Ohba Tetsuro, Uemura Kunihiko, Nabetani Hiroshi
a Global Food Safety Institutes, Nissin Foods Holdings , Tokyo , Japan.
b Division of Food Processing and Distribution Research , Food Research Institute, National Agriculture and Food Research Organization , Tsukuba , Japan.
Biosci Biotechnol Biochem. 2017 Apr;81(4):724-734. doi: 10.1080/09168451.2016.1277511. Epub 2017 Jan 17.
Metabolome analysis and physicochemical analyses were executed with cell extracts of a Lactococcus lactis subspecies cremoris strain treated by moderate pulsed electric field (PEF) to elucidate the mechanism of enhanced production of exopolysaccharide (EPS) by the treatment. Metabolome analysis by capillary electrophoresis time of flight mass spectrometry annotated 224 metabolites from the cytoplasmic extract of the strain, which, however, showed no significant changes in metabolites related to the EPS production. Electron microscopic observation and chemical analysis of undecaprenoids as carrier of EPS biosynthetic intermediates suggested that PEF treatment dissociated immature EPSs from the intermediates due to the focal electro-condensation of hydrogen ions at the cell surface. Thus, liberated undecaprenyl phosphates were recycled efficiently, which resulted in mass increase of EPS with smaller molecular weight. The study suggested the feasibility of moderate PEF treatment as a food processing technique and revealed the mechanism of enhanced production of EPS by the treatment.
采用适度脉冲电场（PEF）处理乳酸乳球菌乳脂亚种菌株，对其细胞提取物进行代谢组分析和理化分析，以阐明该处理增强胞外多糖（EPS）产生的机制。通过毛细管电泳飞行时间质谱进行的代谢组分析注释了该菌株细胞质提取物中的224种代谢物，然而，与EPS产生相关的代谢物没有显著变化。对作为EPS生物合成中间体载体的十一异戊二烯类进行电子显微镜观察和化学分析表明，PEF处理由于氢离子在细胞表面的局部电凝聚作用，使未成熟的EPS与中间体解离。因此，释放的十一异戊烯磷酸被有效循环利用，导致EPS分子量减小但质量增加。该研究表明适度PEF处理作为一种食品加工技术的可行性，并揭示了该处理增强EPS产生的机制。
