Which group of bacteria typically contains most of the pathogenic bacteria?

The group of bacteria that typically contains most of the pathogenic bacteria is the mesophilic category. Mesophilic bacteria thrive at moderate temperatures, generally between 20°C and 45°C (68°F and 113°F), which aligns closely with the temperature range of the human body (approximately 37°C or 98.6°F). This makes mesophilic bacteria well-suited to survive and proliferate in environments populated by humans and animals, where many foodborne pathogens are encountered.

Pathogenic bacteria such as Salmonella, Escherichia coli (E. coli), and Listeria monocytogenes are commonly mesophiles. Because these bacteria can grow and multiply rapidly in food stored or held within this temperature range, they pose a significant risk for foodborne illnesses.

In contrast, psychrophilic bacteria typically grow at lower temperatures, often found in refrigerated foods, which limits their association with foodborne pathogens. Thermophilic bacteria, while capable of thriving at high temperatures, are mostly involved in processes like composting, rather than being pathogens to humans. Facultative anaerobes are a diverse group that can grow in both oxygen-rich and oxygen-poor environments, but they may not necessarily be pathogenic despite some important foodborne pathogens