules secreted by nerve cells help to regulate the composition and colonization of specific types of beneficial bacteria along the Hydra’s body column. “Up to now, neuronal factors that influence the body’s bacterial colonization were largely unknown. We have been able to prove that the nervous system plays an important regulatory role here,” emphasizes Professor Thomas Bosch, evolutionary developmental biologist and spokesperson of the Collaborative Research Centre 1182 “Origin and Function of Metaorganisms,” funded by the German Science Foundation (DFG). The scientists published their new findings in Nature Communications (September 2017).

The research team, led by Bosch, used the freshwater polyp Hydra as the model organism to elucidate the fundamental principles of nervous system structure and function. Hydra represent an evolutionary ancient branch of the animal kingdom; they have a simple body plan with a nerve net of only about 3000 neurons. Applying modern experimental technology to these organisms that, despite their simplicity, still share a large molecular similarity with the nervous systems of vertebrates, enabled identification of ancient and therefore fundamental principles of nervous system structure and function. Using this model organism, the researchers from Kiel University addressed the question of how messenger substances produced by the nervous system, known as neuropeptides, control the cooperation and communication between host and microbes. They collected cellular, molecular and genetic evidence to show that neuropeptides have antibacterial activity which affects both the composition and the spatial distribution of the colonizing microbes.

To reveal the connections between neuropeptides and bacterial communities, the Kiel-based researchers first concentrated on the development of the freshwater polyp’s nervous system, from the egg stage to an adult animal. Cnidarians develop a complete nervous system within about three weeks. During this developmental time, the bacterial communities covering the animal’s surface change radically, until a stable composition of the microbiome finally forms. Under the influence of the antimicrobial effect of the neuropeptides, the concentration of so-called Gram-positive bacteria, a subgroup of bacteria, decreases sharply over a period of roughly four weeks. At the end of the maturing process, a typical composition of the microbiome prevails, particularly dominated by Gram-negative Curvibacter bacteria. Since the neuropeptides are particularly produced in certain areas of the body only, they also control the spatial localization of the bacteria along the body column. Therefore, in the head region, for example, there is a strong concentration of antimicrobial peptides, resulting in six times fewer Curvibacter bacteria than on the tentacles.

Based on these observations, the scientists concluded that throughout the course of evolution the nervous system also participated in a controlling role for the microbiome, in addition to its sensory and motor tasks. “The findings are also important in an evolutionary context. Since the ancestors of these animals have invented the nervous system, it seems that the interaction between the nervous system and the microbiome is an ancient feature of multicellular animals. Since the simple design of Hydra has great basic and translational relevance and promises to reveal new and unexpected basic features of nervous systems, further research into the interaction between body and bacteria will therefore concentrate more on the neuronal aspects,” said Bosch, to summarize the significance of the work.

Adapted from: Kiel University. (2017, September 26). Nerves control the body’s bacterial community: Research team proves, for the first time, that there is close cooperation between the nervous system and the microbial population of the body. ScienceDaily. Retrieved December 20, 2017 from

Nutrition Tip of the Day

Keep a food diary! Most people don’t realize how much they really consume in a day. If you write it down, the amount you eat may surprise you.

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Fermented Foods: Top 5 Reasons to Eat Them

We are vigilant about germs. We sanitize our hands, sterilize our dishes, pasteurize food, and refrigerate and toss moldy or expired foods. But as it turns out, not all bacteria really is that bad for us. Our gut contains billions of helpful and harmful bacteria that we are exposed to even in utero. Antibiotics, essential for treating infections, affect the gut flora by destroying harmful and helpful bacteria. Genetics and environmental exposure can also alter our gut flora. The more beneficial bacteria we have, the healthier our bodies are which is why sales of probiotics are skyrocketing.

Why fermented foods?

Before refrigeration, fermenting food was a way people kept food from spoiling. Fermented foods are a natural way to improve and preserve a healthy gut flora. Fermented foods also have the ability to keep us healthy.

5 Reasons to Eat Fermented Foods

1. Improves digestive issues 
Bloating, constipation, and diarrhea are linked to a lack of healthy gut bacteria.

2. Maintains a healthy gut flora 
Lactose intolerance, gluten sensitivity, irritable bowel syndrome, recurring yeast infections, and allergies are all linked to an imbalance of gut bacteria.

3. Aids in weight loss 
Microbe-free mice injected with bacteria from obese people gained weight while mice injected with bacteria from thin people did not. When bacteria from thin people was injected into the obese mice, they lost weight.

4. Prevents chronic diseases
Autoimmune disorders, type 2 diabetes, and even cancer are linked to gut microbes.

5. Boosts your immune system
Healthy gut bacteria helps us absorb nutrients from food and filters out harmful substances which keeps our immune system healthy. It also helps with the production of some vitamins (B and K) which play a role in our immune function.

Ways to incorporate fermented foods into your diet

  • Eat sourdough bread instead of bread made with commercial yeast.
  • Drink fermented beverages such as coffee, tea, kombucha, kefir and red wine.
  • Eat yogurt regularly.
  • Incorporate pickles, sauerkraut, and olives into your diet.
  • Enjoy salsa, ketchup, sour cream, miso, and other naturally fermented condiments on a daily basis.
  • Eat tempeh, a protein-rich food made from fermented soybeans that can be added to stir-fry’s, soups and chili.

PCOS Nutrition Center