The resistance formation of spores in general and of Bacillus atrophaeus in particular has long been the focus of science in the bio-defense, pharmaceutical and food industries. In the food industry, it is used as a biological indicator (BI) for the evaluation of the inactivation effects of hydrogen peroxide in processing and end packaging lines’ sterilization. Defined BI resistances are critical to avoid false positive and negative tests, which are salient problems due to the variable resistance of currently available commercial BIs. Although spores for use as BIs have been produced for years, little is known about the influence of sporulation conditions on the resistance as a potential source of random variability. This study therefore examines the dependence of spore resistance on the temperature, pH and partial oxygen saturation during submerged production in a bioreactor. For this purpose, spores were produced under different sporulation conditions and their resistance, defined by the D-value, was determined using a count reduction test in tempered 35% liquid hydrogen peroxide. The statistical analysis of the test results shows a quadratic dependence of the resistance on the pH, with the highest D-values at neutral pH. The sporulation temperature has a linear influence on the resistance. The higher the temperature, the higher the D-value. However, these factors interact with each other, which means that the temperature only influences the resistance when the pH is within a certain range. The oxygen partial pressure during sporulation has no significant influence. Based on the data obtained, a model could be developed enabling the resistance of BIs to be calculated, predicted and standardized depending on the sporulation conditions. BI manufacturers could thus produce BIs with defined resistances for the validation of sterilization effects in aseptic packaging/filling lines for the reliable manufacture of shelf-stable and safe food products.

中文翻译：

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沉水培养后孢子形成条件对萎缩芽孢杆菌孢子抗H2O2灭活的影响

孢子的抗性形成，特别是萎缩芽孢杆菌的抗性，长期以来一直是生物防御、制药和食品工业科学的焦点。在食品工业中，它被用作评估过氧化氢在加工和最终包装线灭菌中的灭活效果的生物指示剂 (BI)。定义的 BI 电阻对于避免假阳性和阴性测试至关重要，这是由于当前可用的商业 BI 的可变电阻而导致的突出问题。尽管用作 BI 的孢子已经生产多年，但关于孢子形成条件对作为随机变异性潜在来源的抗性的影响知之甚少。因此，本研究考察了孢子抗性对温度的依赖性，生物反应器中水下生产过程中的 pH 值和部分氧饱和度。为此，孢子在不同的孢子形成条件下产生，它们的抵抗力（由 D 值定义）是使用在调和的 35% 液体过氧化氢中进行的计数减少测试来确定的。测试结果的统计分析显示电阻与 pH 值呈二次关系，在中性 pH 值下 D 值最高。孢子形成温度对电阻具有线性影响。温度越高，D 值越高。但是，这些因素相互影响，这意味着只有当pH值在一定范围内时，温度才会影响电阻。孢子形成过程中的氧分压没有显着影响。根据获得的数据，可以开发一个模型，能够根据孢子形成条件计算、预测和标准化 BI 的抗性。因此，BI 制造商可以生产具有定义电阻的 BI，用于验证无菌包装/灌装线中的灭菌效果，从而可靠地制造货架稳定和安全的食品。