Podrzaj Lucija, Burtscher Johanna, Küller Franziska, Domig Konrad J
Institute of Food Science, University of Natural Resources and Life Sciences Vienna (BOKU), 1190 Vienna, Austria.
Austrian Competence Centre for Feed and Food Quality, Safety and Innovation (FFoQSI GmbH), Technopark 1C, 3430 Tulln, Austria.
Microorganisms. 2020 Nov 22;8(11):1836. doi: 10.3390/microorganisms8111836.
, a Gram-positive, anaerobic, spore-forming bacterium, is considered as one of the main causative agents for spoilage of hard and semihard cheeses. Growth of in cheese is critically influenced by ripening temperature and time, pH, salt and lactic acid concentration, moisture and fat content, and the presence of other microorganisms. Previous studies revealed high intraspecies diversity of strains and variable tolerance toward pH, temperatures, and salt concentrations. These findings indicate that strain-dependent characteristics may be relevant to assess the risk for cheese spoilage if clostridial contamination occurs. In this study, we aimed to compare the phenotypes of 12 strains which were selected from 157 strains on the basis of genotypic and proteotypic variability. The phenotypic analysis comprised the assessment of gas production and organic acid concentrations in an experimental cheese broth incubated at different temperatures (37, 20, and 14 °C). For all tested strains, delayed gas production at lower incubation temperatures and a strong correlation between gas production and the change in organic acid concentrations were observed. However, considering the time until gas production was visible at different incubation temperatures, a high degree of heterogeneity was found among the tested strains. In addition, variation among replicates of the same strain and differences due to different inoculum levels became evident. This study shows, that, among other factors, strain-specific germination and growth characteristics should be considered to evaluate the risk of cheese spoilage by .
作为一种革兰氏阳性、厌氧、产芽孢细菌，被认为是硬质和半硬质奶酪变质的主要致病因素之一。奶酪中的生长受到成熟温度和时间、pH值、盐和乳酸浓度、水分和脂肪含量以及其他微生物存在的严重影响。先前的研究揭示了菌株的种内高度多样性以及对pH值、温度和盐浓度的不同耐受性。这些发现表明，如果发生梭菌污染，菌株依赖性特征可能与评估奶酪变质风险相关。在本研究中，我们旨在比较基于基因型和蛋白质型变异性从157株菌株中选出的12株菌株的表型。表型分析包括在不同温度（37、20和14°C）下孵育的实验奶酪肉汤中气体产生和有机酸浓度的评估。对于所有测试菌株，在较低孵育温度下气体产生延迟，并且观察到气体产生与有机酸浓度变化之间存在强相关性。然而，考虑到在不同孵育温度下可见气体产生的时间，在测试菌株中发现了高度的异质性。此外，同一菌株重复之间的差异以及由于接种水平不同而产生的差异变得明显。本研究表明，在评估由引起的奶酪变质风险时，除其他因素外，应考虑菌株特异性发芽和生长特征。
