Proizvodnja mliječne kiseline iz hidrolizata lignoceluloznih sirovina i utjecaj furfurala na rast i aktivnost bakterija mliječne kiseline

master's thesis

• Title (english): Lactic acid production from lignocellulosic hydrolysates and influence of furfural on growth and activity of lactic acid bacteria
• Author: Alen Kostić
• Mentor: Božidar Šantek (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: 2016-09-28, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Mliječna kiselina može se proizvesti fermentacijom jednostavnih ugljikohidrata (mono- i disaharida), polimernih ugljikohidrata (škrob, celuloza) ili sirovina koje sadrže navedene ugljikohidrate (npr. šećerna repa, kukuruzna krupica, pšenična krupica, kukuruzovina, pšenična slama). U ovom radu provedeni su uzgoji bakterija mliječne kiseline L. amylovorus DSM 20531T i L. coryniformis subsp. torquens DSM 20004T u modificiranoj MRS podlozi koja kao glavni izvor ugljika sadrži tri jednostavna ugljikohidrata: glukozu, ksilozu i arabinozu. Provedeni su i uzgoji ovih bakterija na hidrolizatima lignoceluloznih sirovina (kukuruzovine, kukuruznih oklasaka i pšenične slame) dobivenih nakon predobrade s 1,0 %-tnom i 0,5 %-tnom sumpornom kiselinom u visokotlačnom reaktoru (vrijeme zadržavanja 5 min). Mliječna kiselina proizvedena je tijekom uzgoja ovih bakterija iz hidrolizata kukuruzovine i pšenične slame dobivenih nakon predobrade s 0,5 % sumpornom kiselinom u visokotlačnom reaktoru. Bioprocesi su provedeni pri temperaturi od 40 °C, brzini okretaja miješala od 150 u minuti i bez regulacije pH vrijednosti. Bakterija L. amylovorus DSM 20531T odabrana je za provođenje bioprocesa u horizontalnom rotirajućem cijevnom bioreaktoru na hidrolizatima pšenične slame i kukuruzovine zbog većeg prinosa mliječne kiseline u odnosu na L. coryniformis subsp. torquens DSM 20004T. Zbog prisutnosti različitih toksičnih spojeva u hidrolizatima lignoceluloznih sirovina određen je i utjecaj različitih koncentracija furfurala (100–5000 mg L-1) na rast i aktivnost bakterije L. amylovorus DSM 20531T u MRS podlozi.

Abstract (english)

Lactic acid can be produced by fermentation of simpler carbohydrates (mono- and disaccharides), polymeric carbohydrates (starch, cellulose) or raw materials that contain these carbohydrates (e.g. sugar beet, corn grits, wheat grits, corn stover, wheat straw). In this work, fermentations in modified MRS medium that has three carbohydrates (glucose, xylose and arabinose) as main carbon source, were conducted by lactic acid bacteria L. amylovorus DSM 20531T and L. coryniformis subsp. torquens DSM 20004T. The bacteria were also used for fermentations of hydrolysates of lignocellulosic raw materials (corn stover, corn cob and wheat straw). The hydrolysates were obtained after pretreatment with 1.0% and 0.5% sulfuric acid in high pressure reactor with residence time of 5 minutes. Lactic acid was produced from hydrolysates that were obtained after pretreatment with 0.5% sulfuric acid. Bioprocesses were performed at 40°C, stirrer speed of 150 min-1, and without pH regulation. Bacterium L. amylovorus DSM 20531T was chosen for conducting fermentations in horizontal rotating tubular bioreactor on corn stover and wheat straw hydrolysates due to higher lactic acid yield than L. coryniformis subsp. torquens DSM 20004T. Lignocellulosic hydrolysates have different toxic compounds present in the medium. Therefore, influence of different concentrations of furfural (100–5000 mg L-1) on growth and activity of L. amylovorus DSM 20531T in MRS medium was determined.

• Keywords: bakterije mliječne kiseline; lignocelulozne sirovine; fermentacija; mliječna kiselina; inhibitori
• Keywords (english): lactic acid bacteria; lignocellulose raw material; fermentation; lactic acid; inhibitors
• Language: croatian
• URN:NBN: urn:nbn:hr:159:668655
• Study programme: Title: Bioprocess Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva (magistar/magistra inženjer/inženjerka bioprocesnog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-04-25 07:29:06