What is the process of breakdown of a substance by microorganisms, often producing fizzing and heat?

The process described in the question—breakdown of a substance by microorganisms that results in fizzing and heat—is known as fermentation. This biological process involves the conversion of sugars into acids, gases, or alcohol using microorganisms, primarily yeasts and bacteria. During fermentation, the metabolic activities of these microorganisms generate energy, leading to the production of byproducts like carbon dioxide, which is responsible for fizzing, and heat, due to the exothermic nature of the reaction.

Fermentation is widely utilized in various food and beverage production processes, such as bread-making, brewing beer, and fermenting yogurt. These applications leverage not only the flavor changes that occur but also the preservation qualities that fermentation provides.

In contrast, while digestion also involves breaking down substances, it refers more specifically to the biochemical process occurring in the body where complex food items are converted into simpler nutrients. Metabolism encompasses all chemical reactions within an organism, including both catabolic processes (like fermentation) and anabolic processes, making it too broad for this specific question. Decomposition involves the breakdown of organic matter through various organisms, primarily leading to nutrient recycling in ecosystems, and is not characterized by the fizzing and heat mentioned. Therefore, fermentation is the correct answer, as it specifically illustrates the breakdown