What is a common characteristic of spoilage bacteria?

Spoilage bacteria are primarily known for their ability to cause food to become unfit for consumption. The growth of these bacteria on food can lead to unpleasant changes in taste, smell, and texture, making the food undesirable and potentially hazardous to health. This type of bacteria breaks down food substances, producing byproducts that may render the food inedible. Thus, understanding this characteristic is crucial for food safety and handling practices.

In contrast, the other characteristics listed do not accurately define spoilage bacteria. For example, while some bacteria can be harmful, not all spoilage bacteria cause illness; their main impact is on the quality of the food rather than directly harming health. Additionally, some bacteria involved in fermentation or promoting gut health are actually beneficial. Hence, the defining feature of spoilage bacteria is their role in making food unfit for consumption.