An overview of Engineering Aspects of Solid State Fermentation.docx

马来西亚的微生物学杂志第1卷(2ROO5f,pp.10-16文献综述工程方面的概述固态发解PrabhakanA.1*,Krishn<iah,k.Janaun.j.和波诺，化学工程项目,学院的工程学和信恩技术，马来西亚沙巴高校,88999年亚底、沙巴、马来西亚。电子邮件:ChakriaPurns.edu.my文嫡同体基质栽培(SSC)或固态发解(SSF)被想象作为一个重要的生.沏转化技术改造自然的原料加工成种化学以及生化产M.这个过程包括固体施防发酵培育基微生物在缺乏自由流淌的水.城近的进展和共同关注SSF启用它进化作为个潜在的生物技术的选择传统的化学合成，社保基金正在胜利地利用生产粮食、麴料、的制剂、抗生素、动物饲料和染料降解。本文论述了各种宏观和微观层面工程存在的问题和一些可能的解决方案SSF其全部商业实现.关键词:固态发酵、基材、扩放系数、养分、下海、传质、传热。介绍现代化学合成旨在三Es.能源、经济和环境.任何新的化学产品今日肯定是由最低能量的需求在Ai佳的成本为W的环境污染.作为生化过程是环境友好.成本效益和开展的环境条件下.满意约束的三个胚胎的生产各种化学和生化产品服芬于现代社会.Hcncc.biosyntheseshaveemergedasthepotentialalternativetotraditionalchemicalMaluysianJournalofMicrobiology.VblI(2)2005.pp.10-16REVIEWARTIC1.EAnoverviewofEngineeringAspectsofSolidStateFermentationPrabhakar.A.Krishn<iah.K.Janaun.J.andBono.A.ChemicalEngineeringProgram,SchoolofEngineeringandInformationTechnology,UniversitiMalaysiaSabalh88999KotaKinabalukSabahtMalaysia.Emciil:chakriapunis.edu.myAbstractSolidsubstHuecultivation(SSC)orsolidstatefermentation(SSF)isenvisionedasaPrOminCnlbioconventiontechniqueIotransformnatu11lrawmaterialsintoawidevarietyofchemicalaswellasbio-chemicalproducts.ThisprocessinvolvesthecrmcntationofsolidSubscratcmediumwithmicroorganismin(heabsenceoffreeowingwater.RcccnldevelopmentsalconcertedfocusonSSFenabledi(toevolveasaPOtenIialbiotechnologyas<nCilternalivetothetraditionalchemicalsynthesis.SSEisbeingsuccessfullyexploitedforfoodpr<iuction.fuels,enzymes,antibiotics,aninlfeedsandalsofordye(iegra<iaion.ThispaperdiscussesthevariousmicroandmacrolevelengineeringIMOblenISassociatedwithSSFandsomepossiblesolutionstorilsfullcommercialrealiilion.Keywords:Solid-statefcmcntation.substrate,diffusivity,nutrients,bio-rcactor.masstransfer,heattransfer.INrRODUeTIONMOdernchemicalsynthesisaimsatthreeEs.Energy.EconomyandEnvimnnient.Anynewchemicalproducttodaymustbeproducedwithminimumenergyrequirementatoxinvlcostwithzeroenvironnn(alpollution.Asthebic>-che11ivalprocessesareenvironmentfriendly,costeflectiveandcarriedoutatambientconditions,satisfytheaboveconstraintsofthreeEsfortheproductionofawidevarietyofchemicalandbiochemicalproductstoservethemodemsociety.-个是液态深层发冷(SmF)这是特别确定的,另一个是固态发酵(SSF).它仍在进化状态和在密集的探讨.有几个最近的出版物描述农业产业的固态发酵下脚料(如米楝、稻壳、马铃磐废物.木普皮,麦荻、甘蔗蔗渣、甜菜浆、棕桐仁蛋糕、稻草、可可0英.水果废弃物等进入大宗化工产品和增假的好产品.如乙醇、陆制剂、抗生素、生物燃料、的聒、有机酸、纵基酸、生物活性次生代蝌物(在1983年的探讨Moo-Young;多利在1992年的探讨:1998年,SoccolPimdey.Pandey在1999年的探讨500；0和V；IndCnhCrghC,W03;PrasCrKBn$;1996年,博阿斯等人,2002).