發(fā)布時(shí)間：2017-12-28 02:09

  本文關(guān)鍵詞：土壤礦物介導(dǎo)下細(xì)菌生物膜形成過程及機(jī)制　出處：《華中農(nóng)業(yè)大學(xué)》2017年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 土壤礦物 細(xì)菌 生物膜

【摘要】：生物膜作為細(xì)菌存在于自然界生物體或非生物體表面的重要形態(tài),其在醫(yī)學(xué)、工業(yè)以及農(nóng)業(yè)上的影響和作用受到廣泛的重視。作為地球上最普遍的一種生命形式,生物膜可通過形成的胞外聚合物(EPS)使微生物獲得競(jìng)爭性優(yōu)勢(shì),如加強(qiáng)了生物膜內(nèi)微生物之間群體感應(yīng)效應(yīng)、幫助細(xì)胞在表面定殖和互養(yǎng)共生、保護(hù)細(xì)胞防止被捕食、抵抗干旱、減少污染物對(duì)細(xì)胞的毒性等。土壤中微米和納米級(jí)礦物由于比表面積大、電荷密度高,表面富含離子、水分及其它營養(yǎng)物質(zhì),常與微生物結(jié)合在一起,在土壤生物地球化學(xué)界面的形成、結(jié)構(gòu)調(diào)控、活性和功能發(fā)揮等方面具有重要的作用。然而,到目前為止,從生物膜角度研究細(xì)菌與土壤礦物相互作用還比較少見。本文以土壤中常見的礦物和微生物為供試材料,借助激光共聚焦顯微鏡(CLSM)、原子力顯微鏡(AFM)、衰減全反射傅里葉變換紅外光譜(ATR-FTIR)和q-PCR等現(xiàn)代儀器分析技術(shù),研究了土著細(xì)菌游離態(tài)細(xì)胞與生物膜細(xì)胞表面性質(zhì)的差異,以及土壤典型礦物對(duì)細(xì)菌生物膜形成的影響,獲得如下主要結(jié)果:(1)明晰了土著細(xì)菌游離態(tài)細(xì)胞與生物膜細(xì)胞之間的表面性質(zhì)差異。惡臭假單胞菌成膜速度快,生物膜周期為24 h,而枯草芽孢桿菌的生物膜周期為72 h;細(xì)菌在形成生物膜后,細(xì)胞的尺寸變小、細(xì)胞形狀由桿狀變?yōu)闄E球形,細(xì)胞的疏水性增強(qiáng),表面帶電量增多、電負(fù)性增強(qiáng);與游離態(tài)細(xì)胞相比,生物膜細(xì)胞表面官能團(tuán)的種類不發(fā)生改變,但是表面官能團(tuán)的濃度會(huì)增加。(2)探明了土壤中典型的粘土礦物(蒙脫石和高嶺石)以及鐵氧化物(針鐵礦)對(duì)土壤中常見的細(xì)菌(枯草芽孢桿菌)生物膜形成的影響機(jī)制。實(shí)驗(yàn)結(jié)果表明,在針鐵礦體系中,生物膜在48 h時(shí)生物量達(dá)到最大值,而蒙脫石和高嶺石體系中生物膜生物量在60 h達(dá)到最大。激光共聚焦顯微鏡觀察到48 h時(shí)針鐵礦體系中形成了致密、具有多層細(xì)胞的生物膜。細(xì)菌與礦物作用4 h后,針鐵礦體系中細(xì)胞失活率高達(dá)60%,其次是高嶺石和蒙脫石。原子力顯微鏡結(jié)果顯示細(xì)菌與針鐵礦之間發(fā)生緊密吸附,針狀的針鐵礦可以刺破細(xì)胞壁,細(xì)胞感應(yīng)到不利環(huán)境,通過調(diào)控枯草芽孢桿菌生物膜形成的兩個(gè)主要基因abrB和sinR,使細(xì)胞傾向于向氣液表面運(yùn)動(dòng)并聚集形成生物膜。礦物的理化性質(zhì)是礦物影響細(xì)菌形成生物膜的主導(dǎo)因素。(3)明確了不同濃度的典型土壤金屬氧化物(針鐵礦、勃母石和水鈉錳礦)對(duì)惡臭假單胞菌生長及生物膜形成的影響機(jī)制。當(dāng)針鐵礦濃度為1~100 mg L-1時(shí),可以促進(jìn)惡臭假單胞菌的生長和生物膜的形成,而針鐵礦濃度為100~500 mg L-1時(shí),會(huì)抑制細(xì)菌的生長和生物膜的形成;當(dāng)勃姆石濃度低于20 mg L-1時(shí)可促進(jìn)細(xì)菌的生長和生物膜的形成,20~500 mg L-1勃姆石會(huì)抑制惡臭假單胞菌的生長和生物膜的形成;不同濃度的水鈉錳礦對(duì)惡臭假單胞菌的生長沒有影響,但是會(huì)抑制細(xì)菌生物膜的形成。原子力顯微鏡圖像顯示,針鐵礦表面細(xì)菌的細(xì)胞膜被刺破,細(xì)胞完整性受損;勃姆石表面細(xì)胞發(fā)生了溶解;水鈉錳礦表面細(xì)胞粒徑變小、表面褶皺增加。不同土壤金屬氧化物與細(xì)菌相互作用的強(qiáng)度和沉降能力是影響惡臭假單胞菌生物膜形成的關(guān)鍵因素。生物膜中的EPS可以顯著的提高惡臭假單胞菌對(duì)礦物的耐受能力。
[Abstract]:Biofilm as an important form of bacteria exists on the surface of natural organisms or non organisms, and its influence and function in medicine, industry and agriculture has been widely valued. As one of the most common form of life on earth, biological membrane can be formed by extracellular polymers (EPS) enable the microorganism to gain a competitive advantage, such as strengthen the biofilm microbial community, help cells in the induction effect of surface colonization and syntrophic symbiosis, protect cells to prevent predation, drought resistance, reduce on the cell toxicity of pollutants. The soil in the micron and nano minerals due to large surface area, high charge density, the surface is rich in ion and water and other nutrients, and microbes together in formation, soil biogeochemical interface structure, activity and function regulation play an important role. However, so far, it is rare to study the interaction between bacteria and soil minerals from the biofilm angle. In this paper, the soil minerals and microorganisms in common as tested materials, using laser scanning confocal microscope (CLSM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and q-PCR and other modern instrument analysis technology, studied the indigenous bacterial free surface properties of cells and cell membrane biological state difference well, the influence of soil minerals on the typical bacterial biofilm formation, the main results are as follows: (1) clear