The unsaturated fatty acid of the cell membrane and the accumulation of intracellular glutamic acid as key determinants of freeze-drying tolerance in Bifidobacterium bifidum.
- 2026-03
- Food research international (Ottawa, Ont.) 228
- Shuyu Guo
- Wenrui Zhou
- Bingyong Mao
- Xin Tang
- Qiuxiang Zhang
- Jianxin Zhao
- Wei Chen
- Shumao Cui
- PubMed: 41703885
- DOI: 10.1016/j.foodres.2026.118444
The sensitivity of Bifidobacterium bifidum (B. bifidum) to freeze-drying limits its commercialization. To unravel the mechanistic basis of this sensitivity, this study compared the freeze-drying-resistant Bifidobacterium longum FJND2M2 with the susceptible B. bifidum CCFM16. For this purpose, a comparative analysis of the cell structure and composition characteristics of the two strains was conducted. The results showed that there were no significant differences in cell size, exopolysaccharides content and cell wall thickness. In contrast, FJND2M2 exhibited two key advantageous traits: a higher content of unsaturated fatty acids in the cell membrane and significantly elevated intracellular glutamic acid accumulation. Based on these findings, targeted structural regulation was performed on B. bifidum CCFM16. The addition of Tween 80 or sodium oleate increased membrane unsaturation and freeze-drying survival rate. Additionally, exogenous glutamic acid supplementation enhanced the freeze-drying survival rate of CCFM16 (up to 48.83 ± 2.04%), which was mediated by the upregulation of the gluABCD gene cluster that promotes intracellular glutamic acid accumulation. Proteomic analysis further revealed that the upregulation of ion transport and DNA repair pathways was associated with the enhanced freeze-drying tolerance. This study has achieved a key shift from passive mechanism clarification to active target engineering, providing a reasonable framework for enhancing the industrial robustness of sensitive probiotics.
Research Insights
| Supplement | Health Outcome | Effect Type | Effect Size |
|---|---|---|---|
| Bifidobacterium bifidum | Improved Survival | Beneficial | Moderate |