Dipartimento di Biotecnologie, Università degli Studi di Verona, Strada le Grazie 15, 37134 Verona, Italy.
Appl Environ Microbiol. 2011 Apr;77(8):2817-22. doi: 10.1128/AEM.02531-10. Epub 2011 Mar 4.
This study evaluated the influence of parameters relevant for cheese making on histamine formation by Streptococcus thermophilus. Strains possessing a histidine decarboxylase (hdcA) gene represented 6% of the dairy isolates screened. The most histaminogenic, S. thermophilus PRI60, exhibited in skim milk a high basal level of expression of hdcA, upregulation in the presence of free histidine and salt, and repression after thermization. HdcA activity persisted in cell extracts, indicating that histamine might accumulate after cell lysis in cheese.
本研究评估了与奶酪制作相关的参数对嗜热链球菌产生组胺的影响。具有组氨酸脱羧酶(hdcA)基因的菌株占筛选出的乳制品分离株的 6%。产组胺能力最强的嗜热链球菌 PRI60 在脱脂乳中 hdcA 的基础表达水平较高,在游离组氨酸和盐的存在下上调,热杀菌后下调。hdcA 活性在细胞提取物中持续存在,表明在奶酪中细胞裂解后组胺可能会积累。