differences between the surface properties of indigenous bacteria free cells and biofilm cells. Pseudomonas putida film speed, biofilm cycle is 24 h, and the biofilm cycle of Bacillus subtilis was 72 h; bacteria in biofilm formation, cell size, cell shape by baculovirus to ellipsoid, the cell hydrophobicity enhancement, surface charge quantity and electronegativity enhanced; compared with free cells, types of biofilm cells and surface functional groups are not changed, but the concentration of surface functional groups will increase. (2) the influence mechanism of typical clay minerals (montmorillonite and kaolinite) and iron oxide (goethite) on biofilm formation of soil bacteria (Bacillus subtilis) was explored. The experimental results showed that in the goethite system, the biomass reached the maximum value at 48 h, while the biomass of montmorillonite and kaolinite reached the maximum at 60 h. A compact, multi-layer cell membrane was formed in the 48 h clockwise iron ore system by laser confocal microscopy. After 4 h of the bacteria and minerals, the cell deactivation rate of the goethite system was 60%, followed by kaolinite and montmorillonite. Atomic force microscopy results show close adsorption between bacteria and goethite, acicular goethite can pierce the cell wall, cell induction to the adverse environment, two major genes abrB and sinR formed by regulating the Bacillus subtilis biofilm, biofilm formation in the cells tend to gas-liquid surface movement and aggregation. The physicochemical properties of minerals are the dominant factors that affect the formation of biofilms by minerals. (3) the influence mechanism of typical soil metal oxides of different concentrations (goethite, boomite and sodium manganese ore) on the growth and biofilm formation of Pseudomonas putida was clarified. When the concentration of 1~100 mg L-1 goethite, can promote the growth and biofilm formation of Pseudomonas putida, and goethite concentration was 100~500 mg L-1, the growth and biofilm formation will be inhibited; when the formation of boehmite concentration lower than 20 mg L-1 can promote bacterial growth and biofilm. The formation, growth and biofilm 20~500 mg L-1 boehmite can inhibit Pseudomonas putida; did not affect the growth of birnessite with different concentration on Pseudomonas putida, but can inhibit the formation of bacterial biofilm. Atomic force microscopy images show that the cell membrane of bacteria on the surface of the iron needle was punctured, the damaged cell integrity; the dissolution of boehmite surface cells; sodium manganese cell surface has smaller particle size, surface fold increase. The strength and settling capacity of the interaction of different soil metal oxides and bacteria is the key factor affecting the formation of Pseudomonas aeruginosa biofilm. The EPS in the biofilm can significantly improve the tolerance of Pseudomonas stinosa to mineral.
【學(xué)位授予單位】：華中農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：S154.3;S153.6

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 郭嘉亮;陳衛(wèi)民;;細(xì)菌群體感應(yīng)信號(hào)分子與抑制劑研究進(jìn)展[J];生命科學(xué);2007年02期

相關(guān)博士學(xué)位論文 前3條

1 高坦坦;芽胞桿菌生物膜形成機(jī)制研究[D];中國農(nóng)業(yè)大學(xué);2015年

2 曹媛媛;細(xì)菌胞外聚合物與土壤固相界面作用機(jī)理及其環(huán)境效應(yīng)[D];華中農(nóng)業(yè)大學(xué);2013年

3 陳光村;惡臭假單胞菌CZ1非飽和生物膜耐受和累積重金屬的分子機(jī)制[D];浙江大學(xué);2011年

相關(guān)碩士學(xué)位論文 前1條

1 謝俊;大腸桿菌O157:H7對(duì)不同土壤礦物響應(yīng)的分子生物學(xué)機(jī)制[D];華中農(nóng)業(yè)大學(xué);2015年

，

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