Biotehnološki procesi uzgoja termofilne bakterije Bacillus smithii DSM 460 na različitim temperaturama te istraživanje inhibitornog utjecaja mravlje i octene kiseline

master's thesis

• Title (english): Biotechnological processes for cultivation of the thermophilic bacterium Bacillus smithii DSM 460 at different temperatures and investigation of the inhibitory effect of formic and acetic acid
• Author: Lucija Vekić
• Mentor: Mario Novak (mentor)
• Committee member: Božidar Šantek (predsjednik povjerenstva)
• Committee member: Andreja Leboš-Pavunc (član povjerenstva)
• Committee member: Blaženka Kos (član povjerenstva)
• 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: 2022-09-21, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Proizvodnja zelenih kemikalija iz lignoceluloznih sirovina istražuje se kao alternativa proizvodnji kemikalija iz naftnih derivata. Mliječna kiselina pripada skupini zelenih kemikalija te je zbog svojih brojnih primjena važan biotehnološki proizvod. Mliječnu kiselinu sintetizira i bakterija Bacillus smithii DSM 460 koja je služila kao proizvodni mikroorganizam u ovom istraživanju. Provedena su istraživanja u kojima je ova bakterija uzgojena na kemijski definiranim podlogama različitih sastava (glukoza i/ili ksiloza) pri različitim temperaturama (40, 50 i 60 °C). Osim toga proveden je i uzgoj na detoksiciranom hidrolizatu otpadnog pivskog tropa u bioreaktoru, koji je rezultirao niskim procesnim parametrima te uzgoji s dodatkom mravlje i octene kiseline kao inhibitora. Optimalna temperatura za uzgoj B. smithii DSM 460 i proizvodnju mliječne kiseline bila je 50 °C pri kojoj je postignut prinos mliječne kiseline 7,593 g Lˉ¹ te produktivnost 0,262 g Lˉ¹ hˉ¹. Pri 60 °C dobivene su nešto niže vrijednosti procesnih parametara, a pri 40 °C su prinosi i produktivnost bili vrlo niski. Dodatak mravlje i octene kiseline u nižim koncentracijama nije utjecao na rast B. smithii DSM 460 te na sintezu mliječne kiseline, no pri višim koncentracijama je došlo do potpune inhibicije.

Abstract (english)

Production of green chemicals from lignocellulosic biomass is being investigated as an alternative to the production of chemicals from petroleum derivates. Lactic acid belongs to the group of green chemicals and is an important biotechnological product due to its numerous applications. One of the producers of lactic acid is Bacillus smithii DSM 460, which was used for this study. This bacterium was grown on chemically defined media of various composition (glucose and/or xylose) at different temperatures (40, 50 and 60 °C). In addition, cultivation was carried out on detoxified hydrolyzate of waste beer wort in bioreactor with stirrer, which resulted in low process parameters, and cultivation with addition of formic and acetic acid as inhibitors. Optimal temperature for the cultivation of B. smithii DSM 460 and the production of lactic acid was 50 °C. At that temperature yield of lactic acid was stated at 7.593 g Lˉ¹ and productivity at 0.262 g Lˉ¹ hˉ¹. Slightly lower values of process parameters were obtained at 60 °C while yields and productivity at 40 °C were very low. Addition of formic and acetic acid at lower concentrations to the media did not affect the growth of B. smithii DSM 460 and the production of lactic acid, while higher concentrations resulted in complete inhibition.

• Keywords: Bacillus smithii DSM 460; mliječna kiselina; termofil; lignocelulozne sirovine; inhibicija
• Keywords (english): Bacillus smithii DSM 460; lactic acid; thermophil; lignocellulosic biomass; inhibition
• Language: croatian
• URN:NBN: urn:nbn:hr:159:452404
• 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: 2023-03-01 13:08:49