Ekstrakcija in karakterizacija fikobiliproteinov iz mikroalg vrste Arthrospira platensis pred in po mlečnokislinski fermentaciji

Pagon, Ana (author), Jamnik, Polona (mentor)

Fikobiliproteini so pigmentni proteini, ki v mikroalgah vrste Arthrospira platensis sodelujejo pri absorpciji svetlobe za fotosintezo. Glede na spekter absorpcije ločimo tri predstavnike: fikoeritrin, fikocianin in alofikocianin. Ker z mlečnokislinsko fermentacijo substrata lahko vplivamo na profil in aktivnost bioaktivnih komponent v njem, smo v nalogi preverili vpliv mlečnokislinske fermentacije na čistost fikobiliproteinov in njihovo antioksidativno aktivnost in vitro ter in vivo. Biomaso mikroalge smo fermentirali z bakterijami vrste Lactobacillus plantarum. Ekstrakte fermentirane in nefermentirane biomase smo pripravili po dveh različnih metodah ekstrakcije, mehanski in nemehanski. Fikobiliproteine v ekstraktih smo dodatno očistili z dvostopenjskim obarjanjem z amonijevim sulfatom. Vpliv mlečnokislinske fermentacije smo preverjali tako v ekstraktih kot pri oborjenih fikobiliproteinih. Pri nemehanski metodi nismo zaznali razlik med faktorji čistosti fikobiliproteinov v ekstraktih fermentirane in nefermentirane mikroalge, medtem ko smo pri oborjenih fikobiliproteinih pri vseh predstavnikih dosegli višji faktor čistosti pri fermentirani mikroalgi v primerjavi z nefermentirano. Antioksidativna aktivnost in vitro oborjenih fikobiliproteinov fermentirane mikroalge je bila višja v primerjavi z nefermentirano mikroalgo. Pri antioksidativni aktivnosti ekstraktov ni bilo razlik med fermentirano in nefermentirano mikroalgo. Antioksidativna aktivnost in vivo oborjenih fikobiliproteinov fermentirane in nefermentirane mikroalge se v dani koncentraciji glede na kontrolo ni razlikovala. Pri mehanski metodi ekstrakcije niti pri ekstraktih niti pri oborjenih fikobiliproteinih nismo določili razlik med faktorji čistosti fermentirane in nefermentirane mikroalge. Antioksidativna aktivnost in vitro ekstraktov in oborjenih fikobiliproteinov se med fermentirano in nefermentirano mikroalgo ni razlikovala. Tudi pri mehanski metodi se antioksidativna aktivnost in vivo oborjenih fikobiliproteinov fermentirane in nefermentirane mikroalge v dani koncentraciji glede na kontrolo ni razlikovala.

• Language: Slovenian
• Keywords: mikroalge, spirulina, pigmentni proteini, fikobiliproteini, mlečnokislinska fermentacija, ekstrakcija, čistost proteinov, antioksidativna aktivnost
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [A. Pagon]
• Year: 2020
• PID: 20.500.12556/RUL-116568
• UDC: 582.232:665.939.35
• COBISS.SI-ID: 17966851
• Publication date in RUL: 28.05.2020

Secondary language

• Language: English
• Title: Extraction and characterization of phycobiliproteins from microalgae Arthrospira platensis before and after lactic acid fermentation

Abstract

Phycobiliproteins are light harvesting pigment proteins involved in light absorption during photosynthesis in microalgae Arthrospira platensis. According to their absorbance spectrum we distinguish between three representatives: phycoerythrin, phycocyanin and allophycocyanin. Since the lactic fermentation of a substrate can affect the profile and activity of its bioactive components, we investigated the effect of lactic fermentation on purity ratio and antioxidant activity of phycobiliproteins in vitro and in vivo. Lactobacillus plantarum was used for fermentation of microalgal biomass. The extracts of fermented and nonfermented biomass were prepared by two different extraction methods; mechanic and nonmechanic. Phycobiliproteins in extracts were further purified by two-phased ammonium sulphate precipitation. Analysis were performed both on extracts and precipitated phycobiliproteins. Results of nonmechanic extraction method did not show differences in purity ratio of phycobiliproteins between the extracts of fermented and nonfermented microalgae, whereas in precipitated phycobiliproteins purity ratio of all representatives obtained from fermented microalgae were higher compared to the nonfermented microalgae. After fermentation the in vitro antioxidant activity of precipitated phycobiliproteins was higher compared to precipitated phycobiliproteins before fermentation. The antioxidant activity in vitro of extracts did not differ between fermented and nonfermented microalgae. The in vivo antioxidant activity at given concentration did not differ between precipitated phycobiliproteins from fermented and nonfermented microalgae compared to controls. With mechanic extraction method neither extracts nor precipitated phycobiliproteins differed in purity ratio of fermented and nonfermented microalgae. Moreover, the in vitro antioxidant activity of microalgae extracts and precipitated phycobiliproteins did not differ between fermented and nonfermented microalgae, as well as the in vivo antioxidant activity at a given concentration did not differ between precipitated phycobiliproteins from fermented and nonfermented microalgae compared to controls.

• Keywords: microalgae, spirulina, pigment proteins, phycobiliproteins, lactic fermentation, extraction, purity of proteins, antioxidative activity