Springer.Advances.in.Biochemical.Engineering.Biotechnology.Biopolyesters

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1、PrefaceLivingsystemssynthesizesevenclassesofpolymers.Someofthem,forinstancewaterinsolublepolyesters,havebecomecommerciallyattractive.Waterinso-lublepolyestersaresynthesizedbyawiderangeofdifferentprokaryoticmicro-organismsincludingeubacteriaandarchaeamostly

2、asintracellularstoragecompoundsforenergyandcarbon.Theyrepresentarathercomplexclasscon-sistingofalargenumberofdifferenthydroxyalkanoicacidsandaregenerallyreferredtoaspolyhydroxyalkanoates(PHA).Waterinsolublepolyestersarealsosynthesizedbyplantsasstructuralco

3、mponentsofthecuticlethatcoverstheaerialpartsofplants.Eukaryoticmicroorganismsandanimalsarenotcapableofsynthesizingwaterinsolublepolyesters;onlysomeeukaryoticmicroorga-nismshavebeenknownwhichcansynthesizethewatersolublepolyesterpoly-malicacid.Thewaterinsolu

4、blepolyesterspossessinterestingproperties.Theyarebiode-gradableandbiocompatibleandexhibitphysicalandmaterialpropertiesmakingthemsuitableforvarioustechnicalapplicationsinindustry,agriculture,medicine,pharmacyandsomeotherareas.Themicrobialpolyesterscanbeprod

5、ucedeasilybymeansofwell-knownfermentationprocessesfromrene-wableandfossilresourcesandevenfrompotentiallytoxicwasteproducts.How-ever,thepriceofPHAsisratherhighcomparedwithconventionalsyntheticpolymers.Ifwewanttousethesebiopolymers,itisnecessarytoimprovethee

6、conomicviabilityofproductionprocess.Therefore,alotofresearchworkhasbeendone.Duringthelastdecadesignificantprogresshasbeenmadeineluci-datingthephysiological,biochemicalandgeneticbasisforthebiosynthesisandbiodegradationofthesepolyestersandalsoindevelopingeff

7、ectiveprocessregimes.Novelapplicationshavebeenfound.Thesynthesisandintracellularaswellasextracellulardepolymerizationofthesepolyestersarenowunderstoodquitewell.Thegenesencodingtheenzymesofthepathwaysorstructuralpro-teinsattachedtothePHAgranulesinbacteriaha

8、vebeenclonedandcharacter-izedfrommanybacteria.TheavailabilityofthisknowledgehascontributedsignificantlytoestablishingnewprocessesfortheproductionofPHAsbymeansofrecombinantbacteriaandtotailoringthepropertiesof