兰州大学机构库 >生命科学学院
一株传统发酵牦牛酸奶源产Ⅱa类细菌素德氏乳杆菌及其生物学特性研究
Alternative TitleStudy on the biological characteristics of a class Ⅱa bacteriocin-producing Lactobacillus delbrueckii isolated from traditional fermented yak milk
朱婕旭
Thesis Advisor郭旭生
2019-03-01
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Degree Discipline生态学
Keyword牦牛酸奶 乳酸菌 Ⅱa类细菌素 葡萄
Abstract青藏高原,其独特的地理地貌造就了当地的极端环境。因此,青藏高原的传统发酵牦牛酸奶中,蕴藏着的乳酸菌具备了特殊的生物性功能。Ⅱa类细菌素,不单单可以抑制革兰氏阳性细菌的繁殖,同时对革兰氏阴性细菌也有一定的抑制作用。由于Ⅱa 类细菌素主要来源于食品级的微生物且具有抗李斯特菌和金黄色葡萄球菌的标志性抑菌能力,又使其能够发展成为天然生物性防腐剂。本论文主要通过菌落PCR法快速筛选得到一株产Ⅱa类细菌素的德氏乳杆菌,并对得到的乳酸菌及其所产细菌素进行了生物学特性研究,之后对筛选出的乳酸菌在葡萄保鲜中的应用进行了研究。研究结果如下:1. 采用PCR快速筛选方法,对实验室分离保存的127株来自青藏高原传统发酵牦牛乳中的乳酸菌进行产Ⅱa类细菌素的筛选,得到了1株产Ⅱa类细菌素的德氏乳杆菌F17,并用传统的琼脂扩散法进行了验证。2. 通过对所产细菌素进行生物学特性研究,得出以下结论,其最适温度为37℃,热稳定性较好。最适pH为6.0,耐酸、耐碱特性较好。对α-淀粉酶不敏感,能够被木瓜蛋白酶、蛋白酶K、胃蛋白酶和胰蛋白酶水解。3. 通过对筛选得到的产Ⅱa类细菌素的德氏乳杆菌F17的理化特性进行研究,发现该株菌在较低温的10℃和15℃、偏酸性的pH3.5、偏碱性的pH9.0及8%浓度NaCl等条件下均能正常生长,表现出了较强的适应性。并且F17对糖源的利用能力比较广泛,生长能力强,产酸速度快,是性状优良的乳酸菌。4. 通过对筛选得到的产Ⅱa类细菌素的乳酸菌F17在葡萄保鲜中的作用进行研究,发现F17所产细菌素能明显抑制微生物生长,降低葡萄的失重率、褐变率及腐败率。能延缓葡萄有机酸含量到达高峰的时间,维持葡萄的可溶性固形物含量的稳定,并且通过测定总酚含量发现其对葡萄起到了抗氧化的作用。综上说明F17能够延长葡萄的贮藏期,对葡萄具有一定的保鲜作用。
 
Other AbstractBecause of the extreme environment in Qinghai-Tibet Plateau, lactic acid bacteria isolated from traditional fermented yak yoghurt in that area are proposed to have special properties. Class IIa bacteriocin has great potential to be applied in food not noly for its inhibition on Gram-positive and Gram-negative bacteria, especially for Listeria and Staphylococcus aureus, but also for its safety as it is produced by food-grade microbes. In this thesis, a class IIa bacteriocin-producing lactic acid bacteria of Lactobacillus delbrueckii was screened by using colony PCR and agar disffusion methods. The characteristics of the selected strain and its effects on grape preservation were studied subsequently. The research results are as follows: 1. From 127 strains of lactic acid bacteria isolated from the traditional fermented yak yoghurt in the Qinghai-Tibet Plateau, and one strain of Lactobacillus delbrueckii F17 with ability of producing class IIa bacteriocin was selected though specific PCR. The antibactria ability of F17 was verified again according to the method of agar disffusion method. 2. Through the study of the biological characteristics of the bacteriocin, it was found that the optimum temperature for taking function was 37 °C, and it had good thermal stability. The optimum pH was 6.0, and it had good acid and alkali resistance. The produced bacteriocin could be hydrolyzed by papain, proteinase K, pepsin and trypsin wheras not sensitive to alpha-amylase. 3. By studying the physicochemical properties of the class IIa bacteriocin-producing Lactobacillus delbrueckii F17, it was found that the strain has strong tolerance to the growth environment. It could grow at the lower temperature of 10 °C and 15 °C, and at the pH 3.5, pH 9.0 and 8% NaCl can also grow normally and show strong adaptability. Additionally, the strain of F17 has a fast acid-producing rate, strong growth ability, and extensive utilization of sugar sources. 4. Through the study on the role of F17 in grape preservation, it was found that the bacteriocin produced by F17 can significantly inhibit the growth of microorganisms and reduce the weight loss, the rates of corruption and browning of grapes. It can delay the time when the grape organic acid content reaches the peak, maintain the stability of the soluble solid content of the grape. In addition, the strain F17 was proved to haves an antioxidant effect on the grape by measuring the total phenolic content. Overall, F17 can prolong the storage period of grapes and have a certain preservation effect on grapes.
Pages53
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.lzu.edu.cn/handle/262010/342014
Collection生命科学学院
Affiliation生命科学学院
Recommended Citation
GB/T 7714
朱婕旭. 一株传统发酵牦牛酸奶源产Ⅱa类细菌素德氏乳杆菌及其生物学特性研究[D]. 兰州. 兰州大学,2019.
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