CNIEL, Paris Cedex 09, France; INRA, UMR 782 Génie et Microbiologie des Procédés Alimentaires (GMPA), Thiverval-Grignon, France; AgroParisTech, UMR 782 Génie et Microbiologie des Procédés Alimentaires (GMPA), Thiverval-Grignon, France.
J Appl Microbiol. 2014 Sep;117(3):729-40. doi: 10.1111/jam.12577. Epub 2014 Jul 8.
To investigate the effects of fermentation parameters on the cell growth and on the resistance to each step of the freeze-drying process of Lactococcus lactis subsp. lactis TOMSC161, a natural cheese isolate, using a response surface methodology.
Cells were cultivated at different temperatures (22, 30 and 38°C) and pH (5·6, 6·2 and 6·8) and were harvested at different growth phases (0, 3 and 6 h of stationary phase). Cultivability and acidification activity losses of Lc. lactis were quantified after freezing, drying, 1 and 3 months of storage at 4 and 25°C. Lactococcus lactis was not damaged by freezing but was sensitive to drying and to ambient temperature storage. Moreover, the fermentation temperature and the harvesting time influenced the drying resistance of Lc. lactis.
Lactococcus lactis cells grown in a whey-based medium at 32°C, pH 6·2 and harvested at late stationary phase exhibited both an optimal growth and the highest resistance to freeze-drying and storage.
A better insight on the individual and interaction effects of fermentation parameters made it possible the freeze-drying and storage preservation of a sensitive strain of technological interest. Evidence on the particularly damaging effect of the drying step and the high-temperature storage is presented.
采用响应面法研究发酵参数对干酪乳杆菌亚种汤姆森 TOMSC161 细胞生长和对冷冻干燥过程中各步骤抗性的影响。
在不同温度（22、30 和 38°C）和 pH 值（5.6、6.2 和 6.8）下培养细胞，并在不同的生长阶段（静止期的 0、3 和 6 h）收获细胞。在冷冻、干燥、在 4 和 25°C 下储存 1 和 3 个月后，定量测定干酪乳杆菌的可培养性和酸化活性损失。干酪乳杆菌不会因冷冻而受损，但对干燥和环境温度储存敏感。此外，发酵温度和收获时间影响干酪乳杆菌的干燥抗性。
在乳清基培养基中于 32°C、pH 值 6.2 下生长并在后期静止期收获的干酪乳杆菌细胞表现出最佳生长和对冷冻干燥及储存的最高抗性。
对发酵参数的单独和相互作用效应的更深入了解使得对敏感的具有技术兴趣的菌株的冷冻干燥和储存保存成为可能。本文提供了干燥步骤和高温储存具有特别破坏性影响的证据。
