UNIL researchers have uncovered ancient signs of bacterial domestication in Swiss cheeses, enhancing our understanding of microbiology and its impact on food preservation and sustainability.
In a groundbreaking discovery, researchers at the University of Lausanne (UNIL) have uncovered evidence of ancient bacterial domestication in the production of traditional Swiss cheeses like Gruyère, Emmental and Sbrinz.
This pioneering research, published in Nature Communications, offers a fresh perspective on how human societies have harnessed microbes to improve food preservation and safety for millennia.
A Historical Parallel to Plant and Animal Domestication
The domestication of plants and animals is well-documented, marking a pivotal era in human history as populations transitioned from hunter-gatherer societies to settled agricultural communities.
However, the domestication of microbes, particularly bacteria, has remained largely elusive due to their microscopic size and the absence of a fossil record.
While previous studies have shed light on the domestication of yeasts, a team led by Vincent Somerville, a former doctoral student in Philipp Engel’s team, and co-directed by Philipp Engel, an associate professor at UNIL’s Department of Fundamental Microbiology, and Florent Mazel, a senior scientist in the Engel lab, aimed to explore the domestication of bacteria involved in cheese production.
Their efforts culminated in the revelation that the bacteria used in classic Swiss cheese recipes exhibit signs of domestication akin to those seen in livestock and crops.
Unveiling the Ancient Process
Domestication typically involves selectively breeding species over generations to enhance desirable traits, such as increased nutritional quality or docility. Engaging in such practices with microbes has profound implications, especially in food preservation.
“This is the case with fermentation, which converts sugars into acids, protects against the proliferation of undesirable microbes and therefore enables food to be preserved for longer,” Engel said in a news release.
Fermentation, a technique with roots tracing back to the Neolithic period around 10,000 years ago, leverages microorganisms like yeast for brewing beer and wine and bacteria for making cheese. Recognizing the ancient origins of microbial fermentation offers vital context to Engel’s assertion.
Swiss Cheeses at the Forefront
In collaboration with Agroscope, Switzerland’s center for agronomic and food research, the Lausanne team delved into a 50-year-old collection of bacterial strains used in Gruyère, Emmental and Sbrinz cheese production.
“These cultures, also called ‘cheese starter cultures,’ were partially reactivated to create some sort of laboratory mini cheeses,” Somerville said in the news release.
The researchers analyzed the genetic and phenotypic attributes of over 100 bacterial isolates and nearly 1,000 samples, uncovering low genetic diversity and high trait stability over the examined period. These findings pointed towards an ancient adaptation process,.
“The temporal concordance between the dating of the micro-organisms and the archaeological history of this fermented food was quite unexpected,” added Mazel.
Implications and Future Directions
The implications of this study extend far beyond Swiss cheeses. Future research may compare cheeses from various global regions or investigate the bacterial communities used in other fermented products like kefir.
“A better understanding of bacterial domestication will enable us to optimize the characteristics of these microbiota, improve the use of this process and make it a more sustainable method of food storage,” Mazel added.