Technical use of microbial enzymes
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This document discusses the application of microbial enzymes in various industries. It covers their use in the textile industry for processes like desizing, scouring, bleaching, biopolishing, and denim finishing. It also discusses the application of microbial enzymes in the leather industry for processes like soaking, liming, dehairing, bating, and degreasing. Finally, it discusses the use of microbial enzymes like sialidases and mucinases in diagnostic purposes for detecting diseases like bacterial vaginosis.
Technical use of microbial enzymes
- 1. ShaheenAlam 1 Technical use of Microbial Enzymes I will discuuss here only on folloeing topis 1. Application of Microbial enzymes in Textile Industry 2. Application of Microbial enzymes in Leather Industry 3. Application of Microbial enzymes in Diagnostic purposes Topic no. 1:- Application of Microbial enzymes in Textile Industry The use of microbial enzymesintextile industryisone of the mostrapidlygrowingfieldinindustrial Enzymology because Historically,the use of enzymesinthe textile industrybeganin1912 withthe use of barleyforstarch sizingfromwovenfabrics.The firstmicrobial enzyme, ‘amylase’,wasusedin1950 for the same starch desizingprocessthatisnowadaysaroutine procedure.Today,microbialenzymes are importanttoolsinthe textile industry,astheirnon-toxicandeco-friendlycharacteristics withthe increasinlyimportantrequirementsfortextilemanufacturestoreduce pollutionintextile production Presently,the textile industryisemployingan arrayof approximately75 enzymesthatcouldbe broadly groupedas oxidoreductasesandhydrolases.The differentprocessesinwhichenzymesfindapplication are :- 1) textile desizing, 2) enzymaticscouring, 3) denimfinishing, 4) biopolishing, 5) degummingof silk, 6) and fiberprocessing.
- 2. ShaheenAlam 2 Table: Microorganismsproducing enzymesoftextile important Enzyme applications intextile preparatory process 1) Enzymatic Desizing Cottonor blendedfabricsuse warpthreadscoatedwithadhesive knownas‘size’.Size helpsin lubricating,thusprotectingthe yarnfromabrasionandpreventingthe threadsfrombreakingduring weaving.Starchandits derivativesare mostcommonlyusedforthisprocessastheyhave excellent filmformingcapacity,are easilyavailable,andare relativelycheaper.Afterweaving,the sizingagentand othernon-cellulosicmaterial presentonthe cottonfibermust be removedforthe processof dyeingand finishing. In the textile industryamylasesare usedtoremove starch-basedsize forimprovedand uniformwetprocessing.Amylaseisahydrolyticenzymewhichcatalysesthe breakdownof dietary starch to short chainsugars,dextrinandmaltose.The advantage of these enzymesisthattheyare specificforstarch,removingitwithoutdamagingtothe supportfabric.Anamylase enzyme canbe used for desizingprocessesatlow-temperature (30-60ºC) andoptimumpHis 5.5-6.5 . 2) Enzymatic Scouring (Bioscouring) Untreatedcottonor greige containsvarietiesof cellulosicimpuritieslikewaxes,pectins,and hemicelluloses,whichgive hydrophobicpropertiestothe fiberandtherebyinterfereinthe processof dyeingandfinishing.Thus,scouringiscarriedouttoremove these impuritiesandenhance wettabilityof
- 3. ShaheenAlam 3 the fiber.Thiswas previouslyconductedwithchemical methods;however,nowadaysbioscouringis carriedout usingmicrobial enzymes likepectinases,proteases,lipases,andcutinases – individuallyor incombination. Pectinasesisageneral termappliedforpectinesterases,polygalacturonases,andpectin lyases. In thispectinasedestroythe cotton cuticle structure (Cuticleis a thin layerof cutin and Cutin is polyester composed of epoxy and hydroxylfatty acids.) bydigestingthe pectinandremovingthe connection between the cuticle andthe bodyof cottonfibre whereas cellulasecandestroycuticle structure by digestingthe primarywall celluloseimmediatelyunderthe cuticle of cotton.Cutinases (cutinasefroma bacterial source, P. mendocina ) are hydrolyticenzymesthatdegrade the cutin .Handle isverysoftin enzymaticscouringcomparedtoharshfeel inalkaline scouringprocess.Enzymaticscouringmakesit possible toeffectivelyscourfabricwithoutnegativelyaffectingthe fabricorthe environment.It also minimiseshealthrisksenceoperatorsare notexposedtoaggressivechemicals . 