AntonievanLeeuwenhoek(2007)91:1–17DOI10.1007/s10482-006-9095-5REVIEWARTICLEPolyhydroxyalkanoatesinGram-positivebacteria:insightsfromthegeneraBacillusandStreptomycesSabeelP.ValappilÆAldoR.BoccacciniÆChristopherBuckeÆIpsitaRoyReceived:27March2006/Accepted:23May2006/Publishedonline:3October2006ÓSpringerScience+BusinessMediaB.V.2006AbstractGram-positivebacteria,notablyBacillusKeywordsBacillusÆGram-positivebacteriaÆandStreptomyces,havebeenusedextensivelyinPolyhydroxyalkanoateÆLipopolysaccharideÆindustry.However,thesemicroorganismshavePoly-3-hydroxybutyrateÆStreptomycesnotyetbeenexploitedfortheproductionofthebiodegradablepolymers,polyhydroxyalkanoatesAbbreviations(PHAs).AlthoughPHAshavemanypotentialdcwdrycellweightapplications,thecostofproductionmeansthatHBhydroxybutyratemedicalapplicationsarecurrentlythemainareaHHphydroxyheptanoateofuse.Gram-negativebacteria,currentlytheonlyHHxhydroxyhexanoatecommercialsourceofPHAs,havelipopolysac-HOhydroxyoctanoatecharides(LPS)whichco-purifywiththePHAsHPhydroxypyvalicacidandcauseimmunogenicreactions.OntheotherHVhydroxyvaleratehand,Gram-positivebacterialackLPS,apositiveLPSlipopolysaccharidefeaturewhichjustifiesintensiveinvestigationintomclmediumchainlengththeirproductionofPHAs.Thisreviewsumma-PHAPolyhydroxyalkanoaterizescurrentlyavailableknowledgeonPHAphaAgeneencodingb-ketothiolaseproductionbyGram-positivebacteriaespeciallyphaBgeneencodingacetoacetyl-CoAreductaseBacillusandStreptomyces.WehopethatthiswillphaCgeneencodingPHAsynthaseformthebasisoffurtherresearchintodevelopingphaRgeneencodingasubunitofthePHAeitherorbothasasourceofPHAsformedicalsynthaseapplications.ROSreactiveoxygenspeciessclshortchainlengthSODsuperoxidedismutaseS.P.ValappilÆC.BuckeÆI.Roy(&)DepartmentofMolecularandAppliedBiosciences,SchoolofBiosciences,UniversityofWestminster,115NewCavendishStreet,LondonW1W6UW,UKe-mail:royi@wmin.ac.ukIntroductionA.R.BoccacciniÆS.P.ValappilDepartmentofMaterials,ImperialCollegeLondon,Polyhydroxyalkan