Pro-technological, probiotics, pathogens and spoilage microorganisms associated with food and their origin and role. Microorganisms as a source of natural antimicrobials for the food industry. Microorganisms as indicators of food quality and safety. Sources of microbial contamination (air, soil, water, plants, animal, human). Microorganisms responsible for foodborne diseases: Escherichia coli, Salmonella spp., Shigella spp., Yersinia enterocolitica, Campylobacter jejuni, Listeria monocytogenes, Clostridium botulinum Clostridium perfringens, Staphylococcus aureus. Bacillus cereus. General characteristics of filamentous fungi, mycotoxin production. Several case studies.