The smell of those funky cheese allows germs to ‘talk’ and feed each other.

Fungi and bacteria communicate and feed with each other using key volatile compounds to cook the cheese. Sincerely: Adam Detour

Researchers at Tufts University have found that the funky smell different from cheese is in a way that fungi communicate with bacteria, and what they’re saying has a lot to do with the delicious variety of flavor that cheese has to offer. . The research team found that the common bacteria needed to cook the cheese could sense and react to compounds produced by the fungus in the veins and released into the air, thereby increasing the growth of some species of bacteria. The composition of the cheese microbiome-forming bacteria, yeast, and fungi is critical to the taste and quality of cheese, so finding out how it can be controlled or modified adds science to the art of cheese making.

Published in, Search Environmental microbiology, Also provides a model for the understanding and modification of other economically and clinically important microbiomes such as soil or gastrointestinal tract.

“Humans have appreciated the diverse fragrances of cheese for hundreds of years, but how those fragrances affect the biology of the cheese microbiome was not studied,” said Benjamin Wolfe, organist at Tufts University and the School of the Arts Professor of Science and author of the same study. “Our latest findings suggest that cheese germs can use these fragrances to dramatically alter their biology, and the importance of the findings extends to other areas beyond cheese as well.”

Many germs produce airborne chemical compounds called volatile organic compounds, or VOCs, as they interact with their environment. One widely recognized microbial VOC is geosmin, which is excreted by soil microbes and can often be sniffed after heavy rains in the forests. When bacteria and fungi grow on ripening beans, they secrete enzymes that break down amino acids to produce acids, alcohols, aldehydes, amines, and various sulfur compounds, while other enzymes break down fatty acids. Actors produce methyl ketone and secondary alcohols. All of those organic products contribute to the taste and aroma of the cheese and that is why Camembert, Blue Cheese and Limburger have their signature scent.

Researchers at Tufts found that VOC not only contributes to the sensory experience of cheese, but provides a way to “feed” and communicate bacteria in the cheese microbiome with fungi. By combining 16 different mango cheese bacteria with 5 different cheese cheese molds, the researchers found that the fungus caused reactions in bacteria ranging from strong stimulation to strong inhibition. A bacterial species, Vibrio casei, responded rapidly to the presence of VOCs emitted by all five of the fungi. Other bacteria, such as Cycrobacter, grew only in response to one of the fungi (galactomyces), and the number of two common cheese bacteria decreased significantly when exposed to VOCs produced by galactomy.

Researchers found that VOCs changed the expression of many genes in bacteria, including genes that affect nutrient metabolism. A metabolic mechanism was enhanced, called glyxylate shunt, allowing bacteria to use more simple compounds as “food” when more complex sources such as glucose are unavailable. In fact, they enabled some VOCs to better “eat” the bacteria and use them as sources of energy and growth.

“Post-doctoral scholar in the Department of Biology at Tuffs University and the first author of the study, Casey Cosetta, said,” Bacteria are actually able to eat what we smell. “” This is important because the cheese itself provides very little in the form of easily metabolized sugars such as glucose. With VOCs, fungi are actually providing a useful aid to help bacteria flourish. ”

This research has direct implications for cheese producers around the world. Many VOCs are released into the air as you age in a cheese cave. These VOCs can affect how neighboring chiku develop by promoting or inhibiting the growth of specific germs, or by changing how bacteria produce other biological products that add to flavor. A better understanding of this process may enable cheese producers to manipulate the environment of VOCs to improve the flavors of quality and diversity.

The implications of research can extend even further. “Now that we know that airborne chemicals can control the composition of microbiomes, we can start thinking about how to control the composition of other microbiomes, e.g. soil quality and crop production in agriculture To improve and to help manage diseases affected by diseases in medicine. Hundreds of species of bacteria in the body, “Wolff said.

Cheese: New insights into new age food

more information:
Casey M. Cosetta et al, Fungal Volatile Mediated Cheese Rind Microbiome Assembly, Environmental microbiology (2020). DOI: 10.1111 / 1462-2920.15223

Provided by Tufts University

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