InoculationconcentrationmodulatingthesecretionandaccumulationpatternofexopolysaccharidesindesertcyanobacteriumMicrocoleusvaginatusLongQian1LiWu1∗LieYang1∗ZulinZhang1,2∗1SchoolofResourcesandEnvironmentalEngineering,WuhanUniversityofTechnology,Wuhan,People’sRepublicofChina2TheJamesHuttonInstitute,Craigiebuckler,Aberdeen,UKAbstractCyanobacterialexopolysaccharides(EPS)accumulatedduringmicroalgalcultivationhavesignificantapplicationpotentialinantioxidation,pharmaceuticalproducts,andsoon.Inoculationconcentrationstronglyaffectsthecultivationcost,biomass,andEPSaccumulation.Inthisstudy,ahigh-EPS-excreteddesertcyanobacteriumMicrocoleusvaginatuswasisolated,andtheeffectsofinoculationconcentrationonbiomass,photosyntheticactivity,andEPSaccumulationwereexplored.Theresultsshowedthattheoriginalfluorescence(Fo)providedagoodindicationtocyanobacterialbiomass,whenChl-aconcentrationwaslowerthan10mgL−1.InoculationconcentrationsignificantlyaffectedcyanobacterialbiomassandEPSconcentration(P<0.001),whereasdidnotaffectphotosyntheticactivity(Fv/Fm;P>0.05).ThetwofractionsofEPS,capsularexopolysaccharides(CPS)andreleasedexopolysaccharides(RPS)werestronglyaffectbyinoculationconcentration.Otherthanformingthicksheath(CPS)surroundedthefilaments,M.vaginatusexcretedhigherproportionsofRPStoculturemedium,andtheratioofRPStoCPSrangedfrom1.08to1.58dependingontheinoculationconcentration.Additionally,althoughthebiomassandEPSaccumulationincreasedwithinoculationconcentration,theincreasinginoculationconcentrationdidnotbringtotheproportionateincreaseofthefinalbiomassandEPSyield.Altogether,comprehensivelyconsideringtheEPSyieldandproductivity,inoculationconcentrationof0.04mgChl-aL−1isrecommendedforM.vaginatustoproduceEPS,withanEPSyieldof94.32mgL−1andEPSproductivityof184.86mg(mgChl-a)−1L−1d−1attheendofexperiment.©2020InternationalUnionofBiochemistryandMolecularBiology,Inc.Volume68,Number2,Pages330–337,2021Keywords:microalgae,biomass,exopolysaccharides,desert,crust1.IntroductionAsresourceandenvironment...
