Which of the following are included in biochemical tests for identifying bacteria?

Biochemical tests for identifying bacteria primarily focus on assessing various metabolic activities and fermentation capabilities of the organisms. These tests analyze how bacteria utilize different substrates and their by-products, such as gases or acids, during growth. For instance, tests can evaluate whether a bacterium can ferment sugars or produce gas, which are key indicators in differentiating bacterial species.

The strength of biochemical tests lies in their ability to provide insights into the physiological characteristics of bacteria. These characteristics are instrumental in species identification and understanding bacterial behavior within specific environments.

Other methods, such as microscopic examination or culturing on selective media, play essential roles in the overall identification process. However, they do not provide the same depth of information about metabolic pathways that biochemical tests do. Furthermore, testing for the presence of specific antibodies is a different approach associated more with serological testing rather than direct biochemical identification.

Thus, the focus on fermentation and metabolic activity is a cornerstone of biochemical tests, making it the correct answer in identifying bacteria.