生物表面活性剂公开课一等奖市赛课获奖课件.pptx

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,Biosurfactant,姓名：吕梅玲,学号：,SY1227111,化学与环境学院,导师：江雷,Introduction,Biosurfactants(,amphiphilic compounds,),(synthesized by microorganisms),hydrophobic,(nonpolar),hydrophilic,(polar),that confer ability to accumulate between fluid phases such as oil/water or air/water,reducing the surface and interfacial tensions and forming emulsions.,household、industry and agriculture,mono-,oligo-or polysaccharides(多糖）,peptides（缩氨酸）or proteins,saturated,unsaturated and hydroxylated fatty acids or fatty alcohols,Pseudomonas aeruginosa,（绿脓假单胞菌）,Acinetobacter calcoaceticus,（醋酸钙不动杆菌）,emulsan（乳化剂）,Candida bombicola,（假丝酵母菌）,sophorolipids（槐糖脂）,(Originally),hydrocarbons dissolution agents,food,pharmaceutical and oil industry,(recently),application,environmental friendly,easily biodegradable,low toxicity,unique structures,Rhamnolipids(,鼠李糖脂）,.Classification,Biosurfactants are categorized by their,chemical composition,molecular weight,physico-chemical properties,and,mode of action,and,microbial origin,.Based on molecular weight they are divided into,low-molecular-mass biosurfactants,and into,high-molecular-mass biosurfactants.,One of the best-studied glycolipids is,rhamnolipid,produced by several species of,P.seudomonads,（假单胞菌）,which consists of two moles of rhamnose and two moles of-hydroxydecanoic acid.,The,low molecular,weight biosurfactants are generally glycolipids in which carbohydrates are attached to a,long-chain aliphatic acid(脂肪酸）or lipopeptides（脂肽）,.,Glycolipid bioemulsifiers,such as rhamnolipids（鼠李糖脂）,trehaloselipids（海藻糖脂）and sophorolipids（槐糖脂）,are disaccharides（二糖）that are acylated with long-chain fatty acids or hydroxy fatty acids.,The high molecular weight surfactants are less effective in reducing interfacial tension,but are efficient at coating the oil droplets and preventing their coalescence,.These are highly efficient emulsifiers that work at low concentrations(0.01%0.001%),representing emulsifier-to-hydrocarbon ratios of 1:1001:1000.,The,high molecular weight bacterial surfactants,are,produced by a large number of bacterial species from different genera and are composed of polysaccharides（多糖）,proteins,lipopolysaccharides（脂多糖）,lipoproteins（脂蛋白）or complex mixtures of these biopolymers.,others can also emulsify pure hydrocarbons but only of a high molecular weight.The best-studied biosurfactants are the bioemulsans produced by different species of,Acinetobacter,.,These high molecular weight bioemulsifiers,exhibit considerable substrate specificity,.,For example,some emulsify efficiently mixtures of aliphatic and aromatic (or cyclic alkane)hydrocarbons,but will not emulsify pure aliphatic,aromatic or cyclic hydrocarbons;,Based on the microbial origin,the major class of biosurfactant include:,Glycolipids(糖脂）,Rhamnolipids（鼠李糖脂）,Trehalolipids(海藻糖脂）,Sophorolipids（槐糖脂）,Lipopeptide and Lipoprotein（脂肽和脂蛋白）,Fatty Acids,Phospholipids（磷脂质),and Neutral Lipids,Polymeric Biosurfactants,Particulate Biosurfactant,Properties,Surface and interface activity,biodegradability(,bioremediation,),.,emulsifying,and demulsifying ability,antimicrobial activity,Surface and interface activity,In general,biosurfactants are more effective and efficient and their,CMC,(critical micelle concentration)is about 10-40 times lower than chemical surfactants,i.e.,less surfactant is necessary to get a maximal decrease on ST.,A good surfactant can lower surface tension(ST)of water from,72 to 35,mN/m and the interfacial tension(IT)water/hexadecane（十六烷）from 40 to 1 mN/m.,The biosurfactants,accumulate at the interface between two immiscible fluids or between a fluid and a solid.,.(,figure 1,),By reducing surface(liquid-air)and interfacial(liquid-liquid)tension they reduce the repulsive f,orces between two dissimilar phases and allow these two phases to mix and interact more easily,Biosurfactant activities depend on the concentration of the surface-active compounds until the,critical micelle,concentration(CMC),is obtained.At concentrations above the CMC,biosurfactant molecules associate to form micelles,bilayers and vesicles(,Figure 2,).,The CMC is commonly used to measure the,efficiency,of surfactant.Efficient biosurfactants have a low CMC,which means that less biosurfactant is required to decrease the surface tension.,The biosurfactant,effectiveness,is determined by measuring its ability to change surface and interfacial tensions,stabilization of emulsions and by studying