h tt p : / / w w w . b j m i c r o b i o l . c o m . b r /
Environmental
Microbiology
Degradation
of
textile
dyes
by
cyanobacteria
Priscila
Maria
Dellamatrice
a,
Maria
Estela
Silva-Stenico
b,
Luiz
Alberto
Beraldo
de
Moraes
c,
Marli
Fátima
Fiore
b,
Regina
Teresa
Rosim
Monteiro
a,∗aCentrodeEnergiaNuclearnaAgricultura,LaboratóriodeEcologiaAplicada,Piracicaba,SP,Brazil
bCentrodeEnergiaNuclearnaAgricultura,LaboratóriodeBiologiaCelulareMolecular,Piracicaba,SP,Brazil cUniversidadedeSãoPaulo,DepartamentodeQuímica,RibeirãoPreto,SP,Brazil
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Articlehistory:
Received31October2015 Accepted20July2016
Availableonline10October2016 AssociateEditor:ValeriaMaiade Oliveira Keywords: Dyes Toxicity Discoloration Cyanobacteria Degradation
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Dyesarerecalcitrantcompoundsthatresistconventionalbiologicaltreatments.The degra-dationofthreetextiledyes(Indigo,RBBRandSulphurBlack),andthedye-containingliquid effluentandsolidwastefromtheMunicipalTreatmentStation,Americana,SãoPaulo,Brazil, bythecyanobacteriaAnabaenaflos-aquaeUTCC64,PhormidiumautumnaleUTEX1580and Syne-chococcussp.PCC7942wasevaluated.Thedyedegradationefficiencyofthecyanobacteriawas comparedwithanaerobicandanaerobic–aerobicsystemsintermsofdiscolourationand toxicityevaluations.Thediscolorationwasevaluatedbyabsorptionspectroscopy.Toxicity wasmeasuredusingtheorganismsHydraattenuata,thealgaSelenastrumcapricornutumand lettuceseeds.Thethreecyanobacteriashowedthepotentialtoremediatetextileeffluent byremovingthecolourandreducingthetoxicity.However,thegrowthofcyanobacteria on sludgewasslowanddiscolorationwasnotefficient.ThecyanobacteriaP.autumnale UTEX1580wastheonlystrainthatcompletelydegradedtheindigodye.Anevaluationof themutagenicitypotentialwasperformedbyuseofthemicronucleusassayusingAlliumsp. Nomutagenicitywasobservedafterthetreatment.Twometaboliteswereproducedduring thedegradation,anthranilicacidandisatin,buttoxicitydidnotincreaseafterthe treat-ment.Thecyanobacteriashowedtheabilitytodegradethedyespresentinatextileeffluent; therefore,theycanbeusedinatertiarytreatmentofeffluentswithrecalcitrantcompounds. ©2016SociedadeBrasileiradeMicrobiologia.PublishedbyElsevierEditoraLtda.Thisis anopenaccessarticleundertheCCBY-NC-NDlicense(http://creativecommons.org/ licenses/by-nc-nd/4.0/).
Introduction
Syntheticdyesarerecalcitrantmoleculesthatconstitutethe mainresiduefoundintheeffluentofthetextiledyeing indus-try.Acute toxicity tests showed that most textile dyesare
∗ Correspondingauthorat:CentrodeEnergiaNuclearnaAgricultura,LaboratóriodeEcologiaAplicada,C.P.96,13400-970Piracicaba,SP,
Brazil.