最近,焦点被转换的自然废物变成动物、家禽和向炎膳食通过SSR博阿斯等人,2002;1998;1.eOnOWiCZNigam人.1999).原则上SSF指的是微生物的生长在潮湿的固体基质孔隙内或者与自由流滴的水.所前的水份,SSF存在于固体作为汲取或困难的表单更行利于氯微生物种群的可用性，在SSF微生物是在与大气中的氧与液态深层发解(SmF社保基金更简洁.须要更少的处理能源.基本区分SSF和SmF展示在友I、可以更好地理好-些SSF液程开发已经发表在了文学也展示在表2(Pandey和Soccol.1998).低含水率意味蓿发醉只Ife进行有限故里的微生物.主要酵母画和nI兄因此.因为较f氏的湿度变成或污染有否细用的降低.而更多的集中的产品生产.有评论的些方面的文献SSF，然而.本文探讨了工程何阳的概述强调生物反应器的设计与运行商业规模.该论文也强调了某些商业社保基金的应用.SSF工艺方法在仟何SSF工艺进行的基本步骤是：1.打算一个固体基质(dp、PH值、Cn.Cs).2。杀由的基质。3. Risingofsuitablei11(ulum.Traditionalorpureculturetechnique.4. ',hcinoculationofthemoistsubstratesyntheses.Therearetwotypesofb沁conversionmethodsinoperation,oneis(hesubmergedicmicntation(SmF)whichiswellestablishedandtheotherissolidstatefcmnta(ion(SSF)twhichisstillincvolutionarjs(mcandunderintensiveresearch.ThereareseveralrecentpublicationsdescribingIhcsolidstateIennenlaliunofag11>-indUSlriaIresiduessuchasrivebran,ricehusk,potatowastes,cassavahusk,wheatbran,sugarcancbagasse,sugarbeetpulp,palmkernelcake,ricestraw,cocoapod.fnitwastesetc.intohulkchemicalsandvalueaddedlineproductssuchasethanol,enzymes,antibiotics,biofuel,mushrooms,organicacidskaminoacidstbiologicallyac(ivesecondaryr11elat>lites(MOoYuungalU1.1983:DoeiICMal.1992:PandeyandSocco1.1998:Pandcyatal.1999:ScmzcoIandVandcnbcrghc.2(X)3:Prascrtsan,1996:Villas-Boasdal.2(XG).Morerecentlythefocushasbeen(heconventionofnaturalwastesintoanimal,poultryand11shmealsthroughSSF(Villas-Boase<al”2002;Nigam41998;1.eonowiczetal.1999).InprincipleSSFrcfen>tothemicrobialgrowthonmoistsolidsubstratesorwithin(beporeswithoutfreeIlowofwater.I*hcrequiredmoistureforSSFexistsinthesolidasabsorbedorcomplexf<x,nismorehelpfulforoxygenavailabilityto(hemicrobialPOIHIlaion.InSSF(hemicrobeisincontactwithatmosphericoxygenunlikeinsubneedIennentation(SmF).SSFissimplerandrequireslessPrCXxSSingenergy,l,hcbasicdiIYcrcnccsbetweenSSFandSmFarcpresentedinTable1forbelterundcrsrkiing.SomeoftheSSFprocessesdevelopedarcpublishedin(heliteraturearcalsopresentedinTable2(PandeyandSocco1.1998).Thelowmoisturecontentmeanslhatfernenta(ioncanonlybecarriedoutbyalimitednumberofmicrorganistns.mainlyyeastsandfungi,'bercfbrc.becauseoflowmoisturelevelsspoilageorcontaminationbyunwantedbacteriaisrcduccd,andInorCconcentratedproductisPrOdUCcd.Therehavebeenreviewsonson>eof(heaspectsofSSFintheliterature.However,thispaperdiscussesanoverviewOfthCengineeringproblemswithanemphasisonbireactordesignand<erationoncommercialscale.ThepaperalsohighlightsSOmeof(hecomnrcialapplicationsofSSESSFPRQeESSMETH()l)()1.