植物促生细菌Rhizobium sp. T1-17对蔬菜重金属消减作用的效果及其机制研究

发布时间：2018-05-25 03:16

本文选题：重金属污染土壤 + 植物促生细菌　；参考：《南京农业大学》2015年硕士论文

【摘要】：土壤重金属污染的微生物修复是一种环境友好、易于操作且成本较低的修复技术。微生物能够通过多种方式促进植物的生长及植物对重金属的耐受性、降低重金属的生物有效性;草炭、蛭石等有机土壤改良剂能够通过对重金属元素的吸附作用减少重金属向植物中的转移,将微生物与这些改良剂结合制备成固体菌剂能够有效结合二者的作用,能有效减少重金属的植物吸收,实现污染土壤的安全利用。通过耐重金属植物促生菌的筛选,可以丰富植物生长促进细菌的菌种资源,为污染土壤的安全利用改进的材料。本文中从栖霞山铅锌矿区和汤山铜矿区附近土样样品和植物样品中分离得到细菌共220株;通过测定细菌产吲哚乙酸和铁载体的促生特性,筛选得到了 78株产吲哚乙酸细菌、19株产铁载体细菌,其中同时具备多种重金属抗性和植物促生特性的细菌共计84株。结合上述细菌的促生特性、重金属抗性以及16S rRNA基因的系统发育地位,选择 6 株菌(Pseudomonas sp.G4-19,Bacillus sp.Q20,Paenibacillus qingshengii S1-9,Pseudomonas sp.S1-16,Chryseobacterium sp.T1-6,Rhizobium sp.T1-17)进行短期盆栽试验,以市面上常见的青梗菜、辣椒和杨花萝卜为供试蔬菜,以栖霞山原位污染土壤为供试土壤,研究6株供试菌株对蔬菜幼苗生长和重金属含量的影响。结果表明,只有菌株T1-17能够促进三种蔬菜幼苗生物量的积累,同时降低其重金属含量。菌株T1-17能够使青梗菜和杨花萝卜生物量分别提高64.6%和127.3%,对辣椒幼苗的生物量无显著影响;同时菌株T1-17使青梗菜、辣椒、杨花萝卜中Cd浓度分别下降22.1%、26.7%和33.4%,Pb浓度下降59.1%、15.5%、44.0%。将功能菌株T1-17与吸附剂蛭石、草炭和生物炭相结合,制备成固体菌剂,探究功能菌株、吸附剂及不同菌剂对蔬菜产量和蔬菜果实中重金属含量的影响。结果表明不同处理均能够增加三种蔬菜的产量,增加比例为37.0%-334.1%;同时降低蔬菜食用部分重金属含量,Cd浓度下降11.9%-82.5%,Pb浓度下降24.6%-87.3%。不同处理之间的效果表现为:固体菌剂功能菌株吸附剂。通过检测,功能菌株T1-17能够稳定定殖于盆栽土壤中。与接灭活菌对照相比,添加功能菌株、吸附剂及固体菌剂等不同处理显著增加了青梗菜和辣椒叶片的叶绿素含量;同时显著增加了根际土中有机质的含量,增加比例为39.6%-455.6%;根际土中产吲哚乙酸和产铁载体细菌的比例也表现为增加趋势。这可能解释了不同处理能够增加蔬菜幼苗生物量、提高蔬菜产量的可能机制。除此之外,不同处理还显著降低了盆栽根际土壤中水溶态、交换态、提取态三种有效态重金属的浓度;对盆栽土壤的团聚体结构分析表明,不同处理还促使了大颗粒团聚体(2 mm)分解转化为微团聚体颗粒(0.25 mm),增加了重金属离子在土壤颗粒的吸附能力,这表明本文中不同处理可能是通过对重金属进行吸附和转化等作用降低了重金属的生物活性,从而减少了蔬菜的重金属吸收。
[Abstract]:Microbial remediation of heavy metals contaminated soil is a kind of environmentally friendly, easy to operate and low-cost remediation technology. Microbes can promote plant growth and plant tolerance to heavy metals in a variety of ways, and reduce the bioavailability of heavy metals. Turf, vermiculite and other organic soil improver can be used to absorb heavy metals. It can reduce the transfer of heavy metals to plants. The combination of microorganism and these modifiers can effectively combine the effect of the two. It can effectively reduce the plant absorption of heavy metals and realize the safe utilization of contaminated soil. Through the screening of heavy metal resistant plants, it can enrich plant growth and promote bacterial strain. In this paper, 220 strains of bacteria were isolated from the samples of soil samples and plant samples near the Qixia mountain lead zinc mining area and the Tangshan copper mine area, and 78 strains of indolic acetic acid producing bacteria and 19 strains of ferric carrier bacteria were screened by measuring the growth promoting characteristics of indoles acetic acid and iron carrier. At the same time, there are 84 strains of bacteria with a variety of heavy metal resistance and plant growth promoting characteristics. Combined with the growth promoting characteristics of the above bacteria, heavy metal resistance and the phylogenetic status of the 16S rRNA gene, 6 strains of bacteria (Pseudomonas sp.G4-19, Bacillus sp.Q20, Paenibacillus qingshengii S1-9, Pseudomonas sp.S1-16, Chryseobacterium) are selected. Rhizobium sp.T1-17) carried out a short-term pot experiment with the common green stem, chili and poplar radish on the market as the tested vegetables. The soil of Qixia mountain in situ contaminated soil was used as the tested soil. The effects of 6 strains of strain on the growth of vegetable seedlings and heavy metal content were studied. The results showed that only the strain T1-17 could promote the biomass of three kinds of vegetable seedlings. The strain T1-17 could increase the biomass of green stem and poplar radish by 64.6% and 127.3% respectively, and had no significant effect on the biomass of pepper seedlings. At the same time, the strain T1-17 made the concentration of Cd in green stem, chili and poplar radish decreased by 22.1%, 26.7% and 33.4% respectively, and the concentration of Pb decreased by 59.1%, 15.5%, and 44.0%.. Strain T1-17 was combined with adsorbent vermiculite, peat and biological charcoal to prepare solid bacteria to explore the effects of functional strains, adsorbents and different bacteria on the content of heavy metals in vegetable yield and vegetable fruit. The results showed that the yield of three vegetables could be increased by different treatments, the increase was 37.0%-334.1%, and the edible part of vegetable was reduced. The content of heavy metals, Cd concentration decreased 11.9%-82.5%, Pb concentration decreased, and the effect of different treatment of 24.6%-87.3%. showed that the functional strain of solid bacteria was adsorbent. The functional strain T1-17 could be steadily colonized in the potted soil. Compared with the control of the inactivated bacteria, the functional strains, adsorbents and solid fungi were treated with different treatments. The content of chlorophyll in green stem and pepper was increased, and the content of organic matter in rhizosphere soil increased to 39.6%-455.6%, and the proportion of indolic acetic acid and ferric carrier bacteria in rhizosphere soil was also increased. This may explain that different treatments can increase the biomass of vegetable seedlings and increase vegetable yield. In addition to this, different treatments also significantly reduced the concentration of water soluble, exchangeable, and extracted three active heavy metals in the rhizosphere soil of potted plants, and the aggregate structure analysis of potted soil showed that different treatments also promoted the transformation of large particle aggregates (2 mm) into micro aggregate particles (0.25 mm), and increased heavy metals. The adsorption capacity of ions in soil particles shows that different treatments may reduce the bioactivity of heavy metals by adsorption and transformation of heavy metals, thus reducing the absorption of heavy metals in vegetables.
【学位授予单位】：南京农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X17;S63

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