E-mail:monteiro@cena.usp.br(R.T.Monteiro).
not particularly toxic.1 Nevertheless, their persistence and
resultinglongexposuretimeisofparticularconcernforthe dischargeofwastedyeeffluent,sincethesesubstancesmay exhibitchroniceffectssuchasmutagenicdamageand car-cinogenicitytowards biota.2,3 Several authorsreported that
dyedischargesfromtextileprocessingplantswerethemajor
http://dx.doi.org/10.1016/j.bjm.2016.09.012
1517-8382/©2016SociedadeBrasileiradeMicrobiologia.PublishedbyElsevierEditoraLtda.ThisisanopenaccessarticleundertheCC BY-NC-NDlicense(http://creativecommons.org/licenses/by-nc-nd/4.0/).
contributors to the mutagenic activity found in Brazilian rivers.4,5
Insometextiledyeingoperations,asmuchas15%ofthe dyes used do not attach to the fibres, so they are lost to wastewater,6andtheresultingcolouredeffluentscan
repre-sent aserious waterpollution problemdue totheircolour contentandtoxiccomponents.Theusualeffluenttreatment involves biological systems like activated sludge; however, conventionaltreatmenthasnotefficientlyremovedthe efflu-ent dyeduetothe recalcitrant natureofthe dyesand the diverse composition of the effluent.7 A tertiary treatment
of effluents is recommended for the removal of nutrients and recalcitrant substances, whichis done mainly by sev-eral algaespecies. Studies haveshown the abilityofsome algaetodegradedyes,8–11 makingtertiarytreatmentaviable
possibilityfortheefficientdegradationofthesecompounds. Vyayakuma and Manoharau12 studied the degradation by
indigenouscyanobacteriumspeciesofatextileeffluent con-taining the dyes remazol and venyl sulfone and observed not only colour removal, but also reduction in the levels of the inorganic compounds such as nitrites, phosphates, ammonia, calcium and magnesium. The main cyanobac-terium strains reported to be responsible for the removal of nutrients and chemicals from the industrial effluents wereWestiellopsissp.,Lynghyasp.,Oscillatoriasp.andChlorella sp.12–15
Theenvironmentalproblemcausedbyhazardousdyesis particularlyimportantintheMunicipalTreatmentStationof Americana,SP,Brazil,whichisresponsibleforthetreatment ofeffluentsfrom43textileplantsaswellascitysewage. Peri-odicreleases ofliquid effluentfrom this treatmentstation werecarriedtothePiracicabaRiver,adomesticwatersource forcitiesdownstream.Thebiologicaltreatmentemployedis efficientforBODremoval, but the colourpersistsafterthe treatment,makingthistreatmentinsufficienttoremovethe contaminantsfromtheeffluent.Inthepresentstudy,three strainsofcyanobacteria,Anabaenaflos-aquaeUTCC64, Phormid-iumautumnaleUTEX1580andSynechococcussp.PCC7942were evaluatedfortheirabilitytodegradethreedifferentdyes:RBBR (RemazolBrilliantBlueR),indigoandsulphurblack,andalso thedye-containingliquideffluentandsolidwastefromthe MunicipalTreatmentStationofAmericana(SP,Brazil) contain-ingthosedyes.
Materials
and
methods
Cyanobacterialstrains
The cyanobacteria were filamentous heterocystous A. flos-aquaeUTCC64,thefilamentousnon-heterocystousP. autum-nale UTEX1580, and unicellular Synechococcus sp. PCC7942, all from the Culture Collection of the Centro de Energia NuclearnaAgricultura–CENA/USP.Thesestrainswerechosen basedon astudybyFiore andTrevors16 on the
bioremedi-ation ofmetals bythecyanobacterium,inwhich the three selectedstrainshadthehighestdetoxificationcapability.The organismsweremaintainedinflaskscontaining50mLofAA medium17 forA.flos-aquae UTCC64,orBG-11medium18 for
P.autumnaleUTEX1580andSynechococcusPCC7942;1mLfrom
thesesevendaycultureswasusedtoinoculatethedifferent treatments.
Textilewastesampling
Liquid effluentwassampled (3L) afterbiologicaltreatment (biological filters) and the sludge also was sampled (3kg) after aerobic-anaerobic treatment in the Municipal Treat-ment Station of Americana, SP, Brazil.Samples were kept at 4◦C until use. Both of these residues still contained a highamountoforganicsafterthetreatment,andremained strongly-coloured.
