School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, Australia.
Mol Biotechnol. 2013 Jun;54(2):371-8. doi: 10.1007/s12033-012-9576-x.
Bacillus subtilis natto is the key microorganism for the industrial production of menaquinone-7. The fermentation of this bacterium in static culture is associated with biofilm formation. The objective of this study was to determine the effect of biofilm formation on menaquinone-7 production to develop a suitable bio-reactor for the production of menaquinone-7. In the static culture, menaquinone-7 biosynthesis showed a linear correlation with biofilm formation (R (2) = 0.67) and cell density (R (2) = 0.7). The amount of biofilm, cell density and menaquinone-7 formation were a function of nutrient and processing conditions. Glycerol, soy peptone, and yeast extract mixture and 40 °C were found to be the optimum nutrients and temperature for accelerating both biofilm and menaquinone-7 biosynthesis in static culture. However, glucose, mixture of soy peptone and yeast extract and 45 °C were found to be the optima for cell density. As compared to the static culture, the biofilm formation was significantly inhibited when a shaken fermentation was used. However, shaking caused only a small decrease on menaquinone-7 production. These results demonstrate that the biofilm formation is not essential for menaquinone-7 biosynthesis. This study underlines the feasibility of using large scale stirred fermentation process for menaquinone-7 production.
纳豆芽孢杆菌是工业生产维生素 K2（menaquinone-7）的关键微生物。该细菌在静态培养中发酵时会形成生物膜。本研究旨在确定生物膜形成对menaquinone-7 生产的影响，以开发适合生产menaquinone-7 的生物反应器。在静态培养中，menaquinone-7 的生物合成与生物膜形成（R²=0.67）和细胞密度（R²=0.7）呈线性相关。生物膜量、细胞密度和menaquinone-7 的形成是营养物质和处理条件的函数。发现甘油、大豆蛋白胨和酵母提取物混合物以及 40°C 是加速静态培养中生物膜和menaquinone-7 生物合成的最佳营养物质和温度。然而，葡萄糖、大豆蛋白胨和酵母提取物混合物以及 45°C 是最佳细胞密度条件。与静态培养相比，使用摇瓶发酵时生物膜形成受到显著抑制。然而，摇瓶培养对menaquinone-7 生产的影响很小。这些结果表明，生物膜形成对于menaquinone-7 的生物合成不是必需的。本研究强调了使用大规模搅拌发酵工艺生产menaquinone-7 的可行性。
