State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, No. 1 Shizishan Street, Hongshan District, Wuhan, 430070, Hubei, China.
State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, College of Life Sciences, Hubei University, Wuhan, 430062, China.
Metabolomics. 2019 Feb 20;15(3):25. doi: 10.1007/s11306-019-1492-7.
Acetoin serves as a high value-added platform with a broad range of applications, and can be effectively produced by Bacillus licheniformis. However, its toxicity to the producing strain hinders the higher acetoin production, and current knowledge about the acetoin resistance mechanisms of B. licheniformis is quite limited.
To comprehensively investigate the metabolic changes in B. licheniformis under acetoin stress.
We used gas chromatography-mass spectrometry based untargeted metabolomics approach to measure the metabolic profiles of B. licheniformis under 20, 40 and 80 g/L acetoin stress. Transcriptional analysis was conducted to verify the metabolomics results.
A total of 119 metabolites were identified in our experiment. The metabolic responses of B. licheniformis to acetoin stress were as follows: (i) pentose phosphate pathway and tricarboxylic acid (TCA) cycle were negatively affected by acetoin stress. In turn, glyoxylate cycle was activated to supply malic acid. (ii) Acetoin stress induced the accumulation of serine, valine, leucine and protective osmolytes (glycine and proline). (iii) Acetoin stress induced a higher saturated fatty acid ratio, which indicated a lower fluidity of cell membrane that could inhibit the entry of acetoin into cytoplasm. (iv) Synthesis of phosphatidylserine was enhanced, and phosphatidylethanolamine content was probably increased under acetoin stress.
This study revealed the metabolic perturbations of B. licheniformis to acetoin stress. In response to acetoin stress, glyoxylate cycle was activated, protective osmolytes were accumulated, saturated fatty acid ratio was elevated and synthesis of phosphatidylserine was enhanced in B. licheniformis.
乙酰丙酮是一种具有广泛应用价值的高附加值平台化合物，可以通过地衣芽孢杆菌有效地生产。然而，其对生产菌株的毒性阻碍了更高产乙酰丙酮，目前对地衣芽孢杆菌对乙酰丙酮抗性机制的了解相当有限。
全面研究地衣芽孢杆菌在乙酰丙酮胁迫下的代谢变化。
我们采用气相色谱-质谱联用的非靶向代谢组学方法测量了地衣芽孢杆菌在 20、40 和 80 g/L 乙酰丙酮胁迫下的代谢谱。进行转录分析以验证代谢组学结果。
本实验共鉴定出 119 种代谢物。地衣芽孢杆菌对乙酰丙酮胁迫的代谢反应如下：（i）戊糖磷酸途径和三羧酸（TCA）循环受到乙酰丙酮胁迫的负面影响。相反，乙醛酸循环被激活以提供苹果酸。（ii）乙酰丙酮胁迫诱导丝氨酸、缬氨酸、亮氨酸和保护性渗透物（甘氨酸和脯氨酸）的积累。（iii）乙酰丙酮胁迫诱导更高的饱和脂肪酸比例，这表明细胞膜的流动性降低，可抑制乙酰丙酮进入细胞质。（iv）在乙酰丙酮胁迫下，合成磷脂酰丝氨酸增强，可能增加磷脂酰乙醇胺的含量。
本研究揭示了地衣芽孢杆菌对乙酰丙酮胁迫的代谢变化。地衣芽孢杆菌响应乙酰丙酮胁迫，激活乙醛酸循环，积累保护性渗透物，增加饱和脂肪酸比例，增强磷脂酰丝氨酸的合成。