Dyediscolorationbycyanobacteria
ThesyntheticdyesRBBR[(RemazolBrilliantBlueR)purchased fromSigma(Sigma–Aldrich,St.Louis,MO,USA)],indigoand sulphurblack(Bayer,SãoPaulo,SP,Brazil),wereaddedata concentrationof0.02%(m/v)toErlenmeyerflaskscontaining 50mLofAAorBG-11culturemedia.Eachflaskwasinoculated with1mLofthecyanobacteriumculturemedium,in tripli-cate. Theeffluent and thesolid waste,whichwere diluted toaconcentrationof10%inanAAoraBG-11media,were treatedinthesamewayasthedyes.Allofthetreatedflasks were incubated for14 days at25◦C with constant fluores-centillumination(4000±10%lux).Controlexperimentswere conducted in light and dark conditions in the absence of microorganisms toevaluatetheeffectofphotodegradation. Thediscolorationwasevaluatedbyabsorptionspectroscopy. Theabsorptionmaximumforeachdyewas680nm(indigo), 595nm(RBBR)and454nm(sulphurblack).Thesampleswere centrifugedat10,000×gforfiveminandthecolourreduction was based on astandard curve comparing dye concentra-tion inthetreatmentsinrelationtonon-inoculatedcontrol flasks.
Ananaerobic–aerobicdegradation systemwasalso eval-uated for dye discoloration in the liquid wastewater. The anaerobicconditionswereobtainedbycompletelyfillingthe triplicate 150mL penicillin bottles with the effluent, and sealingthemwithrubbertopsinaCO2atmosphere.The
bot-tles were kept for15 days at28◦C in the dark. Then, the bottles were opened and 50mLofeffluent wastransferred to sterilized Erlenmeyer flasks and re-enriched with 1mL ofinoculum obtainedfrom afresheffluent. Thisinoculum waspreparedthroughcentrifuging(2000×g)100mLoffresh effluentandresuspendingthepelletsinsaltsolution(0.85% NaCl). Theflaskswere incubated aerobicallyfor15daysat 28◦C.
Toxicityevaluationofthetreatedeffluentandsludge
Thetoxicityoftheeffluentandsludgewasevaluatedusing the bioindicatororganismsHydraattenuata, thegreenalgae Selenastrum capricornutum and root growth of Lactucasativa seedlings.TheseorganismsaremaintainedatCENA/USPand bioassays were conductedas described byTrottier et al.,19
Blaiseetal.,20andDutka,21respectively.The50%inhibitory
concentrations(IC50)weredeterminedforeachsampleusing
BiodegradationoftheindigodyebyPhormidiuminthe bioreactor
ThebiodegradationofindigodyebyP.autumnaleUTEX1580, thestrainthatshowedthehighestpercentageofindigo dis-colorationintheprevioustests,wasfurtherstudiedina15cm wide,60cmhigh,6Lbioreactor.Inpreparationforthe inocula-tion,P.autunmnalewasgrownpreviouslyin500mLofaBG-11 mediumfor14 days.Thebioreactor received constant aer-ationandillumination byfour verticallyplacedlamps. The indigodyewasaddedtoaconcentrationof0.02%inthe BG-11culturemedium.Thecontrolwaskeptinthedarkat4◦C. Samples were collected on days 2, 4, 7, 14, 15, 16, 17, 18 and19forabsorptionspectrophotometry analyses(583and 680nm)andtoxicitybioassayswithHydraattenuatta. Biodegra-dationwasmonitoredbymassspectrometryanalysisusing a hybrid quadrupoletime-of-flight (Q-TOF) high resolution (7000)andhigh accuracy(5ppm)Q-TOF massspectrometer (Micromass,Manchester,UK)equippedwithanelectrospray ion source (ESI). The conditions for the positive ESI were: nitrogengasdesolvationat180◦C,capillaryheldata poten-tialof3.5kVandaconevoltage25kV.Growthcultureswere centrifugedat10,000×gfor10minandthesupernatantwas mixedwith0.5mLofmethanol: formicacid1%(50:50,v/v) and introduced into the ion source at 5Lmin−1 with a syringepump.Duringthefinalincubationperiod(19days),the cyanobacteria-incubatedmediumwasassessedforits muta-genicitypotentialusingtheAlliumsp.micronucleusassayas describedbyFernandesetal.22andtoxicitybytheHydra
bioas-say.
