Synthesis Of Sugar Ester Catalyzed By CALB Displaying Pichia Pastoris In Large-scale

Sugar fatty acid esters are a group of significant nonionic surfactants which are a class oforganic compounds synthesized of sugar with fatty acid. They are non-toxic, odorless, no-skinirritants, completely biodegradable under aerobic and anaerobic conditions and a wide rangeof HLB value (1-16), they also can be dispersed lubrication, emulsification, foaming,viscosity adjustment, against aging, preventing crystallization and, antimicrobial. They havebroad applications and good development in food, daily chemical, pharmaceutical and otherindustries. Many Scholars give enough concern on them due to their surfactant properties andenvironment-friendly advantages.At present, although there are many studies dealing with lipase-catalyzed synthesis ofvarious kinds of sugar esters in organic solvents, their industrialization has not yet beenrealized. High cost of lipase and the use of toxic solvents (DMSO, DMF, pyridine) lead tohard to purification, also it limits its application in the food and medicine. There is still a gapfar from the industrialized production requirements for the low conversion. In this paper, therecombinant CALB displayed on Pichia pastoriswas used as a whole-cell biocatalyst tosynthesis of sugar ester in the organic phase. Compared with immobilized enzymes,enzyme-displaying yeast biocatalyst seems to be an alternative due to its simplicity, highenzymatic activity and cost-effective as well. So it has a wide prospect. This topic focuses onthe proceed from reducing the use of toxic solvents and the methods of substrate modificationis just to improve the conversion, we also can enlarge its scale. So that we can provide thenecessary information for designing the reactor and continuous to synthesis of sugar ester.We can use a less polar sugar derivative as a hydroxyl donor instead of an unmodifiedsugar to overcome the low solubility of sugars in an organic solvent. Using1,2-O-isopropylidene-α-D-glucofuranose (IpGlc) as the acyl acceptor,lauric as the acyldonor in the reaction system, we will optimization of reaction conditions on the recombinantCALB displayed on the surface of Pichia pastoris to synthesis of sugar acetals esters, such assolvent, catalyst dosage, the type of enzyme, substrate molar ratio,4molecular sievedosage, water activity and temperature. The optimal reaction conditions is: IpGlc0.5mmol,lauric2.5mmol, GS115/GCW21-42-CALB0.3g,4molecular sieves0g,aw=0.11,5mLacetone,50°C,200rpm,60h. The conversion of IpGlc-C12could be90%, while it could be89.79%when using Novozyme435.If using the glucose as a substrate, the conversion rate is25.46%. The alkyl glycoside is also a good substratefor it is a surfactant, and then the product ofsugar ester synthesis do not need to be deprotected. Such compounds can be used as excellentemulsifiers, emollients and thickeners, They are also widely used in the cosmetics industry.Such compounds are important drug candidates. We use different chain lengths glycosides asa substrate to synthesis sugar esters, we will get the maximum conversion when using methylglucoside. Using methyl glucoside as the acyl acceptor, lauric as the acyl doner in the reactionsystem, The optimal reaction conditions were: methyl glucoside0.5mmol, lauric1.5mmol,GS115/GCW21-42-CALB0.2g,4molecular sieves0.2g, aw=0.06,5mL acetonitrile,50°C,200rpm,72h. The conversion of methyl glucoside laurate ester could be89.2%.As the property of glucose myristate is similar to glucose laurate. In this study, wesynthesisof IpGlc-C14in2L/5L batch stirred reactor. The important factor in the impact oflarge-scale reaction-water control, it is mainly from the outside of the reaction system (theadded amount of4molecular sieves) and lipase water content (drying temperature ofGS115/GCW21-42-CALB). The optimal reaction conditions were:40g/L4molecularsieves, drying temperature of GS115/GCW21-42-CALB95°C. To further examine thepotential of the biocatalyst for sugar esters synthesis,the operational stability of GS115/GCW21-42-CALB in organic solvents was investigated. Theresults indicated that: theconversion of IpGlc-C14remained80.30%(8batch) and85.35%(5batch) of the first batch.We study on different conditions (trifluoroacetic acid, formic acid, hydrochloric acid, glacialacetic acid) to deprotected. When using70%trifluoroacetic acid to deprotected IpGlc-C14,glucose myristate can achieve95.63%.