3) Enzymatic Bleaching The purpose of cotton bleachingistodecolourise natural pigmentsandtoconfera pure white appearance tothe fibres.Mainlyflavonoidsare responsible forthe colourof cotton. The most common industrial bleachingagentishydrogenperoxide.Conventional preparationof cottonrequireshigh amountsof alkaline chemicalsandconsequently,huge quantitiesof rinse waterare generated.However, radical reactionsof bleaching agentswiththe fibre canlead toa decrease inthe degree of polymerisationand,thus,tosevere damage. Therefore,replacementof hydrogenperoxide byanenzymaticbleachingsystemwould notonlyleadto betterproductqualitydue tolessfibre damage butalsoto substantial savingsonwashingwaterneeded for the removal of hydrogenperoxide.Analternative tothisprocessistouse a combinationof suitable enzyme systems.Amyloglucosidases,pectinases,andglucoseoxidases are selectedthatare compatible concerningtheiractive pHand temperature range. Some researchabstractson bioleachingare givenbeow- i. Tzanovet al.(2003) reportedforthe firsttime the enhancementof the bleachingeffect achievedoncottonfabricsusinglaccasesinlow concentrations.Inaddition,the shorttime of the enzymaticpre-treatmentsufficienttoenhance fabricwhitenessmakesthisbio-process suitable forcontinuousoperations. ii. Also,Pereiraetal.(2005) showedthata laccase froma newlyisolatedfungal strainof Trametes hirsuta, wasresponsibleforwhitenessimprovementof cottonmostlikelydue tooxidationof flavonoids. iii. More recently,Bastoetal.(2006) proposeda combined ultrasound-laccase treatmentforcotton bleaching.Theyfoundthatthe supplyof low ultrasoundenergy(7W) enhancedthe bleaching efficiencyof laccase oncottonfabrics.Natural fabricssuch as cottonare normallybleachedwith hydrogenperoxide before dyeing.Catalaseenzyme isusedtobreakdownhydrogenperoxide bleachingliquorintowatermoleculesandlessreactivegaseousoxygen.Comparedwiththe
- 4. ShaheenAlam 4 traditional clean-upmethods,the enzymaticprocessresultsincleanerwaste waterorreduced waterconsumption,areductionof energyandtime. 4) Biopolishing Biopolishingisafinishingprocessthatimprovesfabricqualitybymainlyreducingfuzzinessandpilling propertyof cellulosicfibre.The objectiveof the processiseliminationof microfibrils of cottonthrough the action of cellulaseenzyme .The maincharacteristicsimpartedtothe fabricduringbiopolishing treamentare as follow: i. Cleanersurface isobtainedconferringacoolerfeel. ii. Lustre is obtainedasa side effect iii. Fabricobtainssofterfeel. iv. Tendencyof the fabricto pill ends. 5) Enzymatic treatment to denim Denimsare basicallycottoncloththat isconventionallydyedwithindigo,havingacharacteristicblue color.The stonewashorwornlookispopularindenimfinishingandwasinitiallyachievedbylaundering the denimwithabrasive pumice stones (sodiumhypochloriteorpotassiumpermanganate). Disadvantage of these methodare asfollows: i. Pumice stonescause large amountof back-staining. ii. Pumice stonesare requiredinverylarge amount. iii. Theycause considerable wearandtearof machine. These disadvantagesleadtogive rise the processof use of enzymes.Cellulase enzymeisusedindenim washing. Cellulasepossessasimilaractionbylooseningthe indigodye fromthe denimfibers,givinga fadedabradedlook similartothatprovidedbythe stones ina processknow as “BioStonewashing”.A small dose of enzyme canreplace several kilogramsof pumice stones.The use of lesspumice stones resultsinlessdamage togarment,machine andlesspumice dustinthe laundryenvironment. More recently,some authors showedthatlaccase wasaneffective agentforstonewashingeffectsof denim fabricwithand withoutusingamediator .
- 5. ShaheenAlam 5 Table: Enzymesusedin textile and theireffects Table: Applicationof hydrolase enzyme infabric production
- 6. ShaheenAlam 6 Table: applicationof oxidoreductase infabric preparation Topic no. 2:- Application of Microbial enzymes in Leather Industry Leather Industry :- Microbial Enzymeshave beenusedintanneriesandthe leatherindustryforcenturiesastheywere efficientindegradingthe proteinandlipidcomponentsof the hides/skin.Inearlydays,these enzymes were derivedfromanimal excretaandlaterthe pancreas of cattle. Leather-processingindustriesinvolvemanysequential stepsfromraw hidestoprocessedleather.The stagesof leatherprocessingare :- i. preservation, ii. soaking, iii. liming, iv. dehairing, v. flashing, vi. splitting, vii. reliming, deliming, viii. bating, ix. degreasing, x. frizzing, xi. beaching, xii. pickling,depickling, xiii. and tanning.
