Dairy Research Institute (IPLA-CSIC), Paseo Rio Linares s/n, 33300, Villaviciosa, Spain.
Sci Rep. 2018 Mar 5;8(1):3989. doi: 10.1038/s41598-018-22309-6.
This work reports a Lactobacillus rossiae strain (L. rossiae D87) isolated from sourdough that synthesizes putrescine - a biogenic amine that raises food safety and spoilage concerns - from arginine via the ornithine decarboxylase (ODC) pathway. The odc and potE genes were identified and sequenced. These genes respectively encode ornithine decarboxylase (Odc), which participates in the decarboxylation of ornithine to putrescine, and the ornithine/putrescine exchanger (PotE), which exchanges ornithine for putrescine. Transcriptional analysis showed that odc and potE form an operon that is regulated transcriptionally by ornithine in a dose-dependent manner. To explore the possible role of the ODC pathway as an acid stress resistance mechanism for this bacterium, the effect of acidic pHs on its transcriptional regulation and on putrescine biosynthesis was analysed. Acidic pHs induced the transcription of the odc-potE genes and the production of putrescine over that seen at neutral pH. Further, putrescine production via the ODC system improved the survival of L. rossiae D87 by counteracting the acidification of the cytoplasm when the cells were subjected to acidic conditions. These results suggest the ODC pathway of L. rossiae D87 provides a biochemical defence mechanism against acidic environments.
本研究报道了一株来自于酸面团的罗斯氏乳杆菌（Lactobacillus rossiae D87），该菌通过精氨酸的鸟氨酸脱羧酶（ODC）途径合成腐胺——一种引起食品安全和腐败问题的生物胺。鉴定并测序了 odc 和 potE 基因。这些基因分别编码参与鸟氨酸脱羧生成腐胺的鸟氨酸脱羧酶（Odc）和鸟氨酸/腐胺交换器（PotE）。转录分析表明，odc 和 potE 形成一个操纵子，该操纵子受鸟氨酸的转录调控，呈剂量依赖性。为了探究 ODC 途径作为该菌耐酸应激机制的可能作用，分析了酸性 pH 值对其转录调控和腐胺生物合成的影响。酸性 pH 值诱导 odc-potE 基因的转录，并使腐胺的产生高于中性 pH 值。此外，通过 ODC 系统产生腐胺可通过中和细胞在酸性条件下的细胞质酸化来提高 L. rossiae D87 的存活率。这些结果表明，L. rossiae D87 的 ODC 途径为其提供了一种针对酸性环境的生化防御机制。
