Bakteriocino geobacilino 19 heterologinė biosintezė /

• Main Author: Šablevičiūtė, Dovilė
• Format: Master Thesis
• Language: Lithuanian; English
• Published: Institutional Repository of Vilnius University 2022
• Subjects: Arctic
• Online Access: https://repository.vu.lt/VU:ELABAETD192964668&prefLang=en_US

HETEROLOGOUS BIOSYNTHESIS OF BACTERIOCIN GEOBACILLIN 19 Bacteriocins are antimicrobial proteins synthesised by ribosomes, many of which are known as antimicrobial peptides because of their small size. Bacteriocins have an inhibitory effect against micro-organisms of the same species or against micro-organisms of a different species or genus. Detailed research and understanding about the mechanisms of action of these antimicrobials is important for their application in medicine, cancer treatment and the food industry. Although the information is rapidly increasing, very little research has been carried out on bacteriocins produced by thermophilic bacteria. New data in this field may lead to the application of thermostable bacteriocins produced by thermophilic bacteria in biotechnology and industry. The strain used in this study is Geobacillus stearothermophilus 15, which was previously isolated from oil fields in Lithuania. This strain produces two bacteriocins, geobacillin 26 (Geo26), which has a molecular mass of 26 kDa, and geobacillin 19 (Geo19), which has a molecular mass of 19 kDa. In this work, the studies on geobacillin 19 were described. The aim of this work is to heterologously synthesise the active Geo19. First, heterologous biosynthesis was tested in Escherichia coli cells. In order to synthesize an active bacteriocin, different variants were tested using the Geo19 precursor with and without a signal peptide, as well as gene expression co-expressed with the E. coli secretory signal peptide pelB. Gene expression is carried out in concert with genes encoding Geo19 biosynthesis. Gene fusion is carried out in different E. coli expression strains: Rosetta (DE3), C41 (DE3) and Arctic Express (DE3). It was found that the synthesis of the Geo19 precursor without the signal peptide leads to the synthesis of a higher amount of bacteriocin, but that it is not active, and that the production of active Geo19 is not affected by the pelB signal sequence. As no active bacteriocin could be synthesised in E. coli ...