發(fā)布時間：2018-04-20 04:06

  本文選題：鋅污染土壤 + 根際微生物　； 參考：《江南大學(xué)》2017年碩士論文

【摘要】：土壤重金屬污染已成為當(dāng)今面臨的主要環(huán)境問題之一,而重金屬污染土壤的植物修復(fù)技術(shù)因其成本投入較低、對土壤環(huán)境擾動小、不引起二次污染以及可美化景觀等特點成為當(dāng)前學(xué)術(shù)界研究的熱點。超積累植物被認為是實施重金屬污染環(huán)境植物修復(fù)不可缺少的材料。然而,大多數(shù)超積累植物生長周期長、生物量小,加上土壤中重金屬生物有效性低,嚴(yán)重限制了其應(yīng)用于大規(guī)模污染土壤修復(fù)的潛力。為了提高植物修復(fù)效率,接種根際微生物被認為是提高超積累植物修復(fù)效果的重要途徑。本研究從土壤中分離得到一株對重金屬鋅具有較強抗性且對難溶性鋅有促溶作用的菌株BC109-2,經(jīng)形態(tài)和分子生物學(xué)鑒定,確定其為一株微紫青霉菌,命名為Penicillium janthinellum BC109-2。鋅抗性菌株BC109-2對鋅的最小抑制濃度(MIC)達到2100 mg L-1,在PDB培養(yǎng)基(含1000 mg L-1 ZnCO3)中搖床振蕩培養(yǎng)72 h后,培養(yǎng)液中可溶性鋅含量增加了113%,該菌株對難溶態(tài)鋅具有較強的溶解作用。在篩選得到高鋅耐受性和溶解性菌株BC109-2的基礎(chǔ)上,對鋅在菌株細胞中的分布與化學(xué)形態(tài)進行分析并對細胞抗氧化系統(tǒng)進行毒性評價。菌株細胞中的鋅含量與培養(yǎng)基中的鋅濃度成正比;鋅由于強烈的陰陽離子相互作用結(jié)合到細胞壁上,占菌株細胞總鋅含量的14%~21%;液泡由于區(qū)室化作用可以作為毒性物質(zhì)的另一個存儲室,細胞液和液泡中的鋅含量占細胞總量的45%~49%。另外,細胞中的鋅大多以不溶態(tài)、草酸鹽態(tài)以及殘留態(tài)三種非活躍狀態(tài)存在。在不同濃度的鋅脅迫下的抗氧化酶活性的變化表明,鋅的加入會導(dǎo)致在真菌細胞中的氧化應(yīng)激響應(yīng),其中超氧化物歧化酶(SOD)、過氧化氫酶(CAT)、過氧化物酶(POD)三種抗氧化酶通過協(xié)調(diào)作用,直接參與清除細胞內(nèi)產(chǎn)生的活性氧自由基(ROS)的過程,且POD含量變化最為明顯;谷胱甘肽轉(zhuǎn)硫酶(GST)能催化還原型谷胱甘肽(GSH)和羥基自由基的結(jié)合而不產(chǎn)生氧化型谷胱甘肽(GSSG),但其活性增加并不明顯;除此之外,谷胱甘肽還原酶(GR)活性因為受到高濃度鋅脅迫而降低,導(dǎo)致GSH含量下降遠遠超過GSSG升高量。細胞可以通過抗氧化酶(SOD、CAT、POD、GR和GST)和非酶抗氧化劑(GSH和GSSG)的綜合作用使脂質(zhì)過氧化水平保持在一個相對穩(wěn)定的水平,以增強細胞抵御外界非生物刺激的能力,使細胞得以正常生長。最后對菌株BC109-2的促植物生長指標(biāo)進行評價,并研究供試菌株對印度芥菜修復(fù)鋅污染土壤的促進作用。鋅耐受菌株BC109-2能產(chǎn)吲哚乙酸(IAA)和鐵載體,并且具有ACC脫氨酶活性和溶磷能力,且能促進植物根系伸長;盆栽實驗結(jié)果表明,接種了根際促生菌的印度芥菜的地上部分對土壤中Zn的總提取量與不接種菌的對照組相比提高了42%,說明根際促生菌BC109-2可以促進印度芥菜吸收和富集土壤中的鋅,具有一定修復(fù)鋅污染土壤的應(yīng)用潛力。
[Abstract]:Soil heavy metal pollution has become one of the main environmental problems, and the phytoremediation technology of heavy metal contaminated soil has low cost and little disturbance to soil environment. The characteristics of not causing secondary pollution and beautifying landscape have become the focus of academic research. Superaccumulative plants are regarded as indispensable materials for phytoremediation of heavy metal polluted environment. However, the long growth cycle and small biomass of most superaccumulative plants, coupled with the low bioavailability of heavy metals in soil, seriously limit their potential for remediation of contaminated soils on a large scale. In order to improve the efficiency of phytoremediation, inoculation of rhizosphere microorganisms is considered to be an important way to improve the effect of hyperaccumulative phytoremediation. In this study, a strain BC109-2 with strong resistance to heavy metal zinc and solubilization of insoluble zinc was isolated from soil. The strain BC109-2 was identified as Penicillium janthinellum BC109-2 by morphological and molecular biological identification. The minimum inhibition concentration of zinc resistance strain BC109-2 was 2100 mg L -1. After shaking culture in PDB medium (containing 1000 mg L -1 ZnCO 3) for 72 h, the soluble