Research in the focus

New yeast species discovered in Braunschweig, Germany

Indigenous beech trees offer habitat for yeast threatened by climate change

Microbiologist Dr. Andrey M. Yurkov of the Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures (DSMZ) isolated a new yeast from tree sap in the Braunschweig districts of Stöckheim and Gartenstadt. In the spring seasons of 2016 and 2019, sap samples were taken from trees and shrubs (birch and beech trees, hornbeams, dogwood) that had been injured by annual pruning. It is well-known that the sugary sap of trees can host a wide range of microorganisms, including yeasts – but the variety of yeasts present in tree sap is as yet unknown. The yeast that Dr. Yurkov recently discovered bears the name Mrakia fibulata sp. nov (DSM 103931). “Species of the Mraki class tend to prefer cold habitats such as glaciers, ice and permafrost. Mrakia fibulata is the first of these yeasts to grow at a temperature of more than 20°C”, states the renowned mycologist.  

Climate change threatens microorganisms, too
Most yeasts present in tree sap are primarily known to live in cold habitats. For instance, yeasts of the Mrakia class had been isolated from polar (Arctic and Antarctic) and non-polar glaciers (high mountain ranges). These habitats are under great threat from global anthropogenic climate warming. One example is the Calderone glacier located in the Abruzzo region, one of Europe’s most southern glaciers. Two yeast cultures from this glacier have also been identified as Mrakia fibulata. Due to climate warming, the Calderone glacier has been melting for years, and scientists assume that it will disappear entirely over the next few years. As a consequence, the glacier’s psychrophilic (“cold-loving”) microorganisms will lose their natural habitat. “This makes it all the more gratifying that we were able to verify the presence of precisely these yeasts in moderate-climate Braunschweig”, says a delighted Andrey Yurkov. “It is particularly interesting that cold-loving microorganisms such as the newly discovered Mrakia fibulata as well as some related species have so far managed to survive climate change in Central Europe. This gives us reason for hope that they will continue to exist in nature, not just in bioresource collections such as the DSMZ.“ 

Biotechnological significance 
Microorganisms isolated from tree sap, especially yeasts, could be of great biotechnological importance. For instance, the yeast Phaffia rhodozyma produces a carotinoid (astaxanthin) that is added to fish food to intensify the red coloring of salmon meat. Species of the Mrakia class are able to ferment simple sugars and are currently being tested in the production of alcohol-free beer by the DSMZ’s cooperation partners at the University of Perugia in Italy. In addition, these yeasts are known to produce enzymes such as lipases and proteases used in water purification. 

Original publication
Yurkov, A.M., Sannino, C. & Turchetti, B. Mrakia fibulata sp. nov., a psychrotolerant yeast from temperate and cold habitats. Antonie van Leeuwenhoek (2019) 
doi:10.1007/s10482-019-01359-4