S-腺苷甲硫氨酸(S-adenosylmethionine,SAM),可作为营养补充剂用于改善人体健康,对人体新陈代谢至关重要。在解淀粉芽胞杆菌从头合成SAM的过程中,脂肽类表面活性剂常导致能量损失、发酵起泡等问题,不利于SAM的积累。通过研究敲除解淀粉芽孢杆菌脂肽类表面活性剂合成基因ituD和srfAC,探究该类基因对SAM从头合成的影响。实验结果显示:单敲除ituD基因并未对菌体生长和SAM合成产生显著的影响,单敲除srfAC基因促进SAM产量提高了23%,对菌体生长影响不显著;叠加敲除ituD和srfAC后,SAM产量提高32%,且对菌体生长没有显著性影响。研究首次证实敲除脂肽类表面活性剂基因可显著提高SAM产量,研究结果为SAM的代谢工程育种提供了新策略。
S-Adenosylmethionine (SAM) is highly important for human metabolism, and it can be used as a nutritional supplement to improve human health. During the de novo synthesis of SAM by Bacillus amyloliquefaciens, lipopeptide surfactants usually lead to energy loss and fermentation foaming, which may hinder the accumulation of SAM. In this study, the lipopeptide surfactants synthesis genes of ituD and srfAC were deleted and effects of these genes on SAM synthesis were investigated. The fermentation results showed that deletion of ituD had no significant effect on cell growth and SAM synthesis. On the other hand, deletion of srfAC promoted the SAM titer by 23%, and no significant effect was found on the cell growth. After double mutation of ituD and srfAC, the SAM titer was increased by 32%, and the cell growth was not affected significantly. This study confirms that blocked lipopeptide surfactants synthesis can significantly enhance the SAM production, which provides a new strategy for metabolic engineering breeding of SAM.
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