生物表面活性剂及其在环境修复中的研究进展

生物表面活性剂是由微生物分泌的天然产物,由于其物理性质和化学结构与许多人工合成的表面活性剂相似,并且对土壤、淡水、海洋等生态系统毒性较低,因而在环境污染治理方面,特别是在重金属和石油等有机溶剂污染的原位和异位生物修复方面具有极大的应用潜力.主要综述了近年国内外生物表面活性剂在廉价制备、作用机理、环境修复中的研究进展.     

拟威克酵母产生表面活性剂的发酵条件

通过单因子试验和正交试验,对拟威克酵母WickerhamielladomercqiaeY2A产生槐糖脂的发酵培养基组成和发酵条件进行了优化.培养基组成为:8.0%葡萄糖、8.0%菜子油、0.3%酵母粉;发酵条件为:初始pH值6.0、接种量2.5%、发酵时间120h.在此条件下,槐糖脂产量可达到41.3gL-1.图4表5参16     

鼠李糖脂对东海典型甲藻赤潮生物生长抑制作用的影响

探讨了铜绿假单胞菌产鼠李糖脂类生物表面活性剂对东海典型甲藻赤潮生物锥状斯式藻(Scrippsiella trochoidea)、塔玛亚历山大藻(Alexandrium tamarense)、海洋原甲藻(Prococentrum marinum)和微小原甲藻(P.minium)生长的抑制作用,并对其不同抑制作用的机理进行了初步探讨.结果表明,鼠李糖脂在一定浓度范围内对几种甲藻的生长表现出明显的抑制作用,对几种甲藻生长抑制作用的强弱顺序为:锥状斯式藻>微小原甲藻>塔玛亚历山大藻>海洋原甲藻.对不同属的甲藻,这种抑制作用可能与藻细胞本身表面的附属物、内部物质组成及个体大小有关;而对于同一属的甲藻则与各甲藻的生物膜脂肪酸组成尤其是其多不饱和脂肪酸的含量有关,即甲藻的多不饱和脂肪酸含量越低,鼠李糖脂对藻细胞生长的抑制作用越明显,反之亦然.图1表2参18     

鼠李糖脂对沉积物中Cd和Pb的去除作用

用铜绿假单胞菌(Pseudomonas aeruginosa)产生的鼠李糖脂生物表面活性剂对沉积物中重金属的去除作用进行了研究．研究表明,鼠李糖脂对沉积物中的Cd和Pb有明显的去除作用,在鼠李糖脂溶液的pH值为10．0的条件下对重金属的去除效率最好,而且当鼠李糖脂在沉积物上的吸附达到饱和时去除效率达到最大．通过连续萃取对提取前和提取后沉积物样品中重金属的形态进行分析,发现可交换态和有机结合态的重金属较容易去除．通过4次连续的提取,使cd和Pb的去除效率分别达到80．1％和36．5％．     

生物表面活性剂对东海原甲藻生长的影响

以东海原甲藻为实验材料,研究了铜绿假单胞菌产鼠李糖脂类生物表面活性剂对藻细胞的抑制和杀藻作用.结果表明,鼠李糖脂在较低浓度下对东海原甲藻的生长有明显的抑制效果,增大用量,可直接杀灭藻细胞.生长延滞期的藻细胞对鼠李糖脂的作用更为敏感.在相同实验条件下,鼠李糖脂对绿藻生长的影响基本可以忽略,在低浓度下对中肋骨条藻和湛江叉鞭金藻生长的影响也很弱,鼠李糖脂的浓度增至5.0mg/L 以上时,对中肋骨条藻和湛江叉鞭金藻的生长表现出一定的抑制作用.     

