Kimmel S A, Roberts R F
Department of Food Science, The Pennsylvania State University, University Park 16802, USA.
Int J Food Microbiol. 1998 Mar 3;40(1-2):87-92. doi: 10.1016/s0168-1605(98)00023-3.
Complex media are commonly used in studies examining exopolysaccharide production by Lactobacillus delbrueckii ssp. bulgaricus. However, quantification of exopolysaccharide in complex medium can be complicated by interference due to carbohydrate polymers contained in media components. This study was undertaken to identify components of MRS, a common medium for cultivation of L. delbrueckii ssp. bulgaricus, that interfere with exopolysaccharide quantification, to develop a medium for production of exopolysaccharide that provides for growth of L. delbrueckii ssp. bulgaricus strain RR similar to MRS, and to demonstrate exopolysaccharide production by L. delbrueckii ssp. bulgaricus RR grown in the newly developed medium. Phenol-sulfuric acid determinations were conducted on uninoculated MRS broth with and without yeast extract, beef extract and proteose peptone #3. These three ingredients accounted for 94% of the total background exopolysaccharide-equivalent in MRS broth. Based on these results, a semi-defined medium (SDM) providing minimal interference was developed using yeast nitrogen base and Bacto casitone. Growth of L. delbrueckii ssp. bulgaricus RR at 42 degrees C in semi-defined medium and MRS was evaluated, and generation times did not differ significantly (0.94 h in MRS and 0.85 h in SDM). Exopolysaccharide production by L. delbrueckii ssp. bulgaricus RR during growth in semi-defined medium was evaluated at 30 and 40 degrees C. The rate of exopolysaccharide production was lower at 30 degrees C (8.04 (mg/l-h) than at 40 degrees C (11.95 (mg/l-h), but the maximal concentration of exopolysaccharide produced was similar at both temperatures.
复杂培养基常用于研究德氏乳杆菌保加利亚亚种的胞外多糖产生情况。然而，复杂培养基中胞外多糖的定量可能会因培养基成分中含有的碳水化合物聚合物产生干扰而变得复杂。本研究旨在确定用于培养德氏乳杆菌保加利亚亚种的常用培养基MRS中干扰胞外多糖定量的成分，开发一种能支持德氏乳杆菌保加利亚亚种RR菌株生长且类似于MRS的胞外多糖生产培养基，并证明在新开发的培养基中生长的德氏乳杆菌保加利亚亚种RR能产生胞外多糖。对未接种的含和不含酵母提取物、牛肉提取物和蛋白胨#3的MRS肉汤进行了苯酚-硫酸法测定。这三种成分占MRS肉汤中总背景胞外多糖当量的94%。基于这些结果，使用酵母氮碱和酪蛋白胰酶水解物开发了一种干扰最小的半限定培养基（SDM）。评估了德氏乳杆菌保加利亚亚种RR在42℃下在半限定培养基和MRS中的生长情况，代时无显著差异（MRS中为0.94小时，SDM中为0.85小时）。在30℃和40℃下评估了德氏乳杆菌保加利亚亚种RR在半限定培养基中生长期间的胞外多糖产生情况。30℃时胞外多糖产生速率（8.04（mg/l·h）低于40℃时（11.95（mg/l·h），但两个温度下产生的胞外多糖最大浓度相似。
