Gaudreau H, Renard N, Champagne C P, Van Horn D
Food and Research Development Centre, Agriculture and Agri-Food Canada, St Hyancynth, QC, Canada.
Can J Microbiol. 2002 Jul;48(7):626-34. doi: 10.1139/w02-052.
The effectiveness of yeast extracts (YE) and potato extracts (PE) to promote growth of seven lactic cultures was evaluated by automated spectrophotometry (AS). Two aspects of the growth curve were analysed: (1) maximum biomass obtained (using ODmax) and (2) highest specific growth rate mu(max)) Eleven lots from the same PE-manufacturing process were examined for lot-to-lot variability. The ODmax values of three of the seven strains were significantly affected by lot source, but mu(max) was not significantly affected. The growth of bacteria was systematically lower in base medium containing 100% PE than in base medium containing 100% YE for both ODmax or mu(max) data, which could be related to the lower content in nitrogen-based compounds in PE. In AS assays, highest OD values for Lactobacillus casei EQ28, Lactobacillus rhamnosus R-011, Lactobacillus plantarum EQ12, and Streptococcus thermophilus R-083 were obtained with a mixture of PE and YE. Fermentations (2 L) were also carried out to determine the accuracy of AS to predict biomass levels obtained under fermentation trials. In these fermentations, replacement of 50% YE with PE was shown to enable good growth of S. thermophilus. With L. rhamnosus R-011, a high correlation (R2 = 0.95) was found between ODmax data obtained in the AS assays and that of the 2-L bioreactor when the same growth medium was used for both series of fermentations. However, AS was not as efficient when industrial media were used for the bioreactor assays. The relationship was still good for ODmax between AS data and that of the bioreactor data with L. rhamnosus R-011 in industrial LBS medium (R2 = 0.87), but was very poor with the S. thermophilus R-083 on Rosell #43 industrial medium (R2 = 0.33). Since PE cost 40% less than YE, there are strong economic advantages in considering such a partial replacement of YE by PE.
通过自动分光光度法（AS）评估了酵母提取物（YE）和马铃薯提取物（PE）对7种乳酸菌生长的促进效果。分析了生长曲线的两个方面：（1）获得的最大生物量（使用ODmax）和（2）最高比生长速率μ（max）。对来自同一PE生产过程的11批产品进行了批次间变异性检查。7种菌株中的3种的ODmax值受批次来源的显著影响，但μ（max）不受显著影响。对于ODmax或μ（max）数据，在含有100%PE的基础培养基中细菌的生长系统地低于含有100%YE的基础培养基，这可能与PE中氮基化合物含量较低有关。在AS测定中，干酪乳杆菌EQ28、鼠李糖乳杆菌R - 011、植物乳杆菌EQ12和嗜热链球菌R - 083的最高OD值是在PE和YE的混合物中获得的。还进行了2L发酵以确定AS预测发酵试验中获得的生物量水平的准确性。在这些发酵中，用PE替代50%的YE被证明能使嗜热链球菌良好生长。对于鼠李糖乳杆菌R - 011，当两个系列的发酵使用相同的生长培养基时，在AS测定中获得的ODmax数据与2L生物反应器的ODmax数据之间发现高度相关性（R2 = 0.95）。然而，当工业培养基用于生物反应器测定时，AS效率不高。在工业LBS培养基中，鼠李糖乳杆菌R - 011的AS数据与生物反应器数据之间的ODmax关系仍然良好（R2 = 0.87），但在罗塞尔#43工业培养基上嗜热链球菌R - 083的关系非常差（R2 = 0.33）。由于PE的成本比YE低40%，考虑用PE部分替代YE具有很强的经济优势。
