Kvantitativno in kvalitativno določanje cianobakterij v vodnem telesu z uporabo svetlobe različnih valovnih dolžin

Rozina, Tinkara (avtor), Eleršek, Tina (mentor), Leštan, Domen (komentor)

Cvetenje cianobakterij predstavlja izjemno tveganje za okolje, tako za ekosistem kot za sesalce. Njihovo zgodnje odkrivanje in nadzorovanje je zato ključnega pomena za upravljanje z vodnimi telesi. Standardne metode spremljanja fitoplanktona imajo številne omejitve, zato je potrebna nadgradnja z metodami, ki dajejo rezultate v realnem času. Metoda, ki omogoča takojšnjo detekcijo in kvantifikacijo cianobakterij in ostalega fitoplanktona je merjenje fluorescence fotosintetskih pigmentov. Z meritvami fluorescence fikocianina (PC) in klorofila a (CHL) pa lahko ob poznani biomasi cianobakterij zaznamo tudi stres oziroma spremembe fiziološkega stanja cianobakterij. Senzorje smo najprej uporabili na akseničnih laboratorijskih kulturah alg in cianobakterij, z meritvami smo nadaljevali na naravnih vzorcih na Koseškem bajerju, ribniku v Hotinji vasi in Blejskemu jezeru. Ugotovili smo, da je odvisnost med fluorescenco PC in CHL ter standardnima metodama kvantifikacije fitoplanktona (določanjem biovolumna in ekstrakcijo CHL in PC) linearno z visokimi korelacijskimi koeficienti. Tudi meritve fluorescence CHL na Koseškem bajerju so pokazale visoke korelacije z biovolumnom fitoplanktona skozi celotno dvoletno obdobje izvajanja meritev kljub spremembam v vrstni sestavi. V drugem delu smo analizirali celične spremembe povzročene z elektrokemijsko obdelavo (z borom dopirano diamantno elektrodo), ki so se odražale tudi v prehodnem povečanje fluorescence PC in manj izrazito povečanju fluorescence CHL. Signal CHL doseže vrh 6 ur, signal PC pa 10 ur, po izzvani poškodbi. Spremeni se tudi razmerje med fluorescenco PC in CHL. Na podlagi rezultatov meritev ocenjujejmo, da je kombinacija CHL in PC senzorja optimalna za ugotavljanje prisotnosti bakterioplanktona. Ta sistem omogoča kvantitativno in kvalitativno zaznavanje fitoplanktona v vodnem telesu in prispeva tako k znanstvenemu (razvoj metode za bolj natančno zgodnje odkrivanje cianobakterijskega tveganja v realnem času) kot k aplikativnemu vidiku (sistem za preventivno spremljanje in zgodnje opozarjanje na cianobakterijsko tveganje v okviru okolijskega monitoringa ter potencial za zmanjšanje škodljivih učinkov cianobakterij ob njihovem prekomernem razmnoževanju).

• Jezik: Slovenski jezik
• Ključne besede: Cianobakterije, Microcystis aeruginosa, zelene alge, fluorescenca, klorofil a, fikocianin, cianotoksini, elektrokemijska oksidacija
• Vrsta gradiva: Doktorsko delo/naloga
• Organizacija: FGG - Fakulteta za gradbeništvo in geodezijo
• Leto izida: 2019
• PID: 20.500.12556/RUL-106568
• Datum objave v RUL: 06.03.2019

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Quantitative and qualitative determination of cyanobacteria in water bodies using different wavelenghts of light

Izvleček

Cyanobacterial blooming represents an extreme risk for the environment, for ecocystems and mammals. Its early detection is thus of key importance in water management. Standard methods of phytoplankton monitoring come with numerous limitations, therefore upgrades are needed that will give results in real time. One method that enables immediate detection and quantification of cyanobacteria and other phytoplankton, is the measurement of fluorescence of photosynthesis pigments. When biomass is known, measurements of phycocyanin (PC) and chlorophyll (CHL) fluorescence can also detect the stress, or changes to the physiological state, of cyanobacteria. Our sensors were first used on axenic laboratory algae and cyanobacteria cultures, and then samples from the Koseze Pond, the Hotinja vas Pond and Lake Bled. It was discovered that the relationship between the PC- and CHL fluorescence, and standard methods of phytoplankton quantification (determining the biovolume and CHL extraction), is linear. The correlation coefficients between standard methods and PC- and CHL fluorescence were very high. Measurements of CHL fluorescence at the Koseze Pond showed high correlations with the phytoplankton biovolume throughout the entire two-year measurement period, even though the species composition was significantly altered. In stage two, we analized the cellular changes, induced by electrochemical treatment (with boron doped diamond electrodes), which were characterized by transitionally increased PC- and, less obviously, CHL fluorescence. The CHL signal reaches its peak value 6 hours after the induced damage, and the PC signal after 10 hours. Furthermore, the change in the ratio between PC- and CHL fluorescence is observed. On the basis of the results of our measurements, we believe that the CHL- and PC sensor combination is an optimal solution for determining the presence of the bacterioplankton. The system enables quantitative and qualitative detection of phytoplankton in a body of water, and thus coordinated application of measures, developed to reduce the detrimental effects of cyanobacteria in the case of excessive reproduction.

• Ključne besede: Cyanobacteria, Microcystis aeruginosa, green algae, fluorescence, chlorophyll a, phycocyanin, cyanotoxins, electrochemical oxidation