Parageobacillus and Geobacillus spp.: From Food Spoilage to Beneficial Food Applications

The genera Parageobacillus and Geobacillus comprise thermophilic, spore-forming bacteria. The extraordinary heat resistance of their spores, together with their ability to form biofilms and produce thermostable enzymes, makes them a relevant cause of spoilage in shelf-stable, heat-treated products like dairy and canned foods. However, these same biological traits offer valuable opportunities for the food industry. In this context, the purpose of this review is to describe the challenges posed by (Para)Geobacillus spp. as food spoilage agents, while also highlighting their existing and prospective applications in the food industry. In terms of food safety, G. stearothermophilus spores are used as biological indicators in commercially available tests to detect antibiotic residues in food within a few hours. Additionally, (Para)Geobacillus can be exploited for the fermentation of agri-food residues to produce high-value compounds such as biofuels, food ingredients and technological adjuvants, and compost. Their thermostable enzymes-such as amylases, xylanases, L-arabinose isomerases, β-galactosidases, lipases, proteases, and L-asparaginases-have potential applications in food processing and ingredient production. However, several challenges persist, including limited knowledge on genetic diversity, physiology, and metabolism, as well as low yields of biomass and target compounds. These issues reinforce the need for further studies to unlock their full potential.