Proizvodnja optički čiste mliječne kiseline s pomoću bakterije Lactobacillus gasseri JCM 1131T

master's thesis

• Title (english): Production of optically pure lactic acid by bacterium Lactobacillus gasseri JCM 1131T
• Author: Juliana Lana Prah
• Mentor: Antonija Trontel (mentor)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for Biochemical Engineering, Industrial Microbiology and Malting and Brewing Technology); Zagreb
• Defense date and country: 2019-02-28, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

U ovom radu proveden je uzgoj divljeg tipa bakterije Lactobacillus gasseri JCM 1131T koji proizvodi oba stereoizomera mliječne kiseline, L-(+)- i D-(-)-mliječnu kiselinu, u MRS podlozi s relativno niskom (20 g L-1) i visokom početnom koncentracijom glukoze (80 g L-1) kako bi se utvrdilo postoji li značajna inhibicija supstratom tijekom uzgoja šaržnim postupkom u bioreaktoru s miješalom. Zatim su provedeni uzgoji dva genetski modificirana soja ove bakterije koji mogu proizvoditi samo jedan stereoizomer mliječne kiseline, L-(+)-mliječnu kiselinu (L. gasseri Hi 41/3/2) i D-(-)-mliječnu kiselinu (L. gasseri Hi 26/13/10) u MRS podlozi (20 g L-1). Izračunati osnovni biokinetički i procesni parametri korišteni su za određivanje uspješnosti provedenih bioprocesa te su dobivene vrijednosti uspoređene s vrijednostima dobivenim za divlji tip bakterije L. gasseri JCM 1131T (PrP, JCM 1131 T = 0,66 g L-1 h-1; PrP, Hi 26/13/10 = 0,66 g L-1 h-1; PrP, Hi 41/3/2 = 0,63 g L-1 h-1). Zatim su provedeni bioprocesi odvojene hidrolize alkalno predobrađene pšenične slame s celulazama i fermentacije dobivenih ugljikohidrata u modificiranoj MRS podlozi do mliječne kiseline s pomoću dva genetski modificirana soja bakterije L. gasseri, te je određena uspješnost procesa proizvodnje oba stereoizomera mliječne kiseline na hidrolizatu lignoceluloznih sirovina (PrP, Hi 41/3/2 = 0,83 g L-1 h-1; PrP, Hi 26/13/10 = 0,75 g L-1 h-1).

Abstract (english)

Bacterium Lactobacillus gasseri JCM 1131T that produces both lactic acid stereoisomers, L-(+)- and D-(-)-lactic acid, in MRS substrate with relatively low (20 g L - 1) and high initial glucose concentration (80 g L-1) was used to determine whether there is significant substrate inhibition during batch processing in a stirred tank bioreactor. Afterwards, two genetically engineered strains of this bacterium that can produce only one lactic acid stereoisomer, L-(+)-lactic acid (L. gasseri Hi 41/3/2) and D-(-)-lactic acid (L. gasseri Hi 26/13/10) in MRS medium (20 g L-1) were used for fermentation. Certain biokinetic and process parameters were calculated from obtained data and used to determine the efficiency of these bioprocesses and compared to the values obtained for the wild type L. gasseri bacterium (PrP, JCM 1131 T = 0,66 g L-1 h-1; PrP, Hi 26/13/10 = 0,66 g L-1 h-1; PrP, Hi 41/3/2 = 0,63 g L-1 h-1). Separate hydrolysis processes of alkali-pretreated wheat straw with cellulases and fermentation of the obtained carbohydrates in modified MRS medium to lactic acid, using two genetically modified strains of L. gasseri bacterium were also performed. Efficiency of the separate hydrolysis and fermentation to specific lactic acid stereoisomer on lignocellulosic raw materials were determined (PrP, Hi 41/3/2 = 0,83 g L-1 h-1; PrP, Hi 26/13/10 = 0,75 g L-1 h-1).

• Keywords: optički čista mliječna kiselina; Lactobacillus gasseri; predobrađena pšenična slama; enzimska hidroliza
• Keywords (english): optically pure lactic acid; Lactobacillus gasseri; pretreated wheat straw; enzimatic hydrolysis
• Language: croatian
• URN:NBN: urn:nbn:hr:159:533816
• Study programme: Title: Molecular Biotechnology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka molekularne biotehnologije (magistar/magistra inženjer/inženjerka molekularne biotehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2019-12-06 12:47:57