Key Laboratory of Functional Dairy, Ministry of Education, College of Food Science and Nutritional Engineering, China Agricultural University, Haidian, Beijing, 100083, China.
Curr Microbiol. 2011 Feb;62(2):612-7. doi: 10.1007/s00284-010-9751-x. Epub 2010 Sep 11.
The acid adaption is commonly used as a strategy to enhance the acid tolerance of bifidobacteria. However, the acid tolerance response (ATR) mechanism elicited by this method is unclear. Real-time relative-quantitative PCR was applied to analyze the changes in the expressions of ffh, uvrA, groES, and dnaK involved in the ATR after acid-adaptation in Bifidobacterium longum BBMN68 in different growth phases. BBMN68 was cultured at a constant neutral pH during the whole growth phase. Without acid-adaptation, the survival ratios at the lethal pH 3.0 were 0.25% and 17% in the exponential and stationary phases, respectively. The genes ffh, uvrA, groES, and dnaK were significantly higher in the stationary phase than in the exponential phase. The results indicated that although there was no acid stress, the acid tolerance of cells was elevated from the exponential phase into stationary phase. After acid-adaptation at pH 5.0 for 120 min, the survival ratios of BBMN68 in the exponential and stationary phases were increased to 2.5 and 31%, respectively. In the exponential phase, ffh, uvrA groES, and dnaK were significantly decreased after acid-adaptation. In the stationary phase, after acid-adaptation for 15, 60, and 120 min, the genes uvrA, groES, and dnaK were significantly decreased, whereas, ffh was significantly up-regulated at 15 min, and then suppressed at 60 and 120 min after acid-adaptation. The results represented that the ATR in B. longum was different from other bacteria, and ffh may be the transient acid gene.
酸适应通常被用作增强双歧杆菌耐酸性的策略。然而，这种方法引起的耐酸应答（ATR）机制尚不清楚。应用实时相对定量 PCR 分析长双歧杆菌 BBMN68 在不同生长阶段经酸适应后参与 ATR 的 ffh、uvrA、groES 和 dnaK 基因的表达变化。BBMN68 在整个生长阶段均在恒定中性 pH 下培养。未经酸适应时，在致死 pH 3.0 下指数期和静止期的存活率分别为 0.25%和 17%。静止期的 ffh、uvrA、groES 和 dnaK 基因明显高于指数期。结果表明，尽管没有酸胁迫，但细胞的耐酸性从指数期升高到静止期。经 pH 5.0 酸适应 120 min 后，BBMN68 在指数期和静止期的存活率分别提高到 2.5%和 31%。在指数期，经酸适应后 ffh、uvrA、groES 和 dnaK 基因明显降低。在静止期，经酸适应 15、60 和 120 min 后，uvrA、groES 和 dnaK 基因明显降低，而 ffh 在酸适应 15 min 时明显上调，然后在 60 和 120 min 时受到抑制。结果表明，长双歧杆菌的 ATR 与其他细菌不同，ffh 可能是瞬时酸基因。
