The Conversation Spain
Micro goblins: the microorganisms that help us celebrate Christmas
At Christmas, a time of joy and happiness, each person has their preferences: Three Wise Men or Santa Claus? Portal of Bethlehem or Christmas tree? Cava or cider? Better a little bit of everything. And what does microbiology have to do with all this? In a previous article we talked about the Halloween holiday and microorganisms. Now let’s see what role these play in the celebration of Christmas, for better and for worse. What do we find under the Christmas tree When we talk about the Christmas tree, we almost always imagine a fir tree. These are initially raised in nursery greenhouses and, when they reach a suitable size, are transplanted into the field. The area of the soil surrounding the root of the tree is known as the rhizosphere. For fir trees to grow healthy and reach the proper size, it is essential that appropriate relationships are established with the microorganisms in the rhizosphere. Areas where fir trees grow tend to have soils poor in nitrogen, which limits their growth. There is a group of microorganisms that are maintained throughout the life of the fir, from nurseries until they reach their maximum development. They contribute nitrogen to the tree and also other substances that promote its growth. The beneficial microorganisms in the rhizosphere also help fight against pathogens that can cause diseases to the tree. In addition, they allow you to better tolerate other problems, such as soil salinity or heat, so, in addition to gifts, under the Christmas tree are the microorganisms that make it so beautiful. Do we pack the gifts? We can wrap our gifts with shiny paper or put them in bags with Christmas pictures. In any case, what do we need to get paper? You can imagine! Without trees there would be no paper. Most trees need root-associated fungi in order to grow, as they help them obtain the nutrients they need. This way we will have wood, which will later be processed to make paper.Once we have opened the gifts, the beautiful paper goes to the container. The microorganisms will help to recycle this and other waste, returning the nutrients to the environment so that the cycle begins again. Warm chocolate or in chocolates and sweets Without microorganisms we would not have chocolate. That would kill my Christmas spirit! We need microscopic mushrooms in two stages of chocolate production. On the one hand, they are essential for the cacao tree to grow properly. They form a symbiosis: it provides them with the sugars that it manufactures through photosynthesis, while they help it obtain water and nutrients from the soil. Second, cocoa beans are very bitter and acidic. For them to lose that bad taste, they must be fermented by two fungi: Candida krusei and Geotrichum sp. Christmas dinner would not be the same without microorganisms Wine, Champagne, beer … To produce all these drinks it is necessary for a yeast, (Saccharomyces cerevisiae), to carry out the alcoholic fermentation of sugars. Some non-alcoholic drinks, such as soft drinks cola, contain citric acid. To produce it, you need a microscopic fungus, Aspergillus niger, and bacteria and fungi are involved in the production of many of the usual snacks: cheese, pickles (pickles), olives, sausages, etc. On the other hand, in bread, biscuits, cakes, puddings and all bakery and pastry products are made using “baker’s yeast”, which makes the dough rise. To obtain many other products that we use in our recipes, such as yogurt or soy sauce, microorganisms are also involved, and at the end: coffee. Also here they have something to do? Yes, since a fundamental stage in the processing of coffee beans is fermentation. Lactic acid bacteria play an important and positive role in this process. What do the reindeer from Santa’s sleigh and the camels of the Magi eat In the frozen tundra, reindeer feed on lichens, especially the so-called “reindeer lichen” (Cladonia rangiferina). They abound in the North Pole and thanks to them, these animals manage to survive in the Arctic zone. Lichens are the result of the symbiosis between a fungus and an alga (or sometimes a cyanobacteria). It is the turn of the camels, which have the stomach divided into 3 compartments. These feed on herbs and can even eat prickly plants, thanks to the shape of their lips. This time it is in the ruminal microbiota, whose main function is to digest plant food, where bacteria, protozoa, archaea and fungi are found.These microorganisms help camels to obtain all possible nutrients from low-quality food nutritious and difficult to digest. Thus, they may have the strength to make their long journey to reach Bethlehem. Animals that provide heat to the Portal de Belén In the Portal de Belén we have more animals: the mule and the ox, which is a ruminant.Digestion in the rumen is an example of mutualism between animals and intestinal microorganisms. Ruminants consume cellulose-rich grass, leaves, and twigs. For its part, the rumen is home to large populations of protozoa and bacteria that contribute to digestion. These convert cellulose, starch, and other nutrients into carbon dioxide, hydrogen gas, methane, and low-molecular-weight organic acids. The carbon dioxide and methane produced in the rumen by the fermentation of methanogens are expelled to the outside. The release of methane and carbon dioxide generates heat, but it also has its risks. Mischievous little goblins that can spoil Christmas for us Many of the holiday meals are prepared in advance. That makes microbial contamination more likely. In other cases, the size of the cooked pieces makes it difficult for the center of the food to reach a sufficient temperature to kill bacteria. Turkeys often have Clostridium perfringens in their intestines. They must be removed carefully, and make sure that temperatures above 75ºC are reached inside when cooking. After the binge, the leftovers should be stored in small portions in the fridge. Poisoning by this microorganism is quite common and its effects can last for weeks.Phytophthora infestans is a microorganism that affects potato crops. It can destroy entire crops. As a curious fact, it was responsible for “the potato famine”, which caused the emigration of thousands of Irish to the US at the end of the 19th century. Salmonella, Listeria and other microorganisms can also leave a bad memory of Christmas meals. To avoid this, it is important to follow hygienic measures when preparing food. At the end of the feast, leftover food should not be left on the table and at room temperature for long. Ideally, divide it into small portions (to cool down before) and store it in the fridge. In this way we will avoid food poisoning. Micro-goblins of 2021 During 2020, microorganisms in general and viruses in particular have radically changed our lives. The covid-19 pandemic has affected us in many ways. We will miss more than ever those who have left us and family and friends will be lacking in our celebrations. Many of the traditions, such as the Three Kings parade or visits to the nativity scenes, will have to be suspended or done virtually, and this Christmas will definitely be different. The main thing is to continue to maintain precautions. Hopefully in 2021 the good microorganisms will regain the limelight and “the coronavirus” will become the ghost of last Christmas. Until this happens, take care of yourself and others. Merry Christmas and Happy 2021! This article was originally published on The Conversation. Read the original.María Teresa Tejedor Junco does not receive a salary, nor does she work as a consultant, nor does she own shares, nor does she receive financing from any company or organization that can benefit from this article, and has declared that she lacks relevant links beyond the academic position aforementioned.