its,hydrophilic-lipophilic balance(HLB).,Emulsifiers with low HLB are lipophilic and stabilize water-in-oil emulsification,whereas emulsifiers with high HLB have the opposite effect and confer better water solubility,Low toxicity,For example:A biosurfactant from,P.aeruginosa,（绿脓假单胞菌）,（was compared with a synthetic surfactant(Marlon A-350)widely used in industry in terms of toxicity and mutagenic properties.Both assays indicated the higher toxicity and mutagenic effect of the chemical-derived surfactant whereas biosurfactant was considered slightly to non-toxic and non-mutagenic.,low or non-toxic products,and therefore,appropriate for,pharmaceutical,cosmetic and food uses,.,Emulsion forming and emulsion breaking,An emulsion is a,heterogeneous system,consisting of at least one immiscible liquid intimately dispersed in another in the form of droplets,whose diameter in general exceeds 0.1 m.Emulsions have an internal or dispersed and an external or continuous phase,so there are generally two types:,oil-in-water(o/w),or,water-in-oil(w/o)emulsions,.,Such systems possess a minimal stability,which may be accentuated by additives such as surface-active agents(surfactants).Thus,stable emulsions can be produced with a life span of months and years.Biosurfactants may stabilize(,emulsifiers,)or destabilize(,de-emulsifiers,)the emulsion.High-molecular-mass biosurfactants are in general better emulsifiers than low-molecular-mass biosurfactants.,Antimicrobial activity,A significative reduction on the mycoflora（真菌群）present in stored grains of corn,peanuts and cottonseeds was observed at iturin concentration of 50-100 ppm).Inactivation of enveloped virus such as herpes（疱疹）and retrovirus（逆转录酶病毒）was observed with 80 m M of surfactin（脂肽）.,Several biosurfactants have shown antimicrobial action against,bacteria,fungi（真菌）,algae（藻类）and viruses.,The lipopeptide iturin（脂肽伊枯草菌素）from,B.subtilis,（枯草芽孢杆菌）showed potent antifungal activity.,Production,Biosurfactants do not compete economically with synthetic surfactants.To reduce production costs,other carbon sources,such as,olive oil（橄榄油），mill effluent（工厂废水）,whey（乳清）,from cheese making,and,cassava flour water（木薯粉水）,used vegetable oils,molasses（糖浆）(by-product).,Biosurfactants have been synthesized by various researchers,using different microorganisms and carbon sources,.The carbon sources used for biosurfactant production are,hydrocarbons,carbohydrates,and,vegetable oils,.,Production methods,Natural biological extract method、Microorganism fermentation method、Enzyme catalytic method,Purification methods,Precipitation method、Extraction method、Superfiltering method、Foam separation method、Adsorption method、Column chromatography method、Thin layer chromatography method、,High performance liquid chromatography method、Liquid surface adsorption enrichment method、Liquid membrane separation method.,Fig.2.Structure of four different rhamnolipids produced by,P.aeruginosa,.,Factors Affecting Biosurfactant Production,Effect of Carbon Source on Biosurfactants Production,carbohydrate,hydrocarbon,vegetable oils,Effect of Support Material and Relationship with Water,Support material for immobilized enzyme affects the water content,in the proximity of the enzyme and the partitioning of reactants and/or products in the reaction mixture.Since thermal stability is closely related to the amount of water in close vicinity of the enzymes molecule.The ideal carrier should not retain water than necessary to reduce the risk of enzyme denaturation（变性）.,Immobilization on hydrophilic supports,often leads to a loss of lipase（脂肪酶）activity as the enzyme undergoes a conformational（构象）change to a form of reduced activity.These support materials may also reduce hydrophobic substrate solubility in hydrophilic regions,thereby reducing the accessibility of substrate to the active sites.,Effect of Environmental Factors on Biosurfactants Production,pH,temperature,agitation（搅拌）speed,oxygen availability,Rhamnolipid production,in,pseudomonas sp,（假单胞菌）was,its maximum at a pH range from 6 to 6.5,and decreased sharply above pH 7.,In addition,surface tension and CMCs,of a biosurfactant product remained stable over a,wide range,of pH values,whereas,emulsification,had a,narrower pH range,.,A thermophilic,Bacillus sp,（芽孢杆菌）grew and produced biosurfactant,at temperature above 40,.Heat treatment of some biosurfactants caused no appreciable change in biosurfactant properties,such as the lowering of the surface tension and interfacial tension and