Physical Treatments to Control Clostridium botulinum Hazards in Food

Abstract

Clostridium botulinum produces Botulinum neurotoxins (BoNTs), causing a rare but potentially deadly type of food poisoning called foodborne botulism. This review aims to provide information on the bacterium, spores, toxins, and botulisms, and describe the use of physical treatments (e.g., heating, pressure, irradiation, and other emerging technologies) to control this biological hazard in food. As the spores of this bacterium can resist various harsh environmental conditions, such as high temperatures, the thermal inactivation of 12-log of C. botulinum type A spores remains the standard for the commercial sterilization of food products. However, recent advancements in non-thermal physical treatments present an alternative to thermal sterilization with some limitations. Low- (<2 kGy) and medium (3–5 kGy)-dose ionizing irradiations are effective for a log reduction of vegetative cells and spores, respectively; however, very high doses (>10 kGy) are required to inactivate BoNTs. High-pressure processing (HPP), even at 1.5 GPa, does not inactivate the spores and requires heat combination to achieve its goal. Other emerging technologies have also shown some promise against vegetative cells and spores; however, their application to C. botulinum is very limited. Various factors related to bacteria (e.g., vegetative stage, growth conditions, injury status, type of bacteria, etc.) food matrix (e.g., compositions, state, pH, temperature, aw, etc.), and the method (e.g., power, energy, frequency, distance from the source to target, etc.) influence the efficacy of these treatments against C. botulinum. Moreover, the mode of action of different physical technologies is different, which provides an opportunity to combine different physical treatment methods in order to achieve additive and/or synergistic effects. This review is intended to guide the decision-makers, researchers, and educators in using physical treatments to control C. botulinum hazards.

Foodborne Clostridioides Species: Pathogenicity, Virulence and Biocontrol Options

“…Toxin A, toxin B, binary toxin (CDT) C. difficile, colonocyte death and colitis, CDI extra-intestinal effects [5], C. botulinum [26] Toxins A (enterotoxin) and B (potent cytotoxin) act as glucosyltransferases Toxigenic C. difficile influences colonic tumorigenesis [27] CDT affects ADP-ribosyltransferase [5,28], inhibits the protein actin, damaging the cytoskeleton of GIT cells [29] Induces necrosis in epithelial cells [28] Spores Antibiotic resistance, germination in GIT environment [30] Biocidal resistance-survival in food production environments Germination of C. difficile leads to intestinal inflammation, perforation, toxic megacolon and pseudomembranous colitis [29] C. botulinum spores are one of the most heat-resistant pathogenic spores [31], exosporium confers biocide resistance, sporulation and germination of C. botulinum produces exotoxins e.g., neurotoxins…”

“…The exosporium is absent in C. perfringens (where the outermost layer is the spore coat) [33], but also present in C. botulinum where it is believed to confer chemical resistance and protection to the infectious spore [57]. The spores of C. botulinum are extremely heat resistant; C. botulinum spore inactivation is the target for thermal processing of low-acid canned (pH > 4.6) food items [31]. Additionally, spores can survive milk pasteurisation, and contamination from animal faecal matter raises the risk of their presence in milk and dried milk products.…”

“…Neurotoxigenic C. botulinum strains are also classified according to the type of toxin they produce. Currently, nine types of BT neurotoxin strains have been identified, namely, A, B, C, D, E, F, G, H, and X [31]. Botulinum A toxins are relatively heat sensitive and can be destroyed at pasteurization temperatures (63 • C, 30 min), whereas toxin B appears more resistant to this treatment [66].…”

“…Although C. botulinum foodborne illness is rare, the botulism toxin causes a severe form of food poisoning with a high mortality rate at very low levels of toxin concentration [26]. Indeed, C. botulinum and its toxins have been detected in food as vegetative and spore forms [31]. Toxin types A and B are associated with C. botulinum disease, with soil contamination of vegetables and meat products acting as vehicles of transmission [26].…”

Exploring the genetic background of the botulism neurotoxin BoNT/B2 in Spain

“…Proteolytic C. botulinum group I forms spores strongly resistant to heat and is primarily responsible for human botulism ( 2 ). The BoNT/C, /D, /C/D, and /D/C types mostly affect domestic and wild birds and cattle, but have zoonotic potential ( 6 ). The presence of bont -related sequences in non-clostridial strains ha been detected in the genomes of the Weisenella oryzae ( bont /Wo or bont /I), Enterococcus faecalis ( bont /J or ebont /F or bont /En), of Chryseobacterium piperi ( Cp 1), Paraclostridium bifermentans (the paraclostridial mosquitocidal protein 1, PMP1), but no consensus has been reached on their validity ( 3 , 7 ).…”