Microbiology and Yeast Cell Fermentation Photo from Flickr.com What are Microbes? Microbes: Living things that must be greatly magnified to be seen. They include bacteria, fungi and viruses. What is Microbiology? • Microbiology is the study (logy) of very small (micro) living (bio) things. One of the most famous microbiologist is Louis Pasteur. Pasteur performed experiments that proved that microbes cause fermentation. What is fermentation? Fermentation: A process of growing microorganisms (microbes) to produce various chemicals or pharmaceutical compounds. Fermentation of microbes is how most Biotechnology companies products such as enzymes and medicines. Definition from: Mapping your Future: Exploring Careers in Biomanufacturing What is yeast? • Yeast: A general term for single-celled fungi that reproduce by budding. Yeast cells under the microscope. Yeast cells budding. Some yeast can ferment carbohydrates (starches and sugars) and thus are important in brewing and baking. Definition from: Mapping your Future: Exploring Careers in Biomanufacturing What do yeast cells need to grow and survive? Carbon (sugar source) Nitrogen (protein source) Vitamins Yeast feeds on sugar from a variety of sources, including fruit, grain, nectar and molasses. How DID Biotech first use microbes? Around 4000 BC, Egyptians used the living organism yeast to make bread. Airborne wild yeast accidentally got their bread dough, causing it to rise. How does yeast affect the bread making process? Bread Dough is made with flour which contains nutrients and sugar that the yeast cells digest. When the yeast eats the sugar, it gives off 2 waste (by) products: The chemical reaction is written as follows: YEAST + SUGAR = CARBON DIOXIDE & ALCOHOL How do the by-products of yeast fermentation influence the bread making process? The carbon dioxide is what makes the dough rise and give it a light, airy texture. The alcohol evaporates during baking and gives off that wonderful aroma of baking bread. The baking destroys the yeast.