Optimization of O-demethylation of low molecular weight compounds from lignin fractions

master's thesis

• Title (croatian): Optimiranje O-demetilacije niskomolekulskih spojeva nastalih frakcioniranjem lignina
• Author: Lidija Božić
• Mentor: Anita Slavica (mentor)
• Committee member: Renata Teparic (predsjednik 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: 2023-07-11, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology

Abstract

Optimal O-demethylation of guaiacol to catechol by unspecific peroxygenase 12 (UPO12) were obtained at 20 °C and pH of 6.0. The reaction follows Michaelis-Menten kinetics and Vₘₐₓ and Kₘ were determined (106.87 µmol/(L*min) and 8.29 µmol/(L*min), respectively). The initial co-substrate concentration higher than 10 mM reduces initial rate of the guaiacol consumption. Additional six UPO enzymes were considered for possible industrially relevant O-demethylation in batch and fed batch mode, and the best catechol producers were UPO12, UPO22, and UPO67. Immobilization success of UPO12 was lower than 50.0 %. Disproportional utilization of guaiacol and production of catechol occurs due to oxidation and dimerization of the substrate. The most encouraging fed batch conversions were obtained with initial concentration of the UPO12 of 0.05 µM, the guaiacol and H₂O₂ of 0.6 mM and with addition of all three components of the reaction mixture every 60 min in the same concentration over 6 h.

Abstract (croatian)

Optimalna O-demetilacija gvajakola u katehol pomoću nespecifične peroksigenaze 12 (UPO12) provedena je pri 20 °C i pH 6.0. Ova reakcija prati Michaelis-Menten kinetiku i određeni su Vₘₐₓ i Kₘ (redom, 106,87 µmol/(L*min) i 8,29 µmol/(L*min)). Početna koncentracija ko-supstrata veća od 10 mM reducira početnu brzinu potrošnje gvajakola. Dodatnih šest UPO enzima istraženo je za industrijski relevantnu O-demetilaciju supstrata batch i fed batch postupkom i najbolji proizvođači katehola su bili UPO12, UPO22, i UPO67. Uspješnost imobilizacije UPO12 bila je manja od 50.0 %. Neproporcionalna potrošnja gvajakola i proizvodnja katehola javlja se zbog oksidacije i dimerizacije ovog supstrata. Najučinkovitija fed batch konverzija postignuta je uz početnu koncentraciju UPO12 od 0,05 µM, gvajakola i H₂O₂ od 0,6 mM i uz dodatak svih triju komponenti reakcijske smjese svakih 60 min u istovjetnim koncentracijama kroz 6 h.

• Keywords: unspecific peroxygenase; UPO; O-demethylation; lignin; guaiacol
• Keywords (croatian): nespecifična peroksigenaza; UPO; O-demetilacija; lignin; gvajakol
• Language: english
• URN:NBN: urn:nbn:hr:159:708168
• 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: Closed access
• Created on: 2024-06-24 12:13:18