【作者】 王静；

【导师】 曾光明；

【作者基本信息】 湖南大学 ， 环境工程， 2010， 硕士

【摘要】 生物表面活性剂在土壤修复中强化微生物降解疏水性有机污染物的方式之一是增强微生物菌体表面的疏水性,以促进土壤中的微生物菌体和污染物的直接接触,从而加速污染物的降解。但是我们尚不清楚生物表面活性剂与微生物菌体之间的作用方式以及菌体在生物表面活性剂的作用下其表面性质的变化规律。本文系统地研究探讨了生物表面活性剂鼠李糖脂以及其它类型的表面活性剂对菌体降解不同性质的碳源的影响。首先我们通过铜绿假单胞菌的好氧发酵制取了生物表面活性剂鼠李糖脂,并通过酸沉降和柱层析对其进行提纯,最后得到纯化了的鼠李糖脂单糖脂和鼠李糖脂二糖脂。液质联用的结果表明,这两种鼠李糖脂主要含有三种成分。它们被用作后续的实验。然后研究了这两种鼠李糖脂对正十六烷的增溶作用,以及单糖脂的吸附作用对铜绿假单胞菌降解葡萄糖、高浓度鼠李糖脂单糖脂胶团化正十六烷以及单独相正十六烷的影响。实验结果表明,在浓度低于CMC和高于CMC时鼠李糖脂单糖脂对正十六烷的摩尔增溶比不同,而在整个浓度范围内二糖脂对正十六烷的摩尔增溶比不变。低浓度单糖脂的吸附抑制了菌体对葡萄糖和单独相正十六烷的降解,而高浓度单糖脂的吸附未影响菌体对葡萄糖的降解,但却促进了其对单独相正十六烷的降解。在实验时间范围内,吸附和未吸附单糖脂的菌体均不能降解高浓度的单糖脂胶团化的正十六烷,这表明该铜绿假单胞菌不能利用此胶团中的正十六烷。最后研究Triton X-100、二鼠李糖脂(di-RL)和CTAB等三种表面活性剂对一株热带假丝酵母降解十六烷的影响。结果表明,表面活性剂的类型和浓度均影响菌的生长及其十六烷的降解。低浓度的TX-100对菌的生长及其十六烷的降解影响较小,而高浓度的TX-100则抑制菌的生长及其十六烷的降解。di-RL促进菌的生长及其十六烷的降解,且促进作用随着di-RL浓度的增加而增大；di-RL在发酵过程中被降解,且添加的di-RL的浓度越大其被降解的比例越大。CTAB对热带假丝酵母具有毒性作用。本论文揭示了生物表面活性剂鼠李糖脂的微生物吸附规律,并证实了它有改变菌体表面亲水疏水性的作用。因为在很低的表面活性剂浓度下该作用就能发生,所以增加了将生物表面活性剂经济有效地应用于土壤修复中的可能性,特别是添加外源菌种的原位修复的可能性。更多还原

【Abstract】 In soil remediation, one way of biosurfactants enhance degradation of hydrophobic organic contaminants is to increase the surface hydrophobicity of microbial cell and facilitate the direct contact of microorganisms with the contaminants trapped in soil pores. However, the manner of interaction between biosurfactants and microorganisms as well as the rules of cell surface hydrophobicity change as the function of biosurfactants were not fully understood. In this paper, the effects of different kinds surfactants on degradation of different carbon sources are systematically studied.First the rhamnolipid biosurfactant was produced by aerobic fermentation using a Pseudomonas aeruginosa strain. It was separated from the culture by acid precipitation and purified by column chromatography until monorhamnolipid and dirhamnolipid were obtained. HPLC-MS examination showed that both of the rhamnolipids contained three main components and they were used in the following studies.Then the ability of the two rhamonolipid to enhance the apparent solubility of n-hexadecane was investigated, and the effect of monorhamnolipid adsorption on degradation of glucose, aggregate-incorporated n-hexadecane and single-phased n-hexadecane was also studied. The monorhamnolipid exhibited different manner of enhancing hexadecane solubility when its aqueous concentration was lower or higher than CMC, while the capability of dirhamnolipid was the same in the whole concentration range tested. Adsorption of monorhamnolipid of low concentration to some extent restricted the cell growth on glucose and single-pahsed hexadecane, however, adsorption of monorhamnolipid of high concentration had insignificant or stimulative effect on the cell growth on glucose and on hexadecane, respectively. For the hexadecane incorporated in aggregates formed by high-concentration monorhamnolipid, they could not be degraded by the cells treated with or without the surfactant. This result indicated that the incorporated hexadecane was unavailable to the Pseudomonas aeruginosa strain.Finally the effects of three kinds of surfactans (Triton X-100,di-RL,CTAB) on hexadecane degradation by Candida tropicalis CICC 1463 were studied. Results showed that both type and concentration of the surfactants affected cell growth and hexadecane degradation. The cell growth and hexadecane degradation were little effected by TX-100 of low concentrations, but inhibited at high concentrations. Di-RL increasingly enhanced cell growth and hexadecane degradation with concentration increasing. Di-RL was also degraded in the fermentation process, and the degradation rate increased with concentration increasing. CTAB was toxic to Candida tropicalis CICC 1463.The paper disclosed the effect of adsorption of rhamnolipid biosurfactants to microorganisms changing cell surface hydrophobicity. Because this effect occurs at low biosurfactant concentrations, it implies the possibility of economical and effective application of biosurfactant in soil remediation, especially in situ remediation with exogenous bacterial amendments.更多还原