Schiraldi C, Valli V, Molinaro A, Cartenì M, De Rosa M
Department of Experimental Medicine, Section of Biotechnology and Molecular Biology, Second University of Naples, via De Crecchio no. 7, 80138 Naples, Italy.
J Ind Microbiol Biotechnol. 2006 May;33(5):384-90. doi: 10.1007/s10295-005-0068-x. Epub 2006 Feb 7.
The physiology of Lactobacillus delbrueckii ssp. bulgaricus and Lactobacillus casei, extensively used in the dairy industry, was studied in order to evaluate key parameters in the synthesis of exopolysaccharides and to improve their production through novel fermentation processes. Selected strains were studied in shake flasks and in fermentor experiments using glucose and lactose as main carbon sources and bacto casitone as the only complex component, in a temperature range between 35 and 42 degrees C. The production of exopolysaccharides was monitored and correlated to the growth conditions using both a colorimetric assay and chromatographic methods. Fermentor experiments in batch mode yielded 100 mg l(-1) of EPS from L. bulgaricus and 350 mg l(-1) from L. casei. Moreover, the use of a microfiltration (MF) bioreactor resulted in exopolysaccharides (EPS) concentrations threefold and sixfold those of batch experiments, respectively. The monosaccharidic composition of the two analyzed polymers differed from those previously reported. The optimization of the production of EPSs using the MF fermentation strategy could permit the use of these molecules produced by generally recognised as safe (GRAS) microorganisms in the place of other polysaccharides in the food industry.
德氏乳杆菌保加利亚亚种和干酪乳杆菌在乳制品工业中广泛应用，对其生理学特性进行了研究，以评估胞外多糖合成中的关键参数，并通过新型发酵工艺提高其产量。选用的菌株在摇瓶和发酵罐实验中进行研究，以葡萄糖和乳糖作为主要碳源，以胰蛋白胨作为唯一的复合成分，温度范围在35至42摄氏度之间。使用比色法和色谱法监测胞外多糖的产生，并将其与生长条件相关联。分批模式的发酵罐实验中，德氏乳杆菌保加利亚亚种产生了100 mg l(-1)的胞外多糖，干酪乳杆菌产生了350 mg l(-1)。此外，使用微滤（MF）生物反应器分别使胞外多糖（EPS）浓度达到分批实验的三倍和六倍。两种分析聚合物的单糖组成与先前报道的不同。使用MF发酵策略优化胞外多糖的生产，可以允许在食品工业中使用这些由普遍认为安全（GRAS）的微生物产生的分子来替代其他多糖。
