Abstract

The development of new starter cultures is a crucial task for the food industry to meet technological requirements and traditional products are important reservoirs for new starter cultures. In this respect, this study aimed to isolate, identify, and determine the technological characteristics of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains originated from traditional yogurt samples. Genotypic discrimination of 200 isolates revealed the presence of distinct 19 S. thermophilus and 11 Lb. delbrueckii subsp. bulgaricus strains as potential starter cultures. Strain-specific properties determined the acidification capacity of the yogurt starter cultures and a higher acidification capacity was observed for S. thermophilus strains compared to Lb. delbrueckii subsp. bulgaricus strains. Proteolytic activity was found between 0.012–0.172 and 0.078–0.406 for S. thermophilus and Lb. delbrueckii subsp. bulgaricus strains, respectively. 4 of S. thermophilus and 3 of Lb. delbrueckii subsp. bulgaricus strains were found resistant to all tested bacteriophages. The antibiotic susceptibility tests of the isolates revealed that a very low antibiotic resistance was observed for the yogurt starter cultures. Finally, the growth kinetics of selected strains were determined and the maximum specific growth rate of selected S. thermophilus and Lb. delbrueckii subsp. bulgaricus was calculated as 0.527 h⁻¹ and 0.589 h⁻¹, respectively.

摘要

新型发酵剂的开发是食品工业满足技术要求的关键任务，传统产品是新型发酵剂的重要储存库。在这方面，本研究旨在分离、鉴定和确定德氏乳杆菌亚种的技术特征。bulgaricus和Streptococcus thermophilus菌株源自传统酸奶样品。200 个分离株的基因型鉴别显示存在不同的 19嗜热链球菌和 11 Lb。德氏亚种 保加利亚菌株作为潜在的起始培养物。菌株特异性特性决定了酸奶发酵剂的酸化能力，与Lb相比，嗜热链球菌菌株的酸化能力更高。德氏亚种 保加利亚菌株。嗜热链球菌和Lb的蛋白水解活性在 0.012–0.172 和 0.078–0.406 之间。德氏亚种 保加利亚菌株，分别。4 个嗜热链球菌和 3 个Lb。德氏亚种 保加利亚发现菌株对所有测试的噬菌体具有抗性。分离株的抗生素敏感性试验表明，酸奶发酵剂的抗生素耐药性非常低。最后，确定了所选菌株的生长动力学以及所选嗜热链球菌和Lb的最大比生长速率。德氏亚种 bulgaricus分别计算为 0.527 h ^-1和 0.589 h ^-1。