Desa, Shakinaz

Kusnan, Misri

Omar, Hishamuddin

Omar, Ismail

Shamaan, Nor Aripin

Universiti Putra Malaysia Institutional Repository

Biological SciencesDevelopment of Herbicide Detection Method Using Mlcroalgae as a BiosensorNor Arlpln 5hamaan. 5haklnaz Desa. 'Hlshamuddln Omar. "Mlerl Kuenan. and lemall OmarFaculty of Science and Environmental studiesUniversiti Putra Malaysia43400 UPM. Serdang. SelangorMalaysiaE-mail ofCorrespondingAuthor:narjpjn@fsas.upm.edu.myKey words: Chlorella vlIlgaris. biological indicator toxicity evaluation chl h II f1 ', , orop y uorescence, oxygen production.IntroductionThe microalgae, Chlorella vulgaris hasbeen reported to be a sensitive indica-tor for photosystem II inhibitors. Testsusing the microalgac revealed thatchlorophyll fluorescence greatly in-creases in the presence of photosystemII inhibitors in the media. Based on thisstudy, we investigated the microalgaeobtained locally i.e. Chlorella vulgaris.Scenedesmus quadrlqauda and Chloro-coccum spp and used them in toxicityevaluations of photosystern II inhibi-tors. The three species of microalgaewere isolated. purified and cultured inthe laboratory. Evaluations of the tox-icity of the herbicides atrazine, si-ma7.ine and diuron were carried out bychlorophyll fluorescence and meas-urement of the rate of oxygen producedduring photosynthesis.Materials and MethodsThe microalgac Chiarella vulgaris.Scenedesmus quadriqauda and Chloro-caecum spp were first isolated from theHulu Pangsoon water reservoir and apond in Universiti Putra Malaysia.respectively. The microalagae werepurified and cultured in the laboratoryunder optimised conditions for growth.The cells were determined for chloro-phyll content. cell density. growth rate.optimum Iight:dark cycles. temperatureand light intensity. Once the parame·ters were optimised. culture of the mi-croalgae was initiated. For measure-ment of photosynthesis. determinationof chlorophyll fluorescence in free cellsand rate of oxygen produced were car·ried out. Photosystem II inhibitorsused were atrazine. simazine and diu-ron. The herbicides were added to theculture media and chlorophyll fluores·cence and rate of oxygen productionwere determined. Free Chiarella vul·garis were then immobilized in algi-nate beads of 2 mm diameter. Condi-tions for Ihe formation of Ihe microla-gae in spherical beads were optimi7.c:d.Free and immobilized Chlorella vul-garis were subjected to herbicide tox-icity evaluations by measuring the rateof oxygen released during photosyn-thesis.Results and DiscussionOf the three microalgae isolated andcultured in the laboratory. Chlorellavulgaris exhibited the best growth rate.chlorophyll content/cell and chloro-phyll fluorescence compared withScenedesmus quadriqauda and Chloro-coccum spp .• respectively. Chlorellavulgaris was found to be more sensi-tive to the herbicides atrazine, simazineand diuron than the other microlagespecies. Chlorophyll fluorescence ofChlorella vulgaris in the presence ofthe herbicides were significantly in-creased and from a mathematical for-mula derived from the results obtained.it is possible to extrapolate and deter-mine the minimum concentration ofherbicide required to inhibit photosyn-thesis.Due to technical problems associatedwith the free-living nature of Chlorellavulgaris. an attempt was made to im-mobilize the cells so that a much easierand rapid method can be used to de-termine the change in the r.lle of photo·synthesis. Round spherical alginatebeads of 2 mm diameter were formedwith varying concentrations ofChlorella vulgaris trapped in the beadswere produced. Since the cells wereentrapped in beads. chlorophyll fluo-rescence could not be determined.Thus. the oxygen electrode wa.~ used todetermine quantitatively the rate ofoxygen released during photosynthesis.A comparison wa~ carried out betweenfree cells. a standard concentration oftrapped cells and varying concentra·tions of trapped cells in alginate beadswith respect to herbicide toxicity andrate of photosynthesis. The trappedcells all exhibited a lower rale of oxy·gen relea.~ compared with the freeResearch funded by the Intensification of Re~in Priority area., (IRPA) - Supported by IRPA RM·7(1996-2000). Cycle 1997. Granl Q9..04-02-00S4.cells. For herbicide toxicity evalua-tions, the trapped cells also e"hibitc:d IIlower rate of ox ygen re leased thun freecells and control cells.ConclusionsMeasurement of herbicide toxicity ismost useful using free Chlorella vul·garls by chlorophyll fluorescence. It iKnot recommended to use immobilizedcells for the determination of herbicidetoxicity using the oxygen electrode.Benefits from the studyA cheap and easy method for deter-mining contumination of wuter by her-bicide using free Chlorellu vulguris andchlorophyll fluorescence has been de-veloped. The method for encapsulationof the microalgae Chlorella vulKaris inalginate beads ha.~been optimized. Thetrapped cells have potential uses.Literature cited in the textNone.Project Publications InRefereed JournalsShamBlIn.N.A,.I>Csa. S.. Omar. I.• Kusnan,M. and Omar. H. 2000. Freshwaler algaea5 a biological marker. I·The selection ofChlorella vulgarl" U B telil organism forherbicide toxicity uliing chlorophyllOuoreliCence.Mula,v,flan J. Blm·h,m.Mol". Bioi. 5: 10·13Shamuan. N,A.. Deia. S.. Omar. I,. Ku.nnn.M. and Gmar. H. 20()O. Freshwater algaeas a biological marker. 2· Suitability ofChlo"lIa vulgaris 81 II lell organism forthe toxicity of pholO~y~lemII herbicide.using chlorophyll Ouore.cence.Mtlla,Vslan J. Bltl('hrm. Molt'c. Bioi. ,:14·17Graduate ResearchShakina1-Desu, 2()()2. Biochemi~try (PhD).Univeniti Putra MalaY5ia.Shakina~ Desa, 1997. Riochemi5lrY(MS).Univeniti PUlraMalay.ia.231

Development of herbicide detection method using microalgae as a biosensor

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Development of herbicide detection method using microalgae as a biosensor

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