产叶酸乳酸菌的筛选及生物学特性研究-微生物学专业论文.docxVIP

摘要 叶酸（Folic acid）是生物体中一种重要的维生素，作为碳架单位的载体参与的甲 基化反应，与体内 DNA、RNA 及蛋白质的合成密切相关，在机体内代谢过程中发挥 着非常重要的作用。缺乏叶酸将会导致一系列的疾病，如神经系统疾病、巨红细胞贫 血、肿瘤、心血管疾病等。 本研究对课题组保存的 36 株乳酸菌进行产叶酸的筛选，并对产叶酸菌株进行生 长温度、碳水化合物利用、耐酸性等试验及生物学特性研究。结果表明 36 株菌中有 10 株菌产叶酸，进一步复筛得到 3 株产叶酸量较高菌株 C-17、CH-2、C-25。经微生 物形态学和生理生化特性初步确定 C-17 为植物乳杆菌（Lactobacillus plantarum）， CH-2 为嗜酸乳杆菌（Lactobacillus acidophilus），C-25 为戊糖乳杆菌（Lactobacillus pentosus）。 利用分子生物学方法对 C-17、CH-2、C-25 进行 16S rDNA 的扩增与测序，并与 标准菌株做同源性分析，结果表明菌株 C-17 与 Lactobacillus plantarum NRIC 1829 的 同源性为 99%，菌株 CH-2 与 Lactobacillus acidophilus ATCC 4356 的同源性为 100%， 菌株 C-25 与 Lactobacillus pentosus NRIC 1837 的同源性为 100%。综合形态学、生理 生化、分子生物学鉴定结果，可判定 C-17 为植物乳杆菌，CH-2 为嗜酸乳杆菌，C-25 为戊糖乳杆菌。 通过对以上三株乳酸菌的生长动力学研究，其最适生长温度均为 37℃，起始 pH 值为 6.2，葡萄糖为最佳碳源，蛋白胨、胰蛋白胨、酪蛋白胨均可作为氮源。菌株 C-17 和 CH-2 培养 16h 后菌体密度达到最大值，菌株 C-25 为 18h。 关键词： 叶酸；乳酸菌；筛选；生物学特性 Screening of Lactic Acid Bacteria Producing Folic Acid and Study on Its Biological Characteristics Author: Zhao Hongfei Supervisors: Professor Dr. Zhang Bolin Major: Microbiology ABSTRACT Folic acid is a vitamin that accepts one-carbon units from donor molecules and is involved in many metabolic pathways, such as methyl group biogenesis and synthesis of nucleotides, vitamins, and some amino acids. Folic acid deficiency is often associated with increased cancer, neural tube defects, anaemia, atherosclerosis and heart attack. 36 lactic acid bacterias were studied in this subject，screening the one can product Folic acid. Studied on temperature, carbohydrate utilization test and acid-tolerance of lactic acid bacterias for Folic acid–producing. The result showed that the ten of thirty six lactic acid bacterias could product Folic acid. C-17, CH-2 and C-25 had higher quantity of the Folic acid than others. According to the traditional morphological characters, physiological and biochemical properties, as well as chemical characteristics, C-17 was identificated as Lactobacillus plantarum, CH-2 was identificated as Lactobacillus acidophilus and C-25 was ident