(XiYInanySSFprocessthebasicstepscarriedoutarc:1. Thepreparationofasolidsubstrate(dp.pH,Cn,Cs).2. Sterilizationof(hesubstrate.因此,生物介成已成为潜在的替代传统的化学合成.有两种类型的转化方法在操作.这是生化反应速率的比值的扩散传项速率在固体.利用这一概念,可以开发一个标准来过怙iniraPanide质传热的限制来供应更大的洞察和叫!解到热质交换机制在SSF反应堆.米切尔等人（1<WO>,探讨/扩散的局限在凝胶基防SIUa>amy尿C转换到倒葫轴,其产以低至20%,因为他们没有考虑02的扩散和消侨intraparticle水平。米切尔等人（199OrRajagOpaIanetal（1995）,Moo-Young等人（198311H寸了扩敌限制不同翦质的总和,这阻碍了微生物的生氏速率和产品的收益率.在系统上运用强制通风、02转会不太可能速度限制,但：行些养分素转移可能会影响激生物的生长.在案件的tlamcntal真菌,层板取决干内部的粒子也转移和含水率粒子（杜兰他等人,998）才故的成在多数SSF处理能源和碳基随是大分子因此微生物不能运输高分子基体穿过细胞膜.所以行动在际解前的细胞外旭旗成可溶的固态碎片是一个特别1£要的一推.有时的'敢的反应堆UJ能SSF速率限制步骤（KnaPP和拿厄尔.1980）。因此exoenzymesUr能经验犷散和空间的限制取决于孔隙度的大分不结构（SUga等人,1975）.扩散的脚是由于开放的法质孔原几何,但当孔隙度施质降解的,与其说是发生在表面，所以.粒子大小、形态、孔隙度、一样性和实力是一些重要的参数中要考虑的工业冏体发酵,因为它In影响，采期的传热传质车和维护足修的水分在床上.（Suga等人J975:MitChdl等人.1988:ZadraZiI和PUniaJ995）.Howeverforo>innparticlesizeandstructuremodificationsbeforethefe11nentationareyettobefoundexperimentallythoughxetrea（nen（techniqueslikesteaming,puffing,extrusionetccanbeiap<ed（oenhancetheinterfucialareaandaccessibilityoftheevaluationoftheistheThCiIClnOdUIUB().whichistherat100fbiochemicalreactionrate(othatofdifusionalmasstransferratewithinthesolid.Bymakinguseof(hisconcept,acriterioncanbedeveloped(oCVaIuuleinlraparticlemassandheattransferIimilatiunstoprovidegreaterinsighlandunderstandingintothebeatandmasstransfermechanismsinSSFreactors.Mitchclctal.(1990),studied(he(IitYusionaIlimitationsofglucoamylascinagelsubstrate(oconvert(oglucose.ItsPrOdUCnonwasaslowas20%becausetheydidnotconsiderIhe02diffusionandconsumptionattheintraparticlclevel.Mitcheldal.,(199().Rajagopalanctal(1995),andMooYoungetal.,(1983)studiedtbcditYisionallimitationsonSSFofdifferentsubstrates,whichhirlcrcdthegrowthrateofmicroorganiMnsandproductyields.Insystemswithforcedaeration.02transferislesslikelytoberatelimiting,butsnenutrientstransfermightaffcc(thegrowthofthemicr()rganism.Intbccaseoffilanentalfungi,thelayeron(hesubs(,atedependsontheintraparticleoxygenUansferandthemoisturewntenlofthePdniCIe(DUnlnde<al.1998).DIFFUSIONOFENZYMESInmajorityofSSKprocessesthecarbonandenergysubstrateismacromolecularhcnccmicrrganismscanno<transo11nacronxlccularsubstrateacross<hccellnembnne.sotheactionofextracellularenzymesindegrading(hesolidstalesubstrateintosolublefragmentsisavcr,importantstep.SometimesenzymediffusionintheSSFreactorcouldbetheratecontrollingstep(KnappandHowell,1980).Thusexoenzymesmayexperience<Jifsionandstericlini(a(ionsdependingon