Institute of Food Technology and Bioprocess Engineering, Technische Universität Dresden, 01069 Dresden, Germany.
J Biosci Bioeng. 2012 Feb;113(2):185-91. doi: 10.1016/j.jbiosc.2011.10.012. Epub 2011 Nov 9.
Some Lactobacillus delbrueckii ssp. bulgaricus strains are able to synthesize exopolysaccharides (EPS) and are therefore highly important for the dairy industry as starter cultures. The aim of this study was to investigate the nutritional requirements for growth and EPS production of Lactobacillus delbrueckii ssp. bulgaricus DSM 20081. A medium was developed from a semi-defined medium (SDM) in which glucose was replaced by lactose and different combinations of supplements (nucleobases, vitamins, salts, sodium formate and orotic acid) were added. Constant pH batch fermentation with the modified medium resulted in an EPS yield of approximately 210 mg glucose equivalents per liter medium. This was a 10-fold increase over flask cultivation of this strain in SDM. Although not affecting cell growth, the mixture of salts enhanced the EPS synthesis. Whereas EPS production was approximately 12 mg/g dry biomass without salt supplementation, a significantly higher yield (approximately 20 mg/g dry biomass) was observed after adding the salt mixture. In continuous fermentation, a maximal EPS concentration was obtained at a dilution rate of 0.31/h (80 mg EPS/L), which corresponded to a specific EPS production of 49 mg/g dry biomass.
一些德氏乳杆菌保加利亚亚种菌株能够合成胞外多糖（EPS），因此作为发酵剂对乳制品工业非常重要。本研究旨在研究德氏乳杆菌保加利亚亚种 DSM 20081 的生长和 EPS 生产的营养需求。从半确定培养基（SDM）中开发出一种培养基，其中葡萄糖被乳糖替代，并添加了不同组合的补充剂（核碱基、维生素、盐、甲酸钠和乳清酸）。用改良培养基进行恒 pH 分批发酵，导致 EPS 产量约为每升培养基 210 毫克葡萄糖当量。这比在 SDM 中培养该菌株的摇瓶培养增加了 10 倍。虽然盐混合物不影响细胞生长，但它增强了 EPS 的合成。在没有盐补充的情况下，EPS 产量约为 12 毫克/克干生物量，而添加盐混合物后，产量明显更高（约 20 毫克/克干生物量）。在连续发酵中，在稀释率为 0.31/h（80 毫克 EPS/L）时获得了最大的 EPS 浓度，这对应于 49 毫克/克干生物量的特定 EPS 生产。
