Final answer:
Pathogenic bacteria, including Bacillus cereus, Campylobacter jejuni, and strains of Escherichia coli among others, cause the greatest harm in the food industry and are closely monitored by health authorities to prevent foodborne illnesses.
Step-by-step explanation:
The bacteria that cause the greatest harm in the food industry are pathogenic bacteria. These include strains such as Bacillus cereus, Campylobacter jejuni, Clostridium spp., pathogenic strains of Escherichia coli, Listeria monocytogenes, Salmonella spp., Shigella spp., Staphylococcus aureus, Vibrio spp., and Yersinia spp. Furthermore, the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) require routine bacteriological testing to ensure food safety and protect the public from food-borne illnesses caused by these harmful bacteria.