the emulsification efficiency,all of that remained stable after autoclaving（高压灭菌）at 120,for 15 min.,An increase in agitation speed,result in the reduction of biosurfactant yield due to the effect of shear in,Nocardia,（土壤丝菌属）.On other hand,in yeast,biosurfactant production increases when the agitation and aeration rates are increased.,Salt concentration,also affected biosurfactant production depending on its effects on cellular activity.Some biosurfactant products,however,were not affected by salt concentrations up to 10%(wt/vol),although slight reduction in the CMCs were detected.,a modified drop-collapse technique for surfactant quantitation and screening of biosurfactant producing microorganisms,Qualitative drop-collapse test,A drop of water applied to,a hydrophobic surface in the absence of surfactants,will form a bead,as shown in,Fig.1(A).,The bead forms,because the polar water molecules are repelled from the hydrophobic surface.,In contrast,if the water droplet contains surfactant,the force or interfacial tension between the water drop and the hydrophobic surface is reduced,which results in the spreading of the water drop over the hydrophobic surface(,Fig.1,B,).The amount of surfactant required to cause drop-collapse is dependent on the ability of the surfactant to reduce surface and interfacial tension.The more potent the surfactant,the smaller the quantity that can be detected.,(A)Water control(no surfactant),(B)1000 mg/L rhamnolipid.,surfactant quantitation by the drop-collapse,Quantitative drop-collapse method:,(A),Water control,(B),25 mg/L rhamnolipid,(C),50 mg/L rhamnolipid,(D),75 mg/L rhamnolipid and,(E),100 mg/L rhamnolipid.,In this case,as the surfactant concentration increased,the diameter of the sample drop increased.,Quantitative results for two surfactants,rhamnolipid and SDS,are presented as standard curves in,Fig.2.,A linear correlation was found between the rhamnolipid concentration and the drop diameter,in the range of 0 to 100 mg/L,with an r,2,=of 0.997,(Fig.2A).,For SDS,(Fig.2B),concentrations between 0 and 2400 mg/L were linearly correlated with drop diameter(r,2,=50.989).,Fig.2.The quantitative drop-collapse method.The figure shows the results obtained with two different surfactants:,(A),P.aeruginosa IGB83 with a CMC of 27 mg/L and,(B),SDS with a CMC of 1845 mg/L.Each point represents the mean and standard deviation of five replicates from experiments that were carried out in triplicate.,Potential Commercial Applications,Most surfactants are chemically synthesized.Nevertheless,in recent years,much attention has been directed toward,biosurfactants due to their broad-range functional properties and the diverse synthetic capabilities of microbes,.Most important is their,environmental acceptability,because they are readily biodegradable and have lower toxicity than synthetic surfactants.A number of applications of biosurfactants have been envisaged.,MEOR,、Food Industry、Cosmetic Industry、Medicinal Use、,Soil Bioremediation,Biosurfactants in Microbial Enhanced Oil Recovery(MEOR),Fig.Mechanism of enhanced oil recovery by biosurfactants.,the oil is trapped in the pores by capillary pressure.,Biosurfactants reduce interfacial tension between oil/water and oil/rock.This reduces the capillary forces preventing oil from moving through rock pores.,Biosurfactants can also bind tightly to the oil-water interface and form emulsion.This stabilizes the desorbed oil in water and allows removal of oil along with the injection water.,The Application of Biosurfactants for Soil Bioremediation,The biological remediation process can be performed,(i)in situ,(ii)in a prepared bed,(,iii)in a slurry reactor system,In situ processes are usually accomplished by addition of microbial nutrients to the soil,which allows considerable growth of soil microbial indigenous population.Thus increased microbial biomass in the soil.(fig1),Figure 3,Mechanism of biosurfactant activity in metal-contaminated soil,due to the lowering of the interfacial tension.,Conclusion,Advantage:,higher biodegradability,better environmental compatibility,higher foaming,high selectivity and high specific activity at extreme temperature,pH and salinity,.,There the demand of biosurfactants is increasing worldwide in recent years.,However,biosurfactants do not economically compete with chemically synthesized surfactants.Thats why there is a great scope for further research to find a more economical production process and technology.,Thank You,