青藏高原不同材料来源乳酸菌极端环境耐受性及优良菌株益生性的初步研究

发布时间：2018-04-25 14:49

  本文选题：青藏高原 + 乳酸菌　； 参考：《郑州大学》2017年硕士论文

【摘要】：本研究以青藏高原地区裸鲤肠道、植物表面、土壤为研究材料,对其附着乳酸菌代表株在极端环境条件下的耐受性进行检测,探讨不同材料来源乳酸菌极端环境耐受性的差异,并对部分优良乳酸菌代表株的益生性能进行初步研究,以期筛选具有益生潜能的乳酸菌。依照乳酸菌形态特征、生理生化特点,结合16S rRNA基因序列分析,不同年龄的裸鲤肠道附着乳酸菌大致被归为4个属,分别是Lactobacillus、Leuconostoc、Lactococcus和Pediococcus,分属8个种主要为lactococcus lactis、pediococcus acidilactici、pediococcus pentosaceus、leuconostoc mesenteroides、lactobacillus paraplantarum、lactobacillus sakei、lactobacillus fuchuensis、lactobacillus casei等,其中杆菌明显比比球菌多。分别从裸鲤肠道、植物表面、茶卡盐湖土壤分离乳酸菌中选择48株乳酸菌代表株进行极端环境耐受性的检测。通过平板计数法以及比浊度来检测乳酸菌在极低pH、高盐浓度、极端温度条件下的生长状况。结果发现所有乳酸菌在pH1的极酸环境下都不能存活,大部分乳酸菌在pH2的酸性环境中的生长明显受到抑制,部分存活率达到70%,其中裸鲤肠道分离菌F2-2、F9-10、F12-66能够生长,显示极强的酸性耐受性,pH3的酸性环境下存活率普遍较高,甚至还能生长。在16%的高盐浓度下,多株乳酸菌存活率可达到50%以上,部分能够生长。50℃高温对乳酸菌的生存造成了严重的威胁,大多数乳酸菌不能存活,只有极少数乳酸菌能够在培养的前12个小时得以缓慢的生长。大多数乳酸菌在10℃的低温条件下都能够良好生长,0℃条件下几乎不能生长,但F2-1、F11-67、M1-8在培养168h后,OD值达到0.35,表现出缓慢的生长趋势,其中2株为P.pentosaceus。通过纸片扩散法、平板计数法检测乳酸菌代表株抗生素敏感性以及对胃肠道环境的耐受性。结果显示乳酸菌主要对VA、GM、PB、CIP、PG有抗性,对CHL、AM、TE较为敏感。多数乳酸菌对胃肠道环境耐受性比较差,经过7h的人工模拟胃肠道环境后乳酸菌存活率比较低甚至全部死亡,其中N20、N7、N6、N1、qz1242耐受性比较强,存活率最高为61.11%,最低为31.95%,并且可以发现耐受性比较好的菌株大多数为Lactobacillus,其中存活率最高的为分离自土壤中的L.plantarum。人工模拟胃肠道耐受性比较好的乳酸菌通过平板计数法来检测不同胆盐浓度下的耐受性。胆盐对乳酸菌的生长显示出抑制性,并且随其浓度的增加及培养时间的延长而逐渐增强。在0.1%的胆盐浓度下,乳酸菌的存活率比较高,甚至高达100%,小部分乳酸菌能够在含0.2%的胆盐培养基中存活,随着胆盐浓度增加到0.3%,大多数乳酸菌的存活率直线下降为0,耐受性极差。茶卡盐湖土壤分离乳杆菌N22、N19在0.3%的胆盐浓度下4h活菌数为2.70 logcfu/ml,具有一定强度的胆盐耐受性。
[Abstract]:In this study, the intestinal tract, plant surface and soil of naked carp in Qinghai-Xizang Plateau were used as the research materials, the tolerance of the representative strains of lactic acid bacteria attached to them under extreme environmental conditions was tested, and the differences of extreme environmental tolerance of lactic acid bacteria from different sources were discussed. The probiotics of some representative strains of lactic acid bacteria were studied in order to screen lactic acid bacteria with probiotic potential. According to the morphological characteristics, physiological and biochemical characteristics of lactic acid bacteria and the sequence analysis of 16s rRNA gene, four genera of Lactobacillus leuconostoctus Lactococcus and Pediococcus. belong to 8 species of lactococcus lactis, mainly lactococcus acidilacticipestris pentosaceus pentosaceus Lactobacillus mesenteroideslactobacillus paraplantarum lactobacillus lactobacillus lactobacillus sakeilactobacillus fuchuensis lactobacillus casei. There were more bacilli than cocci. 48 representative strains of lactic acid bacteria were selected from the intestinal tract, plant surface and tea salt lake soil of naked carp to detect their extreme environmental tolerance. The growth of lactic acid bacteria at very low pH, high salt concentration and extreme temperature was detected by plate counting and turbidity. The results showed that all lactic acid bacteria could not survive in the extreme acid environment of pH1. The growth of most lactic acid bacteria in the acidic environment of pH2 was obviously inhibited, and the partial survival rate reached 70%, in which the isolated bacteria F2-2F9-10F12-66 from the intestine of naked carp could grow. The results showed that the survival rate of pH 3 was higher than that of pH 3, and it could even grow. Under the high salt concentration of 16%, the survival rate of many strains of lactic acid bacteria could reach more than 50%, and some of them could grow at 0.50 鈩，

本文编号：1801787