School of Biology and Basic Medical Sciences, Soochow University, 199# Ren'ai Road, Suzhou, 215123, People's Republic of China.
Appl Microbiol Biotechnol. 2018 Oct;102(20):8921-8930. doi: 10.1007/s00253-018-9292-y. Epub 2018 Aug 17.
The effect of sodium chloride (NaCl) on pullulan production by batch culture of Aureobasidium pullulans CCTCC M 2012259 was investigated. NaCl at 3 g/L improved the pullulan titer by 26.7% but reduced the molecular weight of pullulan to only 46.8% of that obtained in the control without NaCl. In order to elucidate the physiological mechanism underlying the effect of NaCl on pullulan production, assays of key enzyme activity, gene expression, energy metabolism, and intracellular uridine diphosphate glucose (UDP-glucose) content were performed. Results indicated that NaCl increased the activities of α-phosphoglucose mutase and glucosyltransferase involved in pullulan biosynthesis, increased the activities of α-amylase being responsible for pullulan degradation, upregulated the transcriptional levels of pgm1, fks, and amy2 genes, enhanced the driving force for ATP supply, and helped to maintain intracellular UDP-glucose at a high level in A. pullulans CCTCC M 2012259. All these results illuminate the reason by which NaCl increases pullulan titer but reduces the molecular weight of pullulan.
研究了氯化钠（NaCl）对出芽短梗霉 CCTCC M 2012259 分批培养生产普鲁兰的影响。3 g/L 的 NaCl 使普鲁兰的产量提高了 26.7%，但将普鲁兰的分子量降低到对照（无 NaCl）的 46.8%。为了阐明 NaCl 对普鲁兰生产影响的生理机制，进行了关键酶活性、基因表达、能量代谢和细胞内尿苷二磷酸葡萄糖（UDP-葡萄糖）含量的测定。结果表明，NaCl 增加了参与普鲁兰生物合成的α-磷酸葡萄糖变位酶和葡糖基转移酶的活性，增加了负责普鲁兰降解的α-淀粉酶的活性，上调了 pgm1、fks 和 amy2 基因的转录水平，增强了 ATP 供应的驱动力，并有助于维持出芽短梗霉 CCTCC M 2012259 细胞内 UDP-葡萄糖的高水平。这些结果阐明了 NaCl 提高普鲁兰产量但降低普鲁兰分子量的原因。
