Mahara Fenny Amilia, Nuraida Lilis, Lioe Hanifah Nuryani
Department of Food Science and Technology, Faculty of Agricultural Engineering and Technology and.
Southeast Asian Food and Agricultural Science and Technology (SEAFAST) Center, IPB University (Bogor Agricultural University), Bogor 16680, Indonesia.
Prev Nutr Food Sci. 2021 Jun 30;26(2):230-240. doi: 10.3746/pnf.2021.26.2.230.
Folates are essential micronutrients, and folate deficiency still occurs in many countries. Lactic acid bacteria (LAB) are known to be able to synthesize folates during fermentation, but the folate production is strain-dependent and influenced by the fermentation medium, presence of a folate precursor, and fermentation time. This study aimed to screen extracellular folate-producing LAB from local food sources and evaluate the factors influencing their folate biosynthesis during milk fermentation. The selection of folate-producing LAB was based on their ability to grow in folate-free medium (FACM), with folate concentrations quantified by microbiological assay. Growth of the 18 LAB in FACM varied between isolates, with only 8 isolates growing well and able to synthesize extracellular folate at relatively high concentrations (up to 24.27 ng/mL). The isolates with highest extracellular folate levels, JK13 from kefir granules, 4C261 from salted mustard, and R23 from breast milk, were applied to milk fermentation. The last two isolates were probiotic candidates. The three isolates consumed folate when it was present in the milk, and its consumption was in line with their growth. The availability of folate precursors affected the amount of folate consumed, but did not lead to increased folate concentrations in the medium after 72 h fermentation. The results of this study indicate that these isolates cannot be utilized for producing folate in folate-containing milk, as it shows feedback inhibition on folate biosynthesis.
叶酸是必需的微量营养素，许多国家仍存在叶酸缺乏的情况。已知乳酸菌（LAB）在发酵过程中能够合成叶酸，但叶酸的产量因菌株而异，并受发酵培养基、叶酸前体的存在以及发酵时间的影响。本研究旨在从当地食物来源中筛选产细胞外叶酸的乳酸菌，并评估牛奶发酵过程中影响其叶酸生物合成的因素。产叶酸乳酸菌的筛选基于它们在无叶酸培养基（FACM）中生长的能力，通过微生物测定法定量叶酸浓度。18株乳酸菌在FACM中的生长情况因菌株而异，只有8株生长良好，能够合成相对高浓度（高达24.27 ng/mL）的细胞外叶酸。将细胞外叶酸水平最高的分离株，来自开菲尔粒的JK13、来自腌芥菜的4C261和来自母乳的R23，应用于牛奶发酵。后两个分离株是益生菌候选菌株。这三株分离株在牛奶中存在叶酸时会消耗叶酸，其消耗量与它们的生长情况一致。叶酸前体的可用性影响叶酸的消耗量，但在72小时发酵后不会导致培养基中叶酸浓度增加。本研究结果表明，这些分离株不能用于在含叶酸的牛奶中生产叶酸，因为它对叶酸生物合成表现出反馈抑制作用。
