Montville Thomas J, Dengrove Rebecca, De Siano Tara, Bonnet Marcelo, Schaffner Donald W
Department of Food Science, Cook College, New Jersey Agricultural Experiment Station, Rutgers-the State University of New Jersey, 65 Dudley Road, New Brunswick, New Jersey 08901-8520, USA.
J Food Prot. 2005 Nov;68(11):2362-6. doi: 10.4315/0362-028x-68.11.2362.
The objective of this study was to determine the thermal resistance of spores of Bacillus anthracis and potential surrogates. The heat resistance of spores suspended in buffer (pH 7.0 or 4.5), milk, or orange juice was determined at 70, 80, and 90 degrees C. D-values for B. anthracis strains Sterne, Vollum, and Pasteur ranged from < 1 min at 90 degrees C to approximately 200 min at 70 degrees C and were lower under acidic than under neutral conditions. The D-values for B. anthracis spores fell within the range obtained for spores from eight strains of Bacillus cereus, Bacillus thuringiensis, Bacillus mycoides, and Bacillus subtilis. However, there were significant differences (P < 0.001) among the D-values of the strains. The z-values in pH 7.0 buffer and milk averaged approximately 10.5 degrees C and were not significantly different among strains (P < 0.05). The z-values in pH 4.5 buffer and orange juice averaged 12.9 and 13.9 degrees C, respectively, significantly (P < 0.05) higher than those obtained in milk or in pH 7.0 buffer. The significance of this difference was driven by large differences among a few strains. The z-values for B. anthracis strain Pasteur were twice as high in the acid media than in the neutral media. This study confirms that B. anthracis spores are not unusually heat resistant and that spores from validated Bacillus species are appropriate surrogates for thermal resistance studies.
本研究的目的是确定炭疽芽孢杆菌及其潜在替代菌芽孢的热阻。测定了悬浮于缓冲液（pH 7.0或4.5）、牛奶或橙汁中的芽孢在70、80和90℃时的耐热性。炭疽芽孢杆菌斯特恩菌株、沃勒姆菌株和巴斯德菌株的D值范围为90℃时小于1分钟至70℃时约200分钟，且在酸性条件下低于中性条件。炭疽芽孢杆菌芽孢的D值落在从蜡样芽孢杆菌、苏云金芽孢杆菌、蕈状芽孢杆菌和枯草芽孢杆菌的八个菌株获得的芽孢D值范围内。然而，各菌株的D值之间存在显著差异（P<0.001）。pH 7.0缓冲液和牛奶中的z值平均约为10.5℃，各菌株之间无显著差异（P<0.05）。pH 4.5缓冲液和橙汁中的z值分别平均为12.9℃和13.9℃，显著高于牛奶或pH 7.0缓冲液中的z值（P<0.05）。这种差异的显著性是由少数菌株之间的巨大差异驱动的。炭疽芽孢杆菌巴斯德菌株在酸性培养基中的z值是中性培养基中的两倍。本研究证实，炭疽芽孢杆菌芽孢的耐热性并非异常，且来自经过验证的芽孢杆菌属物种的芽孢是热阻研究的合适替代物。
