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Doctoral Thesis
Author of thesis: Ing. Vendula Hrabalová
Acad. year: 2025/2026
Supervisor: prof. Ing. Stanislav Obruča, Ph.D.
Reviewers: doc. Ing. Barbora Branská, PhD., doc. Mgr. Pavel Dvořák, Ph.D.
The doctoral thesis focuses on the use of lignocellulosic waste materials for the production of value-added substances. In the first part, the composition of lignocellulose, its pretreatment and processing options, and microbial inhibitors that slow down fermentation processes are described in detail. Among these inhibitors is ferulic acid, which some microorganisms can biotransform into sensory active substances such as vanillin, vanillyl alcohol, vanillic acid, and others. Furthermore, the thesis focuses on polyhydroxyalkanoates (PHAs): their biosynthesis, biodegradation, utilization, and the possibility of cheapening the production process of these biopolymers. The experimental part focuses on optimizing the hydrolysis process of lignocellulosic materials, specifically wheat bran and brew spent grains. Neutral hydrolysis followed by enzymatic hydrolysis was selected to achieve high saccharide concentration and to minimize the content of phenolic compounds (microbial inhibitors). Selected bacterial strains were subsequently cultivated on the hydrolysates. The highest PHA production was observed in halophilic bacterial strains (Halomonas halophila and Halomonas organivorans). The work's second part focuses on the biotransformation of ferulic acid to sensory active substances (mainly vanillic acid and vanillyl alcohol) using different bacterial strains. The highest biotransformation potential was observed with the thermophilic bacterium Caldimonas thermodepolymerans and the halophilic bacterium Halomonas neptunia, and further detailed experiments were performed with these strains.
Lignocellulose, wheat bran, brew spent grain, polyhydroxyalkanoates, hydrolysis, biotransformation, ferulic acid, vanillic acid, vanillyl alcohol, 4-vinylguaiacol.
Date of defence
22.01.2026
Result of the defence
Defended (thesis was successfully defended)
Process of defence
Předsedkyně komise představila doktorandku a předala jí slovo. Ing. Hrabalová v roce 2023 absolvovala pedagogické minimum. Již nyní má poměrně velké množství pracovních zkušeností. Doktorandka má tři recenzované publikace v časopisech, z toho ve dvou případech je první autorkou. Je také spoluautorkou velkého množství konferenčních příspěvků.
Language of thesis
Czech
Faculty
Fakulta chemická
Department
Institute of Food Science and Biotechnology
Study programme
Biophysical Chemistry (DKCP_BCH)
Composition of Committee
prof. RNDr. Ivana Márová, CSc. (předseda) doc. Mgr. Pavel Dvořák, Ph.D. (člen) doc. Ing. Barbora Branská, PhD. (člen) prof. RNDr. Zbyněk Zdráhal, Dr. (člen) prof. Mgr. Marek Koutný, Ph.D. (člen) doc. Ing. Petr Sedláček, Ph.D. (člen) doc. Ing. Pavel Diviš, Ph.D. (člen)
Supervisor’s reportprof. Ing. Stanislav Obruča, Ph.D.
Reviewer’s reportdoc. Ing. Barbora Branská, PhD.
Reviewer’s reportdoc. Mgr. Pavel Dvořák, Ph.D.
Responsibility: Mgr. et Mgr. Hana Odstrčilová