- 7. ShaheenAlam 7 Raw hidesundergomanyof these treatmentsinacascade mannerbefore itisconvertedintofinished leather. Disadvantageofconventional Leather processing The pre-tanningoperations requirethe use of harshchemicalsinlarge amounts,hence the leather industryisone of the worst environmental pollutionoffenders. Advantageof microbial enzymein Leather processing 1) Duringleathermanufacturing,the non- collagenousconstituentsof raw hidesare completely removedduringpre-tanningoperations,of whichdehairingisone of the majorprocesses. Dehairingisthe single largestprocessinthe leatherproductionprocessandrequiresahuge numberof enzymeslike proteases,amylases,and lipasestomake the processenvironmentally friendly. 2) Today,microbesserve asresourcesof highlyspecificenzymesthatare fastintheiractionand are therefore usedintanneriesforsoakinganddehairingprocesses. 3) Otheradvantagesof usingthese enzymesincludethe replacementof harmful chemicalsthat pose a threatto the environmentandreductionsinprocessingtimesandproductioncosts Role of enzymes indifferent Leather processing stages :- 1) Curing : Curingof the hide isdone to preserve themsotheydonotspoil before theyare subjecttofurtherprocessingforleatherdevelopment.Hidesare steepedinabrine bathand driedinthe sun; saltisaddedto the fleshside. 2) Soaking :- Soaking isthe first tanningoperationthatinvolvesthe treatmentof hideswith water.Soakingisusedto rehydrate the skin.The degree of rehydrationaffectsthe qualityof leather;the betterthe rehydration,the superiorthe leather.Soakingsolutionsgenerally comprise surfactantsandantimicrobial compounds.Ithasbeenfoundthatbrine andcured hides,whensoaked inproteaseinthe presence of surfactants,reducedthe soakingtime by45 %,and sulphidesreducedby40 %. 3) Liming :-Limingisemployedonimproperlysoakedskin.These are re-soakedinmilkof lime so that the desiredswellingof collagentakesplace andopensupthe fiberbundles.The
- 8. ShaheenAlam 8 objective of thisprocessistoremove hairs,nails,hooves,andotherkeratinousmaterials. Alkalineproteases andalkalinelipases are usedin the processof soakingand liming.The protease will openthe membranesaroundthe fatcells,makingthe fataccessible tolipase, resultinginthe breakdownof fats.Furthermore,the breakdownproductsshall emulsifyintact, whichshall distributethroughoutthe feltomittingthe use of degreasingsurfactants.NovoLime ® is a protease/lipaseblendforenzyme-assistedlimingof hidesandskins. 4) Dehairing : Dehairinginvolvesthe removingof hairsfromthe hideswithoutdamagingthe hide,whichdependsonthe phenomenonof hairloosening.Specific proteasesare requiredthat can remove the hairwithoutdamagingthe fibrouscollagen.Clarizyme® is an alkalineserine protease from Aspergillus flavus by the Central LeatherResearchInstitute (CLRI),Chennai, India,forthe dehairingof skinandhides.ProteasesfromBacillusand Streptomyces have been usedforenzymaticdehairingprocesses. 5) Bating :- Bating isa processof beatingthe leather cruellywithaheavystroke usingwooden logsand metal rods.Thisprocessiscarried outto loosenandpeptize non-collagenousskin structuresviaremoval of interfibrillaryproteins,epidermis,andscuds.Forthe productionof soft pliable leather,usedformakingpursesandgloves,astrongbeatingprocessmustoccur. Thisprocessis generallycarriedoutinthe presence of proteolyticenzymesofbacterial origin.Effective batingoccurs underalkaline conditionsconductedat95–100 °F (30–38 °C) between apHof 7.5 and8.5 or else the enzyme efficiency. 6) Degreasing :- Grease removal intanneryiscarriedout vialiming.However,the grease contentinsome hides/skinsishigherandcausesfattyacid spuesandunevendyeingand finishing.A variety ofmicrobial lipases have beenusedfordegreasing.The beststage of degreasingispickling,asall the fatdepositsare available tothe surfactants.Since picklingisan aqueousphase,acombinedactionof disruptionof fatcellsandtriglyceride splittingoccurs, therebyimprovingthe degreasingprocess. 7) Tanning :-Tanningis the laststage of leathermanufacture whereincollageniscross- linked to the active groupof the tanningagent,therebyirreversiblystabilizingthe skinthatisprone to putrefaction.Thismakesthe collagenresistanttobacterial,enzymatic,andacidattack.
- 9. ShaheenAlam 9 Topic no. 3:-Application of Microbial enzymes in Diagnostic purposes Diagnosticenzymesare definedasa componentof an assaysystemfordeterminationof manydifferent substances.These are generallyemployedfordiagnosis/biomarkersof diseasesanduse blood,serum, and urine foranalysis.Microbial enzymesare alsoused asindicatorsorbiomarkersof a disease. 1) Sialidasesare bacterial enzymesthatplaya role incellularinteractions,bacterial nutrition,and immune response evasion,thusimprovingthe bacterial abilitytoadhere to,invade,anddestroy the mucosal tissue.Sialidasesoccurinbacteria,mycoplasma,protozoa,fungi,andviruses. Bacterial vaginosis(BV) isadisorderof the vaginal ecosystemcharacterizedbyashiftinthe vaginal flora formthe normallypredominant Lactobacillus tomixedflora,including Gardnerellavaginalis, Mobiluncus, Prevotella,Bacteroides,and Mycoplasma species.BVBluesystem(GryphusDiagnostics, L.L.C.) isa chromogenicdiagnostictestbasedonthe presence of elevatedsialidase enzymesinvaginal fluid samples. 2) Microbial mucinases(mucin-degradingenzymes)are associatedwithgenital tractconditions and sexuallytrans-mitteddiseases(STDs).
- 10. ShaheenAlam 10 Table: Exampleof microbial enzymesused for analytical,diagnosticandtherapeutic purposes