Which type of bacteria is harmless and helps the body break down food and protect against infection?

Nonpathogenic bacteria are those that are harmless and, in many cases, beneficial to the body. They play a vital role in various bodily functions, including the digestion of food in the gastrointestinal tract. These bacteria aid in the breakdown of complex food substances into simpler forms that can be easily absorbed by the body. Additionally, nonpathogenic bacteria help protect against infections by competing with pathogenic bacteria for resources and space, thereby reducing the likelihood of harmful bacteria establishing themselves in the body.

In contrast, pathogenic bacteria cause diseases and infections. Gram-negative and aerobic refer to specific characteristics of bacteria but do not inherently define whether they are harmful or beneficial. Gram-negative bacteria are characterized by their cell wall structure and may include both pathogenic and nonpathogenic species. Aerobic bacteria require oxygen for growth and can also be either harmful or harmless, depending on the specific species. Thus, nonpathogenic is clearly the type of bacteria that supports health and wellbeing by contributing to digestion and providing protection from infections.