Results
Dyediscolorationbycyanobacteria
TheCyanobacteriumPhormidiumwasabletodecolorizethe indigodyeextensively (91%),but wasnotabletodecolorize the sulphur black and RBBR dyes. Low discoloration was produced bySynechococcus for all three dyesand Anabaena was able to degrade the indigo, but the discoloration per-centage was lower than for Phormidium (Table 1). The sulphur black was decolorized by Anabaena, which pro-ducedonly a partial degradation.The three strains tested wereabletoremovethe effluentcolour,but for Synechococ-cus a decrease in absorption was not detected because theabsorptionmeasureswere affectedbythegreencolour of the cultures (Table 1). Phormidium caused more colour removalthanAnabaenaand,forSynechococcus,visual discol-oration seemed higher than the methodology was able to detect.
For the anaerobic–aerobic system, 17% and 33% discol-oration was obtained after anaerobic treatment and the combined anaerobic–aerobic one,respectively. The anaero-bicdegradationresultedincolourremoval,butproducedan effluentwithhigh turbidity,whichwasremovedbyaerobic degradation.Thesecompoundsrequirethepresenceofa com-bination of anaerobic and aerobic conditions for complete degradation,sincetheyareverycomplexandrecalcitrantdue totheirxenobioticcharacter.
Toxicitytestsontheeffluent
Thecyanobacteriumtreatmentwasabletoreducetheeffluent toxicityandshoweddegradationofthecompoundspresent intheeffluent.Therewasgrowthinhibitionoftheorganism Selenastruminthelightanddarkcontrols;however,therewas nogrowthinhibitionintheeffluenttreatedbythe cyanobac-teriumstrains.
In the lettuceseeds test,toxicity was reducedafter the treatment too, as demonstrated by a lack of root growth inhibitionafterthecyanobacteriumtreatment.TheIC50
deter-mination(concentrationthatinhibited50%oftheorganism growth) was possibleonlyforthe darkcontrol (IC50=95%),
whereasothertreatmentsshowedlessthan50%inhibitionat themaximalconcentration(Table2).
IntheHydratest,ahigherLOECandNOECwereobserved aftertreatmentwiththethreestrains.SinceLOECisdefinedas thelowobservedeffectconcentrationandtheNOECisdefined asthenoobservedeffectconcentration,thecyanobacterium treatment resultsinatoxicity reductionforthe organisms (Table2).
Inthesludge,thePhormidiumtreatmentcausedanincrease inthetoxicity(Table2),whereastheAnabaenapresentedthe highesttoxicityreductioninthelettuceseedstest.Theslight toxicityreductionshowninthesludgebyPhormidiumand Syne-chococcusintheHydratest(Table2)meansthatalthoughthe algalgrowthwasslow,somedegradationdidoccur.Thesludge detoxificationwaslowerthanthatoftheeffluent, demonstrat-ingthatthisresidueismoreresistanttothedegradationand thatthecyanobacteriastrainwithmoreefficiencyinsludge detoxificationisdifferentthanthemosteffectiveoneforthe effluent,sinceAnabaenashowedmoresludgedetoxification thanPhormidium.
There wasmoretoxicity inthe darkcontrolthan inthe lightonesuggestingthatphotodegradationcontributedtothe detoxificationprocessinsuchconditions.
Toxicitytestsfortheanaerobic–aerobicsystem
For the Hydratest, therewasno reductionintoxicityafter anaerobictreatmentincomparisonwiththecontrol.However, a complete detoxification occurred after anaerobic–aerobic treatment,showingthetoxiccompoundswereremovedonly afteranaerobic–aerobictreatment.
Thealgaltestdemonstratedthesameresults;notoxicity reductionafteranaerobictreatmentandcomplete detoxifica-tionaftertheanaerobic–aerobicone(Table3).Notoxicitywas observedinthelettuceseedstestforanyofthetreatments, notevenfortheeffluentcontrol.