Comparative degradation between heavy and light crude oil mediated by nitrogen‐induced cell‐surface hydrophobicity

A bacterial strain UKMP‐10M2 isolated from a Malaysian petroleum refinery was able to degrade 84% of heavy Khafji sour crude and 68% of light Tapis sweet crude within seven days. Analysis of gas chromatography‐flame ionization detector chromatograms show the strain UKMP‐10M2 degraded up to 90% pristane and 50% phytane in heavy crude, but significantly lower pristane (50%) and phytane (30%) were degraded from the light crude. A mixture of aliphatic hexadecane and three‐ring phenanthrene better supported the growth of isolate UKMP‐10M2 compared to using phenanthrene alone, suggesting cometabolism influenced how crude oil with different individual hydrocarbon contents affected the degradation. Peptone as the source of nitrogen increases the emulsifying index in UKMP‐10M2 exposed to heavy Khafji sour crude 20% higher than in light Tapis sweet crude. However, BATH assay showed the same nitrogen source increases bacterial cell surface hydrophobicity of UKMP‐10M2 up to 14% higher in light Tapis crude oil compared to heavy Khafji. This study suggest the nitrogen source plays a decisive role in elevating UKMP‐10M2 bacterial cells hydrophobicity, and in correlation with types of crude oil. Phylogenetic tree analysis based on 16S rDNA sequence results identified the strain to be Rhodococcus ruber.     

基于生物表面活性剂的柴油微乳体系构建与性能研究

以生物表面活性剂鼠李糖脂（RL）为表面活性剂，中长碳链正构醇（正丁醇、正戊醇、正己醇、正庚醇及正辛醇）为助表面活性剂，采用滴定法制备RL／柴油／正构醇／水柴油微乳体系，并考察了表面活性剂用量（Km）、助表面活性剂醇的种类及用量（δas）及离子强度对柴油微乳体系最大增溶水量（Wo）的影响，并对不同条件下获得的柴油微乳体系的运动粘度（μ）和表面张力（γ）进行了表征。通过荧光法测得RL在柴油中的临界胶束浓度CMC为7g／L。当生物表面活性剂与柴油的质量比Km为0．02，助表面活性剂选用正庚醇且醇与表面活性剂的质量比δgs为0．1，NaOH溶液质量分数为0．06％时，柴油微乳体系的肛和T较低，形。最大，性能较佳。     

Influence of biosurfactant on the diesel oil remediation in soil-water system

There were six high diesel oil degrading bacteria strains isolated from the oil contaminated soil that collected from Linzi City. The strain YI was able to produce biosurfactant rhanmolipid when cultivated on diesel oil as carbon source. The critical micelle concentrations （CMC） of rhanmolipid in water and in the soil were measured respectively according to the correlation between the surface tension of the medium and the added rhamnolipid concentration. The results showed that the CMC of rhanmolipid in water was 65 mg/L, and was 185 mg/L in soil. The tests on diesel oil biodegradation were conducted with the addition of different concentrations of rhamnolipid in water and in soil respectively. When 0.01% rhanmolipid was added to water, the diesel oil degradation was enhanced. On the contrary, when the same concentration of rhanmolipid was added to the soil, the degradation of diesel oil was inhibited. The results suggested that the rhamnolipid could enhance the diesel oil biodegradation, indicating that the concentration of rhamnolipid was higher than the corresponding CMC in the medium. Kinetics parameters for the diesel oil biodegradation parameters such as biodegradation constant （λ）, coefficient of correlation （r） and half life （t1/2） in both tests were numerically analyzed in this paper, indicating that the moderate concentration of rhamnolipid in the medium could not only enhance the extent of diesel oil biodegradation but also shorten the time for oil remediation.     

生物表面活性剂的优化生产及发展前景

生物表面活性剂(Bio-surfactant)是由微生物产生的具有高表面活性的生物分子。由于其对生态系统无毒害作用,且可生物降解,因此,在提高原油产收率和环境污染治理等各方面得到了广泛应用。然而能否大幅度提高生物表面活性剂发酵产量是其能否实现商业化的一个首要问题。为此文章纵观了目前提高产量的研究重点,并对应用诱变育种和构建基因工程菌手段提高产量的发展前景作了展望。