zinc content in the culture medium increased by 113%, and the strain had a strong dissolution effect on insoluble zinc. On the basis of screening high zinc tolerance and solubility strain BC109-2, the distribution and chemical forms of zinc in the strain cells were analyzed and the cytotoxicity of the antioxidant system was evaluated. The content of zinc in the cell of the strain is proportional to the concentration of zinc in the medium; zinc is bound to the cell wall because of the strong interaction of anion and anion. The vacuoles can be used as another storage room for toxic substances because of the compartmentalization of the vacuoles, and the zinc content in the cell fluid and vacuole accounts for 4549% of the total number of cells. In addition, most of the zinc in cells were insoluble, oxalate and residual states. The changes of antioxidant enzyme activity under different concentrations of zinc stress showed that the addition of zinc resulted in oxidative stress response in fungal cells. Superoxide dismutase (SOD), catalase catalase (cat) and peroxidase (POD) were involved in the process of scavenging the reactive oxygen free radicals (Ros) by coordinating action, and the change of POD content was the most obvious. Glutathione transferase (GST) can catalyze the binding of reduced glutathione glutathione (GSH) with hydroxyl radical without producing oxidized glutathione GSSGN, but its activity increase is not obvious. Glutathione reductase (Glutathione reductase) activity decreased due to high concentration of zinc stress, resulting in the decrease of GSH content far more than the increase of GSSG. Cells can maintain the level of lipid peroxidation at a relatively stable level through the combined effects of antioxidant enzymes such as SOD, CAT, PODN, gr and GST, and non-enzymatic antioxidants, GSH and GSSGG, in order to enhance the ability of cells to resist external abiotic stimuli and to make the cells grow normally. Finally, the plant growth index of strain BC109-2 was evaluated, and the promoting effect of the strain on the remediation of zinc contaminated soil by Indian mustard was studied. Zinc tolerant strain BC109-2 can produce indoleacetic acid (IIA) and iron carrier, and it has the activity of ACC deaminase and the ability of dissolving phosphorus, and can promote the elongation of plant root system. The total amount of Zn extracted from soil by the aboveground part of Indian mustard inoculated with rhizosphere growth promoting bacteria increased 42 ~ 2% compared with that of the control group without inoculation, which indicated that BC109-2 could promote the absorption and accumulation of zinc in soil by Indian mustard (Brassica juncea). It has the potential of remediation of zinc contaminated soil.
【學(xué)位授予單位】：江南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X53;X172

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本文編號：1776150