Biodegradationoftheindigodyeinabioreactor
The indigo dyebiodegradation byPhormidium was demon-stratedbycompletediscolorationafter19daysofincubation. Colourremovalwasenhancedafter14days,showingthata periodofacclimatizationwasnecessary.After19daysthere was nomorecolourleft.Thecultured cellsadhered tothe bioreactor wall, leaving a biofilm formation that adsorbed someoftheindigodye.DyediscolorationisshowninFig.1.
Table1–Percentageofeffluentandsludgediscolorationbycyanobacteriaafter14daysincubationat25◦C.
Treatment Indigo RBBR Blacksulphur Effluent Sludge Darkcontrol 0±0.001 0±0.001 0±0.001 0±0.001 0±0.001 Lightcontrol 56.14±0.057 4.0±0.001 29.41±0.002 12.90±0.006 39.28±0.006 Anabaenasp. 71.92±0.057 0±0.001 42.12±0.006 23.87±0 8.33±0.001 Phormidiumsp. 91.22±0.057 10.62±0.011 0±0.001 28.38±0.001 0±0.002 Synechococcussp. 0±0.002 11.53±0.009 0±0.002 1.29±0 0±0.002 ±Standarddeviation.
Table2–PercentageconcentrationcorrespondingtoNOECandLOECforHydraandIC50forthelettuceseedstests
conductedwiththeeffluentandsludgethathadbeenincubatedwithcyanobacteriafor14daysat25◦C.
Treatments Hydratest Seedstest
NOECa LOECb IC
50c
Effluent Sludge Effluent Sludge Effluent Sludge
Darkcontrol 6.25 6.25 12.5 3.12 94.98 17.28
Lightcontrol 12.5 6.25 25 3.12 0 51.52
Anabaenasp. 25 6.25 50 3.12 0 55.37
Phormidiumsp. 50 12.5 n.e.d 6.25 0 6.23
Synechococcussp. 25 12.5 50 6.25 0 23.89
a NOEC,noobservedeffectconcentration. b LOEC,lowobservedeffectconcentration.
c IC50,concentrationthatcaused50%inhibitionofthetestorganisms. dn.e.,noeffect.
Metaboliteanalysis
The parental indigo molecule was detectedonly until the 18thday,showingthatthedyewascompletelydegradedby Phormidiumandthatthedegradationoccurredoverthesame period that a complete discoloration was observed in the bioreactor.Afterthe17thdayofincubation,twometabolites appearedandwereidentifiedasanthranilicacid(m/z399)and isatinorindole-2,3-dione(m/z421);therefore,thedegradation oftheindigomoleculewasnotcomplete.Inthatstudy,bothof themetabolitesweredetecteduntilthe19thday,whichmeans theywerenotfullydegradedduringtheassessmentperiod.
In accord withCampos et al.,23 the first step of indigo
degradationisoxidativecleavageofthecentralbond,which produces isatin as a metabolite. Isatin might undergo hydrolysis anddecarboxylationto produceanthranilicacid (Fig.2).
Table3–Percentageconcentrationcorrespondingto
NOECandLOECfortheHydratoxicitytestandtheIC50
fortheAlgaltestafteranaerobicandanaerobic–aerobic treatment.
Treatment Hydratest Algaltest NOECa LOECb EC
50c
Control 12.5 25 73.35
Anaerobic 12.5 25 70.39
Anaerobic–aerobic 50 100 0
a NOEC,noobservedeffectconcentration. b LOEC,lowobservedeffectconcentration.
c IC50,concentrationthatcaused50%effectonthetestorganisms.
TheHydrabioassay
NotoxiceffectsweredetectedintheHydrabioassayfromthe controlindigodye,orafterthedyetreatmentbyPhormidium. Analysesperformedduringtheincubationperiodshowedthat notoxicproductswereformedduringtheperiodstudied.The presenceofthemetabolitesisatinandanthranilicaciddidnot resultinanincreaseintoxicity,suggestingthatthePhormidium treatmentofindigoisaplausibletreatment.