(heporosityof(hemacromolecularstructure(Sugaelal.1975>.Thediffusionofenzy11>esiscausedbylheopenporegeometryofthesubstrate,butwhenthePomSityofsubstrateislessthedegradationoccursathcoutersurface.So,IhcParIiClCsize,shape,porosity,consistencyandstrengtharesomeof(heimor(anparameterstobeconsideredinindustrialsolidslatefe11nentationastheyaffectprofoundlythehealandmasstransferratesandmaintenanceofadequatemoistureintbcbed.(Sugactal.1975:Mitchcllctal.1988:ZadrazilandPuniaf1995).尽管它是用来量化在催化扩放限制也适用于SSF是UJ视化为个异构的系统,须要-个重要参数的评价是ThCilC模瓜().些大规模转移的探讨表明.强制循环中空气的床可以增加02转移和：班化碳耗散在床上假如流化床作为社保基金，热传导问题热代是成正比的代谢活动在SSF反应堆（吉哈尔,1983;罗宾逊和尼眼.2OO3）作为发群进展02扩放并触发bioreaCIionS用放出热也积累了在反应堆由于糟旗的交通特性的基侦,热点可能发展与温度上上升达70摄氏度.这可能彩响孔隙度的床上。这个热量的消退.以及监管取决干曝气生物系统,高淑影响抱于萌发、生长,Producufbrmation和SPOnJIaIiOn,低温影响不利（Moreira等人,1981）。低水分.可怜的导热系数的基侦导致较差的传热总和.因此它是特别难以维护芍利的温度在反应堆.因此水增加有连续混合足布利的总和、这可以通过适当设计的流化床反应器，蒸发冷却的虫要性和含水率的茶质生物反应器性能的社保携船被高亮显示文献来限制不断上升的温度（纳等人.2001:1.OnMnC等人.1985）。但是这种类型的冷却反应堆可能影响性能（史变茨等人.1999）.水活动还可以Ici便由于枳聚的溶版如蓟®犍、蜕基酸等.这可有效避开啮水到固体基质相合在一起.足够的水供应必需是可用的刷长或真菌也于、水活性的基质（RaghavaRao等人,2003）,在工业SSF反应堆迫使潮湿的空气或干燥的空气裾环,冷却外部表面或内部表面的反应堆.冷冻水或通过漫盅它与水泡泡机麻布是值彻去尝试限制发酵涉度.生物反应器的设计SSF流程可以分枇操作.美联储批次或连续的模式.Shearsensitivityofthesusratcandthemicroorganismmustbetakenintoaccountduringreactordesign.OVerIheperiodagoodunderSIandingofSSFItxltodesign,operateandscaleupSSFbioreactors.Theprocessisaerobicinnulureandcontainsasolid02.nutrientsandenzymestohemicrobesinthesolidsubstrule.Thesemasstransferstudiesindicateforcedcirculationofairthroughbedcanenhance02transferandCO2dissipationinthebediffluidizedbedisusedasSSEHEATTRANSFERPROB1.EMSThehe<ilgenerationisdirectlyproPOftionidtothernelabolicactivityintheSSEreactor(Chaha1.1983;RobinsonandNigan2(X)3).Asfermentationprogresses02diffusesand(riggersthebiorcactions,liberatingheatwhichaccumulatesinthereactorduecoPoOrtransportxoertyofsubstrate.Hexspotsnaj,developwithatenra(ureriseofashighas7(fC.Thismayaffectporosityofthebed.Thehealremovalandregulationdependsontheaerationofthefermentationsystem.Hightemperaturesa11ectsporegermination,growth,product-formationandsporulation,wherelowtemperaturesaffectadversely(Moreiraetal.I98l).1.owmoisture,poor(hemalConduclivilyofthesubslra(eresultinpoorheattransferinSSEHcnccitisVCrydiculttomaintainfavourabletemperatureinthercac(or.Thuswaterxkli(ionwithcontinuousmixingisfavourableinSSEwhichcanbeachievedinapropertydesignedfluidizedbedbioreactor.TheimportanceofevaporativeCOOlingcindmoistureconlentofthesubstrateontheperfomaeofSSEbiorcactorhasbeenhighlightedintheliteraturetocontroltherisingtemperature(Nageletal.,2001;1.onsaneetal.,1985).Buithistypeofcoolingmayaffectthereactorrfb11nance(Sni(setal.1999).Waleractivitycouldalsodropduetobuild-upofsolutessuchasglucose,aninoacids,etc.Ihiscouldbepreventedbysprayingwateron(othesolidsubstratecoupledWithmixing.Sufficientwatersupplymusthemadeavailabletothegrowingsporesorfungi,andforwateractivityof(hesubstrate(RaghavaRaoe(al.2003).InindustrialSSFreactorsforcednwistairordryaircirculation,coolingtheexternalsurfaceorwithinternalsurfaceofthereactorwithchilledwaterOrbycoveringitwithwatersoakedburlapareworthcrying(ocontrolthefcmnaliontemperature.BIoREACTORDESIGNSSFProCeSSeScouldbeoperatedinbatches,fedbatchesorcontinuousies.然而对于瓜佳颗粒大小和结构惶改发酵前有待发觉试验虽然预处理技术像蒸、膨化、挤压等可以适应的增加相界面枳和可访问性的02、养分和酹激生物在固体基质。这床的水分及孔隙度.社保基金的生物反应零系统应满意以下需求.个合适的容器带固体基质1这个材料的结构应当被机械的强壮,无毒,抗腐蚀和更少的成本.2.环境友好.应当能修限制bidmissions在其操作.3,应当配备限刎和监管机构时有效的通风、混合、除去热t和水分限制。4 .杀菌机制（原位或肉线）5 .平安装卸和产品回收系统.液态深层发酵系统相匕社保基金生物反应源统尚未达到成熟和完善（尼陶.N9X）克服这些何阳的传热、传质现象和简洁扩散氧气,二氧化碳和其他代谢产物,一个合适的生物反应器的设计是未实现的（Pandey.I994）,温度和水分维护反应器中不利于已成为主要议虺的探讨.很多生物反应渊的设计就像托盆类型、埴科床、旋转、摇摆鼓、搅拌突型提出了最近（杜兰凄.2003）。大规模扩散机制和限制,在间隙和国米粒子转移产品的气体和氧气很明显被理解为高效的设计（RaghaVilRao等人.2003）。最近.一个特定于产品的生物反应器称为P1.AFR.ACTOR（摩马尔2001）被文班报道制药生产.另一位现代SSF生捌反应器生产M/SFujiwara11本（2000年）。全部上述反应堆遭遇介理限制设计参数.如湿度、辄转移、温度等.要解决这些问题一个良好的计售机限制流化床反应器正在建设的影响,提出了探讨的动物SSFPKC和家意饲料在嗯.沙巴.测量和限制参数的总和测量和限制的状态或操作变小,以获得更好的性能是至关里要的反应堆.Moisture,temperature,oxygenandgaseousproductslikeCO2concentrationsarctobeaccuratelymeasuredon-lineaxlcomrolledIbrgoodfem>eHa（ionandPrOdglyieldatpl11nu11levels（Fernandeze<al.1997>.TheoperatingSubslralebedwithmoistureandporosity.TheSSFb沁reaclorsystemshouldfulll(hefollowingrequirements.1. Asuitablevesselforholdingthesolidsubstrate.Themateria!ofconstructionshouldbenechanicallystrong,nonoxickCOITOSiOnresistantandlesscost.2. Envi11)nrnenlalfriendly.Shouldbeabletocontn)llhebio-emissionsduringitsoperation.3. ShouldbeequippedwithcontrolsandregulatorsforCfYccliveaeration,mixing,heatremovalandmoisture>nirol.4. Slerilizalionmechanisms(in*siluOroff-line)5. Safeloadingandunloadingandpxxltrecoverysystems.Incontrast<osubmergedfermen(a(ionsystems.SSFbioreactorsystemsareye<(oreachSophislicaliiHiandperfection(Nigam.1998).Toovercome(heproblemsofhealandmasstransferphenomenaandeasydilTusionof02.CO2andothermetabolites,asuitablebioreac(ordesignisyettobeachieved(Parlcy,1994).TemperatureandconducivemoisturemaintenanceintheactorhavebeconIhemaintopicsforreseah.ManybioreactordesignslikeIraytype,packedbed.rtXclng.rockingdrum,stirredIyPChavebeenPrOPOSedrecently(Durand.2(X)3).Massdiffusionmechanismsandlimitations,intheintersticesandinterparticleCransfcrofbyproductgassesari02arecobeunderstoodclearlyforef11ciendesign(RaghavaRaoetal.2003).Recently,aProduClspecificMoreaclorcalledP1.AFRACToR<Kumar.2001)hasbeenvportedinliteratureforpharmaceuticalproduction.AnothermodemSSFbiorcactorisbeingmanufacturedbyM/SFujiwara,Japan(2(XX).AllOflbCabovereactorssufferfromPrOpercontlofdesignParameerslikehumidity,oxygentransfer.IemPeralU代e(c.TbaddresstheseproblemsagoodcomputercontrolledfluidisedbedbioreactorisproposedandisunderconstructiontostudylheSSFofPKCtoanimalandpoultryfeedatUMS.Sabah.MEASUREMENTANDCONTRO1.OFSSFPARAMETERSMeasurementundConIrolofstateorope11dngvariablesisCnJCidlforbelterperfo11nanceofthereactors.剪切敢4性的堪质和微生物必需考虑在反应堆设计。在这段时期内的良好理解SSF导致设计,操作和扩大SSF生勒反应涔。这个过程是有氧性质,并包含一个固体荔侦6. 生物质生产及其动态.7. PH值和水活性的改变.8. 在生理学的生物量改变.这种志向的模型可能恒久不会实现.但一些关键的参数可以嵌入在模型来描述其正的特征的过程从而最大化SSF经济性能.动能和输运模型的系统将梢助SSF在设计.开发.经营的商业反应堆(多利等人.I992),几何和动态相像的方法将一个基本原理和现实的个川干扩大SSF反应堆.拉纲分析&数的影响总体性能的校长必再做批列性的牢靠的扩大。像雷诺兹少的域度数据NUSSd电大坝克勃.韦伯,Prandde等必浦适合描述仿真的条件在工业反应堆通过试验室反应堆数据.以保证适应性.在设计商业核反应堆.压际标准超的一个可能犷大的因素要探究.没有信息我征的传热传质系数在SSF反应堆至今。有必要制定模型试验工作对压降、质量和传热系数在SSFIabscalc生物反应器中采纳商业单位。SSF的应用在全球趋势在SSF探讨潜在的应用SSF分心I.农业残留物转化为塔伯和蛋白质丰富的终端产品为东禽和牲帮的饲料.残留喜赞咖啡纸浆和壳、大豆、木售皮、蔗渣、甘蔗蔗渣、甜菜浆、水果废弃物,榇桐树废物等及其转化为乙呼.单细胞蛋白、有机酸像柠愫和乳酸.aminoacids、颔科、抗生素、解菇、生物农药、赤忒素、风味和存气化合物等.这种六苗文化对咖琲克制作了一个强大的酒鬼.果实风味成分的香气如端稀、甲褴、乙醉、乙酸clyl.主要有物侦的产量.头部空间的文化组成的化合物在图1中给出。Citricacidisprobablytheonlyproduct-producedonlargetonnage5(M),(XX)t/yrbyfermentationwhichisusedinfoodandpharmaceuticalindustry(Scc<>le(al.2003).Manybacteria,yeaslandfungiarccapableofgrowthnsolid7. pHandwaleractivitychanges.8. (Thangcinphysiologyofthebiomass.Suchanidealmodelmayneverbeachievedbutsomeof(hecriticalPmralneieNcanbeembeddedinthemodeltodescribelhctruecharacteristicsofSSFprocessestherebymaximizingtheirCCOnomiCperformance.'l*hcknc<icandtransportmodelsofSSFsystemwillhelpinthedesign,developmentandoperationofCOmmCrCialreactors(Doelleet;il.1992).Geometricanddynamicsimilarityapp11chWiHbedrationaleandrealisticoneforscale-upofSSFreactors.DimensionalcnalysisoftheparametersaiYcctingtheoverallpcribmunccoftherectormustbedonecriticallyIbrareliablescale-up.ThedimensionlessnumberslikeReynolds,Nusselts,DamKoehler,Weber,Prandtleetc.mustbeadapted(odescribe(hesimulationof(hec