Knowledge Resource Center for Ecological Environment in Arid Area
| 荒漠土壤中抗氧化细菌的筛选及其抗氧化机制研究 | |
| 其他题名 | Screening of Antioxidant Active Bacteria in Desert Soil and Its Anti-oxidation Mechanism |
| 李婷 | |
| 出版年 | 2018 |
| 学位类型 | 硕士 |
| 导师 | 刘光琇 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 荒漠蕴藏大量的微生物资源。作为荒漠生态系统重要组成部分，微生物参与和主导了重要的生态过程，对于稳定荒漠生态系统、完善生态功能有重要意义。然而荒漠环境条件恶劣，微生物在该系统内生存经常面临多重胁迫，包括干旱、高温、UV辐射等。这些环境胁迫使得荒漠土壤微生物体内外积累大量的超氧离子或过氧化物，抑制其生长或者直接造成死亡。探究荒漠土壤微生物的抗氧化机制，可为荒漠地区抗氧化资源的开发提供科学依据和技术基础。本文以荒漠土壤微生物为研究对象，通过氧化筛选、酶活性测定、转录组测序分析等手段，对荒漠土壤微生物抗氧化特性以及抗氧化途径进行了研究。取得了如下结论： 1. 在我国柴达木盆地、腾格里沙漠，智利阿塔卡马沙漠，南极Lake Vida以及美国死亡谷的badwater土样中分离得到11株抗逆活性较高的细菌，利用不同浓度的过氧化氢对所有菌株作瞬时氧化处理，结果显示11株菌株中海床动性微菌AX6（Planomicrobium okeanokoites AX6）与海洋考克氏菌KD4（Kocuria marina KD4）在3mM过氧化氢浓度中存活率仍然可达80%，虽然经氧化胁迫产生了细胞膜损伤，但损伤程度显著低于来源自普通土壤环境中的菌株。表明菌株AX6与KD4具有较强的抗氧化能力。2.对抗氧化活性突出的菌株AX6与KD4进行过氧化氢处理后测定其抗氧化酶活性变化特征。结果显示，经氧化胁迫后菌株抗氧化酶活性发生显著变化。其中，菌株AX6的谷胱甘肽过氧化物酶活性显著升高，同时DPPH、超氧阴离子自由基的清除能力提高。菌株KD4经氧化胁迫后过氧化氢酶活性显著升高，对超氧阴离子自由基、羟基自由基的清除能力提高。说明菌株AX6与KD4在受到过氧化氢氧化胁迫时过氧化氢分解类酶均升高。同时，不同菌株亦在其抗氧化酶种类、自由基清除能力展现出差异。3. 选取本研究中抗氧化活性最高的菌株AX6进行转录组分析，测序结果显示菌株可通过上调胞内物质转运、合成以及新陈代谢过程相关基因的表达来应对氧化胁迫。其中，包括类胡萝卜素合成有关基因、谷胱甘肽代谢相关基因、叶酸合成基因、B族维生素合成相关基因、DNA修复相关基因、抗生素合成基因、调节渗透相关基因与产孢子基因等。这表明在氧化胁迫下，菌株AX6可以通过DNA修复功能来降低氧化环境造成的遗传物质损伤，加强B族维生素合成、类胡萝卜素合成以及谷胱甘肽代谢来清除细胞内多余的活性氧。同时，氧化胁迫还引起AX6渗透调节和休眠基因的表达增加。 |
| 英文摘要 | The desert contains a lot of microbial resources. As an important part of the desert ecosystem, micro-organisms participate in and dominate important ecological processes, which are important for stabilizing the desert ecosystem and improving ecological functions. However, with the harsh desert environment, microorganisms often face multiple stresses in this ecosystem, including drought, high temperature, UV radiation and so on. These environmental stresses cause the microbes in desert soils to accumulate a large amount of superoxide anion radical or peroxides in and outside the body, inhibiting their growth or causing death directly. Exploring the anti-oxidation mechanism of microbes in desert soils can provide scientific basis and technological basis for the development of antioxidant resources in desert areas.In this paper, the microbes in desert soils as the research object, through oxidation screening, enzyme activity assay, transcriptome analysis and other means to study the antioxidant properties of bacteria in desert soils and antioxidant pathways. The following conclusions have been made:1. Eleven strains of bacteria with high were isolated in the Qaidam Basin, Tengger Desert in China, the Atacama Desert in Chile, the Lake Vida in Antarctica, and the badwater soil in the Death Valley in the United States. All strains were treated instantaneously with different concentrations of hydrogen peroxide.. The results showed that in 3mM hydrogen peroxide concentration, the viability of comparable between Planomicrobium okeanokoites AX6 and Kocuria marina KD4 in 11 strains were up to 80%, although the cell damage caused by oxidative stress, its degree is significantly lower than the strains in the general environment. It showed that strains AX6 and KD4 have strong antioxidant capacity.2. The changes of of the strains AX6 and KD4 antioxidant enzyme activity were determined after hydrogen peroxide treatment. The results showed that the glutathione peroxidase activity of strain AX6 increased significantly after oxidative stress, and DPPH, superoxide anion free radical scavenging capacity is increased. The catalase activity of strain KD4 was significantly increased after oxidative stress, and its ability to scavenge superoxide anion radicals and hydroxyl radicals is increased. The results showed that the hydrogen peroxide decomposition enzymes of strains AX6 and KD4 were increased when they were subjected to hydrogen peroxide stress. At the same time, strains from different sources also showed differences in their antioxidant enzyme type and free radical scavenging capacity.3. The results of transcriptome sequencing of AX6 strain showed that in the oxidative environment, the expression of genes related to substance transport, synthesis, and metabolism of the strain was up-regulated. Including carotenoid synthesis related genes, glutathione metabolism related genes, folic acid synthesis genes, B vitamin synthesis related genes, and DNA repair related genes, antibiotic synthesis genes, regulation of infiltration related genes and sporulation genes. Those show that under oxidative stress, strain AX6 can reduce the damage of genetic material caused by oxidative environment through DNA repair function, strengthen the synthesis of B vitamins, carotenoid synthesis and glutathione metabolism to eliminate excess reactive oxygen species in cells. At the same time, oxidative stress also caused an increase in AX6 osmoregulation and secondary metabolites. |
| 中文关键词 | 荒漠土壤细菌 ; 抗氧化 ; 生理生化机制 ; 转录组 |
| 英文关键词 | Bacteria in desert soils Antioxidant Physiological mechanism Transcriptome |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288124 |
| 推荐引用方式 GB/T 7714 | 李婷. 荒漠土壤中抗氧化细菌的筛选及其抗氧化机制研究[D]. 中国科学院大学,2018. |
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