Specific endospore formers have become important contaminants in industrial food processing. The direct or indirect soil route of contamination or dispersal is the start of events or processes in the agrofood chain that eventually leads to important problems or concerns for food safety and/or quality. Three important food sectors are discussed in this paper. In the dairy sector, Bacillus cereus, the most important pathogen or spoilage organism in this sector, and Clostridium tyrobutyricum, the most important spoiler in certain cheeses, both contaminate pasteurized milk through the faecal and/or (at least for B. cereus) the direct soil route. In the fruit juice industry, Alicyclobacillus acidoterrestris, present on raw fruits, has become a major quality-target organism. In the ready-to-eat food sector, B. cereus and other aerobic endospore formers are introduced via vegetables, fruits, or herbs and spices, while anaerobic spore formers like nonproteolytic Clostridium botulinum and Clostridium estertheticum pose safety and spoilage risks in chilled packaged foods, respectively. 1. Introduction There is a clear association between soil-borne endospore forming bacteria and food contamination. The spore formers implicated belong both to the strictly anaerobic (“the clostridia”) and to the aerobic (the genus Bacillus and related genera) phylogenetic groups of microorganisms. Several reasons can be proposed to explain this phenomenon, and most are related to some general characteristics of the spores, which are formed at the end of the growth phase within the vegetative mother cell acting as sporangium (hence, endospores) and released in the environment as survival structures (Figure 1). These are (1) their ubiquitous presence in soil, (2) their resistance to heat in common industrial processes such as pasteurization, (3) the adhesive characters of particular spores that facilitate their attachment to processing equipment, and (4) their ability to germinate and grow in favorable conditions [1]. Several spore formers either need or tolerate specific conditions for germination and growth, which all can occur in food even in combination, such as low or high temperatures and anaerobic or acidophilic conditions. The concerted characteristics of spores and vegetative cells of particular soil-borne species make them potential sole surviving and growing contaminants in specific industrially processed foods. Some of them seem even to be of more recent concern, which might be the result of increasing tolerance, adaptation, or resistance of spores or vegetative cells of
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