Ekstracelularne proteinaze bakterijskih sojeva iz Lactobacillus i Lactococcus rodova s kazeinolitičkim djelovanjem

undergraduate thesis

• Title (english): Extracellular proteases of bacterial strains from Lactobacillus and Lactococcus genera with caseinolytic activities
• Author: Helena Rak
• Mentor: Jasna Novak (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for Antibiotic, Enzyme, Probiotic and Starter Cultures Technology); Zagreb
• Defense date and country: 2021-06-17, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Proteinaze probiotičkih bakterija mliječne kiseline (BMK), osim što osiguravaju bakterijskim stanicama izvore dušika i aminokiselina esencijalnih za stanični rast, kataliziraju i razgradnju kazeina iz fermentiranih mliječnih proizvoda do peptida koji mogu imati bioaktivne učinke. Za detekciju potencijalnih producenta proteinaza, u ovom radu su korišteni sojevi iz rodova Lactobacillus i Lactococcus kod kojih je ustanovljen Fmc⁺ fenotip, koji se povezuje s prisutnošću proteinaza. Analizom fenotipa hidrolize kazeina analiziranih BMK prilikom inkubacije supernatanta kulture ili koncentrirane biomase stanica u diferencijalnoj hranjivoj podlozi, sojevi Lactobacillus brevis D6 i Lactobacillus plantarum D13 nakon uzgoja u optimalnoj hranjivoj podlozi za rast, a sojevi Lactococcus lactis ZG5-32 i Lactobacillus brevis SF9B nakon uzgoja u obranom mlijeku iskazali su značajnije kazeinolitičko djelovanje koje može rezultirati sintezom biopeptida. Optimiran je protokol za ekstrakciju proteinaza iz odabranih sojeva BMK te su proteinski uzorci analizirani SDS-PAGE metodom. Proteinski ekstrakti djelomično purificirane proteinaze sojeva Lc. lactis ZG5-32 i ZG7-10 su i u vrlo niskim koncentracijama zadržali proteolitičku aktivnost. SDS-PAGE metodom detektirani su proteini u ekstraktu sojeva Lb. brevis D6 i SF9B, Lb. fermentum D12 i Lb. plantarum D13 čiju je daljnju karakterizaciju potrebno provesti.

Abstract (english)

In addition to providing bacterial cells with nitrogen sources and amino acids essential for cell growth, certain probiotic lactic acid bacterial proteinases also catalyze the breakdown of casein from fermented dairy products to peptides with potential bioactive effects. Lactobacillus and Lactococcus strains showing the Fmc⁺ phenotype were analysed for the presence of proteases. Analysis of casein hydrolysis phenotype of LAB, during incubation of culture supernatant or concentrated cell biomass, in differential nutrient medium showed that Lactobacillus brevis D6 and Lactobacillus plantarum D13 strains after growth in the optimal growth medium, showed a significant caseinolytic effect, whereas the same was observed for Lactococcus lactis ZG5-32 and Lactobacillus brevis SF9B strains after growth in skim milk. The proteinases extraction was optimized and protein samples were analyzed by SDS-PAGE method. Protein extracts of partially purified proteinase of strains Lc. lactis ZG5-32 and ZG7-10, retained proteolytic activity even at very low concentrations. Proteins in the extract of strains: Lb. brevis D6 and SF9B, Lb. fermentum D12 and Lb. plantarum D13 were detected by the SDS-PAGE method and their identification must be performed.

• Keywords: biopeptidi; Fmc⁺ fenotip; Lactobacillus; Lactococcus; proteinaze; proteolitički sustav
• Keywords (english): biopeptides; Fmc⁺ phenotype; Lactobacillus; Lactococcus; proteinase; proteolytic system
• Language: croatian
• URN:NBN: urn:nbn:hr:159:838917
• Study programme: Title: Biotechnology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka biotehnologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka biotehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-06-17 12:43:57