Themicronucleusassay
No mutagenicity effect was observed in the micronucleus assayfortheindigocontrolorfollowingthecyanobacterium treatment;therateofmicronucleusformationwasthesame forbothofthetreatmentsandforthewatercontrol. Micronu-cleicanspontaneouslyformduetoanunequaldistribution
0 10 20 30 40 50 60 70 80 90 100 20 18 16 14 12 10 8 6 4 2 0 Discoloration, % Days
Fig.1–PercentageofindigodiscolorationbyPhormidiumin thebioreactor.Standarddeviation:0.05.
O H H
Anthranilic acid
Isatin
Indigo
N N N H O O OH NH2 O OFig.2–DegradationpathwayoftheindigodyebyPhormidium.
ofgeneticmaterialduringthecellcycle.24However,therewas
anincreaseinsomechromosomalaberrations,suchas adher-ences,bridges,polyploidycellsandlatechromosomesinthe indigocontrolandfollowingcyanobacteriumtreatment com-paredwiththemineralwatercontrol(Figs.3and4).
Theseabnormalitiesconstitutesignsofmutagenicitythat indicateaninitialstageofDNAdamageinthepresenceof thedye,butthatdidnotresultinmutagenicityatthetested dyeconcentrationasdemonstratedbynoincreasein micro-nucleusformation.
Thefrequencyofcelldivisionfortheindigoand cyanobac-teriumtreatedmediumwashigherthanforthemineralwater, representinganincreaseinrootgrowthprobablybecauseof thehighamountofnitrogenandphosphoruspresentinthe BG-11medium.
Discussion
Cyanobacteria-induceddiscolorationanddetoxificationofthe effluentwasobservedforeachofthethreecyanobacteriain
thisstudy.Theseresultsshowedthatcyanobacteriawereable toreducethepollutantloadoftheeffluent.Thedegradation ofdyesbycyanobacteriaisspecies-dependent,sinceP. autum-naleUTEX1580moreefficientlydegradedtheindigodyeand A.flos-aquaeUTCC64wassuperiorinthecaseofthesulphur black.A.flos-aquaeUTCC64wasthemostefficientstrainfor sludgedecolourationanddetoxification.However decoloura-tionofthesludgewasnotsignificant,probablybecausethis residue contained more insolublehydrophobic compounds thandidtheeffluent.Acombinationofmorethanonemethod might improve the degradability of this dye-containing waste, since photodegradation was detected in the dye control.
ItseemsthatfilamentousspeciesasP.autumnaleUTEX1580 canbreakdownthedyemoreefficiently,sincethedye pene-tratesthefilaments,whichincreasesthecontactbetweenthe microorganismandthecompound.Althoughnoexperiments were performed specificallyto investigate the biosynthetic mechanisms of indigo degradation using cyanobacteria, it seemsmainmechanismmustbeenzyme-mediated,sincein thecontrolnometaboliteswereformed.
Fig.4–MutagenicitysignsfollowingtheindigodyePhormidiumtreatment:(A)polyploidy;(B)bridge;(C)latechromosomes; (D)adherence.
Phormidiumsp.wasabletodegradeseveraldyesofdifferent chemicalclasses.In astudybyShahet al.,9 the
cyanobac-teriumPhormidiumvalderianumdiscolouredupto90%ofAcid Red,AcidRed119and DirectBlack155dyes.Whenthe pH wasstronglyalkaline,anincreaseindiscolorationoccurred, whichis avery common conditionin textileeffluents due totheadditionofNaOHduringthedyeingprocess.Another strain,P.ceylanicum,alsowasfoundtodegradeAcidRed97and FFSkyBluedyesbyupto80%after26days.10Silva-Stenico
etal.25 observedgreaterthan50%degradationoftheindigo
dyeandsixotherstructurallydifferentdyesbythe Phormid-iumsp.andtwoanothercyanobacteriumstrains,Synechococcus sp.andLeptolyrigbyasp.DyedecolourizationbyAnabaenawas studiedbyQueirozandStefanelli26forBlueDrindye,andthey
showed81%colourremoval.
