Centre Technique pour la Conservation des Produits Agricoles, Unité Expertise dans la Maîtrise du Risque Industriel en Thermorésistants Sporulés (EMaiRIT'S), UMT Qualiveg 2, 449 Avenue Clément-Ader, 84911, Avignon, France; Univ Brest, INRAE, Laboratoire Universitaire de Biodiversité et Écologie Microbienne, F-29000, Quimper, France.
Univ Brest, INRAE, Laboratoire Universitaire de Biodiversité et Écologie Microbienne, F-29000, Quimper, France.
Food Microbiol. 2022 Sep;106:104055. doi: 10.1016/j.fm.2022.104055. Epub 2022 May 4.
Group I Clostridium botulinum and Clostridium sporogenes are physiologically and genetically closely related. Both are widely distributed in the environment and can cause foodborne botulism. In this work, a physiological study was conducted with 37 isolates from spoiled canned food and five referenced strains of C. sporogenes (three isolates) and Group I C. botulinum (two isolates). Growth limits of vegetative cells were established as a function of pH and NaCl concentration in PYG modified medium (PYGm) at 30 °C for 48 days. The heat resistance of the spores was studied for 2 min and 10 min at 102 °C and 110 °C. This physiological study (pH, NaCl growth limits and heat resistance) allowed the selection of 14 isolates of C. sporogenes (twelve isolates) and Group I C. botulinum (two isolates) representative of the diversity found. This panel of 14 selected isolates (11 isolated from spoiled canned food and three reference strains), were whole genome sequenced, but no association of physiological and genetic characteristics could be detected. Finally, we studied the ability of spores to germinate and grow from 5 isolates (four C. sporogenes and one Group I C. botulinum), under stress conditions generated by pH and NaCl following a low intensity heat treatment. The accumulation of these 3 stresses creates synergies that will strongly reduce the probability of spore growth in pH and salt conditions where they usually proliferate. The effect is progressive as the conditions become drastic: the number of decimal reduction observed increases translating a probability of growth which decreases. This study provides a better understanding of the behaviour of C. sporogenes and Group I C. botulinum isolates and shows how the combination of pH, NaCl and heat treatment can help prevent or minimise foodborne botulism outbreaks.
I 组肉毒梭菌和生孢梭菌在生理和遗传上密切相关。它们广泛分布于环境中，可引起食源性肉毒中毒。在这项工作中，对 37 株来自变质罐头食品的分离株和 5 株参考的生孢梭菌（3 株分离株）和 I 组肉毒梭菌（2 株分离株）进行了生理研究。在 30°C 下，用 PYG 改良培养基（PYGm）在 48 天内确定了营养细胞的生长极限，作为 pH 和 NaCl 浓度的函数。在 102°C 和 110°C 下，研究了孢子的耐热性，时间分别为 2 分钟和 10 分钟。这项生理研究（pH、NaCl 生长极限和耐热性）选择了 14 株生孢梭菌（12 株分离株）和 I 组肉毒梭菌（2 株分离株），代表了发现的多样性。该面板由 14 个选定的分离株组成（11 个分离株来自变质罐头食品和 3 个参考菌株），对其进行了全基因组测序，但未检测到生理和遗传特征之间的关联。最后，我们研究了 5 株分离株（4 株生孢梭菌和 1 株 I 组肉毒梭菌）的孢子在低强度热处理后，由 pH 和 NaCl 产生的应激条件下的发芽和生长能力。这些 3 种应激的积累会产生协同作用，强烈降低它们通常在 pH 和盐条件下增殖的孢子生长的可能性。随着条件变得越来越苛刻，这种影响是渐进的：观察到的十进制减少数量增加，翻译的生长概率降低。这项研究更好地了解了生孢梭菌和 I 组肉毒梭菌分离株的行为，并展示了 pH、NaCl 和热处理的组合如何有助于预防或最小化食源性肉毒中毒的爆发。
