Citizen science success with sweet donations from Swedish beekeepers

Honeybees are our most important pollinators, and if they disappear, the consequences for our biodiversity would be devastating. In the EU, research on honeybee conservation is a high priority. Researchers at the Division of Industrial Biotechnology at Chalmers focus on exploring which yeast species are naturally present in honey.

Many questions surround honey yeast: Do yeast in honey contribute to bee health – and if so, how? Can compounds produced by yeast attract pollinating bees, and do these compounds have other functions? Are there known and unknown yeasts in Swedish honey that could be used in the food industry in the future?

To answer these questions, researchers need to identify and obtain basic knowledge of the yeast species found in honey.

“Honey is a hostile environment for most microbes to survive in, and it is interesting to see how the yeasts that survive the very high sugar content do so. Also, the so-called volatile organic compounds that the yeasts produce that contribute to the taste and texture of the honey – and perhaps to attract and repel pollinators and inhibit the growth of moulds and bacteria – are exciting,” says Cecilia Geijer, who together with Karl Persson, runs the project.

The samples resulted in a unique collection of yeast

The project, which aims to identify and characterize yeast in Swedish honey, started in the early summer of 2023 when the researchers posted an ad on Facebook targeting Swedish beekeepers. Within 30 hours, 120 beekeepers from all over the country had expressed interest in sharing their honey with the research project.

“We didn't know what kind of response we would get, so we prepared to send out a maximum of 20 kits for collecting honey. We had to revise this number quickly,” says Cecilia Geijer.

Together, the beekeepers have contributed to a unique collection of yeast strains isolated from honey, which can now be further investigated.

“It's great that this study has been received with open arms and that the beekeepers have been so committed. I've even received a personal delivery from one of our Chalmers’ alumni. We are very grateful — the project has grown and become so big thanks to the beekeepers,” says Karl Persson.

"Interesting if yeast provides protection for the bees"

One of the beekeepers who was involved before the project officially started is Agneta Persson, who lives in the Malingsbo-Kloten Nature Reserve in Dalarna. Her interest in beekeeping is shared with her husband, who in 2006 unearthed a treasure: Åke Hansson's book about bees and beekeeping, also known as the "Bible of beekeeping".

After attending a beekeeping course, he started his beekeeping career. Agneta Persson recalled her grandfather's beekeeping, which terrified her as a child, and initially wanted nothing to do with her husband's new interest.

"But slowly, my interest grew too. You wear protective gear when handling bees, so you simply don't get stung. My fear was completely unnecessary, and bees are very fascinating. It was hard to stay away," she says.

Over the years, Agneta Persson has developed the greatest interest in bees in the family. When her son Karl told her about the new research project he was working on, testing whether yeast could be cultivated from honey, she did not hesitate to contribute with research material.

"I am also a scientist, but I study microalgae and have a microscope at home. Pollen is the same size as my microalgae, so it made sense to look for pollen in the honey. By identifying the pollen, I can also see where the bees have been in our surroundings. But there is, of course, more to find out about the contents of honey," she says.

Agneta Persson is very curious about what the knowledge about bees and honey from the results of the Chalmers researchers' study could lead to in the future.

"Traditionally, honey has been attributed with health benefits, in addition to tasting very good. It would be interesting to know if yeast provides any protection for the bees and if the substances the yeast produce contribute flavor compounds or can produce substances that people can benefit from in some way," says Agneta Persson.

"We want to fill a knowledge gap"

In nature, hundreds of thousands of yeast species interact with plants, animals, and humans and thereby affect life on earth. Microorganisms in honey have likely ended up there after interacting with bees in one way or another, for example, via nectar.

Several studies show that microorganisms such as bacteria and moulds have a major impact on the honeybees’ behaviour, survival, and reproduction. It is far less known how different yeast species, which are rarely pathogenic, affect bees.

“Microorganisms are often associated with disease but can also have important protective roles. For example, there are studies on the health-promoting effects of lactobacilli on bees, but few have examined yeast in that way. We want to help fill this knowledge gap,” says Karl Persson. 

"Big difference in reading about beekeeping and experiencing it"

Emil Nyholm is one of the other beekeepers who has contributed to the project. For several years, he was eager to get a couple of beehives. He was fascinated by the insects' social structure and cooperation and wanted to experience it up close. But living in an apartment in Gothenburg and lacking a permit from the landlord when he wanted to place hives near his home made it difficult to practically pursue his interest.

"When my mom retired in 2018, we thought it could be a fun activity to do together, and we started beekeeping at the family cottage north of Skövde. I can admit that I was the eager project manager since I had read so much about the subject. However, reading about beekeeping and experiencing it are completely different things – interacting with the bees adds another dimension to the interest," he says.

Emil Nyholm also has brewing as an interest and therefore has some insight into fermentation processes and the yeast used in beer.

"I know that there is yeast in honey because honey with too much water can start fermenting, but my knowledge of honey yeast doesn't go much deeper than that. I think it's very exciting to contribute to the knowledge-building that the research project entails - it's exciting to get more detailed information about what happens in the beehive," he says, continuing:

"I also think it's nice to show that food doesn't have to be completely devoid of all kinds of microorganisms for us to eat it. There are microorganisms that can contribute positively to food," he says.

So far, the researchers have examined over 100 honey samples. The samples can be linked to geographical locations and information about the surrounding nature, such as the composition of the vegetation in nearby fields.

“Our bachelor's student, Linda Winnicki, has done a tremendous job. Together with Karl, she has isolated more than 2,500 yeast strains from the honey samples. She also began to characterise representative yeast species from the collection,” says Cecilia Geijer.

Understanding yeast can have a positive impact on society

But there is still a lot of work to be done. An initial analysis indicates that the collected honey can contain more than 100 different yeast species. Some of the species found have also been linked to honey and honeybees in other research studies, but the researchers also found completely new species that have not previously been described.

“A better understanding of yeast biodiversity in honey and in nature can have a major positive impact on our society's resilience to environmental change, increase food safety, and drive innovation in biotechnology and the food industry. There is a lot left to explore and develop in this research field, says Cecilia Geijer.

Further information about the Chalmers researchers

• The honey yeast will be used in the LiMiT research project. With a mission to reduce food waste