Thestructureofthecompoundalsoappearstobeavery importantfactor.Inspiteofthefactthatthethreedyesare veryrecalcitrant,the dyessulphurblackand Remazol Bril-liantBluehaveveryuncommonmolecularstructures,which conferahighxenobioticcharacterandgreaterresistanceto degradation.27,28InastudybyJinqiandHoutian,8dye
discol-orationwascorrelatedwiththemoleculestructureandthe recalcitrancewasincreasedfordyescontainingradicalssuch asnitroandsulphurgroups,asisthecaseforsulphurblack andRemazolBrilliantBlue.
Degradation of indigo dye by P. autumnale UTEX 1580 resulted in the formation of two metabolites, isatin and anthranilicacid,whichariseafterthedisappearanceofindigo
fromculturemediashowingthatthedegradationwas incom-plete. Toxicitydidnotincreasewiththeformationofthese metabolites,makingthetreatmentofindigobyP.autumnale UTEX1580aplausibletreatment.Themutagenicitytestwith Alliumcepaalsodidnotdemonstrateamutageniceffectafter theindigodegradation.
Thesemetaboliteswerenotdegradedduringtheperiodof assessmentbyP.autumnaleUTEX1580inapureculture. How-ever, these metabolitesare less complexthan the parental indigomoleculeandits degradationintheenvironmentby other microorganismsmayoccurmorereadily.Inatertiary treatment, the presence ofmixed algaepopulations might causetheremovalofthesemetabolitesinapossible sequen-tialdegradationprocessbyaconsortiumofalgaestrainsfor completedegradationoftheindigodye.
Thethreecyanobacteriastrainsevaluated,showed poten-tial to remediatetextile effluent and reducethe pollutant load. However, the cyanobacteriatreatment ofsludge was lessefficientthanfortheeffluent,probablyduetothehigh complexicityofthesludge.ThecyanobacteriumP.autumnale UTEX1580completelydegradedtheindigodyeintosecondary metabolites, which were nottoxic. Further studiesusing a mixedcultureofalgae,insteadofapureculture,shouldbe per-formedtoachievecompletedegradation.Algaecanbeusedfor removaloftoxicdyesinatertiarytreatmentusingfacultative lagoons,mainlytoimprovetheeffluentqualitywhenthese recalcitrant compounds are not removed in the secondary treatment.
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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s
1.CrippsC,BumpusJA,AustSD.Biodegradationofazoand heterocyclicdyesbyPhanerochaetechrysosporium.ApplEnviron Microbiol.1990;56:1114–1118.
2.PearceCJ,LloydJR,GuthrieJT.Theremovalofcolorfrom textilewaste-waterusingwholebacterialcells.Areview. DyesPigments.2003;58:179–186.
3.BaeJS,FreemanHS.Aquatictoxicityevaluationofnewdirect dyestotheDaphniamagna.DyesPigments.2007;73:81–85. 4.CoelhoMCLS,CoimbrãoCA,ValentGU,SatoMIZ,TargaH.
MutagenicityevaluationofindustrialeffluentbyAmesassay. EnvironMolMutagen.1992;19(S20):199–211.
5.UmbuzeiroGA,FreemanHS,WarrenSH,KummrowF, ClaxtonLD.Thecontributionofazodyestothemutagenic activityoftheCristaisRiver.Chemosphere.2005;60:55–64. 6.O’NeillC,HawkesFR,HawkesDL,Lourenc¸oND,Pinheiro
HM,DelleW.Colourintextileeffluents-sources,
measurement,dischargecontentsandstimulation:areview. JChemTechnolBiotechnol.1999;74:1009–1018.
7.RalanaponglekoK,PhetsomJ.Decolorizationbyconventional treatmentisinefficient.IntJChemEngAppl.2014;5:26–30. 8.JinqiL,HoutianL.Degradationofazodyesbyalgae.Environ
Pollut.1992;75:273–278.
9.ShahV,GargN,MadamwarD.Anintegratedprocessof textiledyeremovalandhydrogenevolutionusing cyanobacterium,Phormidiumvalderianum.WorldJMicrobiol Biotechnol.2001;17:499–504.
10.ParikhA,MadamwarD.Textiledyedecolorizationusing cyanobacteria.BiotechnolLett.2005;27:323–336.
11.OmarHH.Algaldecolorizationanddegradationofmonoazo anddiazodyes.PakJBiolSci.2008;11:1310–1316.
12.VyayakumarS,ManoharauC.Treatmentofdyeindustry effluentusingfreeandimmobilizedcyanobacteria.JBiorem Biodeg.2012;3:1–6.
13.HenciyaS,ShankarM,MaligaP.Decolorizationoftextiledye effluentbymarinecyanobacteriumLinghyasp.BDU9001 withcoirpith.IntJEnvironSci.2013;3:1909–1918.
14.MuraliS,HenciyaS,MaligaP.Bioremediationoftannery effluentusingfreshwatercyanobacteriumOscillatoriaannae withcoirpith.IntJEnvironSci.2013;3:1881–1890.
15.JaysudhaS,SampathkumarP.Nutrientremovalfrom tanneryeffluentbyfreeandimmobilizedcellsofmarine microalgaeChlorellasalina.IntJEnvironBiol.2014;4:21–26. 16.FioreMF,TrevorsJT.Cellcompositionandmetaltolerancein
cyanobacteria.Biometals.1994;7:83–103.
17.AllenMM,ArnonDI.Studiesonnitrogen-fixingblue-green algae.I–GrowthandnitrogenfixationbyAnabaenacylindrica Lemm.PlantPhysiol.1955;30:366–372.
18.AllenMB.Simpleconditionsforgrowthofunicellular blue-greenalgaeonplates.JApplPhycol.1968;4:1–4. 19.TrottierS,BlaiseC,KusinT,JohnsonEM.Acutetoxicity
assessmentofaqueoussamplesusingamicroplate-based Hydraattenuattaassay.TechMethods.1997;12:265–271. 20.BlaiseC,ForgetG,TrottierS.Toxicityscreeningofaqueous
samplesusingacost-effective72-HexposureSelenastrum capricornutumassay.TechMethods.2000;15:352–359.
21.DutkaB.Short-termrootelongationtoxicitybioassay.Methodsfor toxicologicalanalysisofwaters,wastewatersandsediments. Ontario:NationalWaterResearchInstitute,CCIW, EnvironmentCanada;1989.
22.FernandesTCC,MazzeoDEC,Marin-MoralesMA. Mechanismsofmicronucleiformationinpolyploidizated cellsofAlliumcepaexposedtotrifluralinherbicide.Pestic BiochemPhysiol.2007;88:252–259.
23.CamposR,KandelbauerA,RobraKHA,Cavaco-PauloA, GübitzGM.Indigodegradationwithpurifiedlaccasesfrom TrameteshirsutaandSclerotiumrolfsii.JBiotechnol.
2001;89:131–139.
24.KhannaN,SharmaS.Alliumceparootchromosomal aberrationassay:areview.IndianJPharmBiolRes. 2013;1:105–119.
25.Silva-StenicoME,VieiraFDP,GenuárioDB,SilvaCSP,Moraes LAB,FioreMF.Decolorizationoftextiledyesby
cyanobacteria.JBrazChemSoc.2012;23:1863–1870.
26.QueirozBPV,StefanelliT.BiodegradationdecorantesTêxteis porAnabaenaflos-aquae.EngAmb.2011;8:026–035.
27.NguyenTA,JuangRS.Treatmentofwatersandwastewaters containingsulfurdyes:areview.ChemEngJ.
2013;219:109–117.
28.PadmanabanVC,PrakashSS,SherildarP,JacobJP, NelliparambilK.Biodegradationofantraquinonebased compounds:review.IntJAdvResEngTechnol.2013;4:74–83.
