Dorota Kregiel - Academia.edu (original) (raw)

Papers by Dorota Kregiel

Molecules, Feb 22, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Journal of Food Protection, Jun 1, 2015

The aim of the study was to evaluate the adhesion abilities of the acetic acid bacterium Asaia bo... more The aim of the study was to evaluate the adhesion abilities of the acetic acid bacterium Asaia bogorensis to glass and polystyrene in the presence of American cranberry (Vaccinium macrocarpon) juice. The strain of A. bogorensis used was isolated from spoiled commercial fruit-flavored drinking water. The cranberry juice was analyzed for polyphenols, organic acids, and carbohydrates using high-performance liquid chromatography and liquid chromatography-mass spectrometry techniques. The adhesive abilities of bacterial cells in culture medium supplemented with cranberry juice were determined using luminometry and microscopy. The viability of adhered and planktonic bacterial cells was determined by the plate count method, and the relative adhesion coefficient was calculated. This strain of A. bogorensis was characterized by strong adhesion properties that were dependent upon the type of surface. The highest level of cell adhesion was found on the polystyrene. However, in the presence of 10% cranberry juice, attachment of bacterial cells was three times lower. Chemical analysis of juice revealed the presence of sugars, organic acids, and anthocyanins, which were identified as galactosides, glucosides, and arabinosides of cyanidin and peonidin. A-type proanthocyanidins responsible for the antiadhesion properties of V. macrocarpon also were detected.

Bioresources, Apr 18, 2022

Yeast strains and appropriate hydrolysis conditions were selected for efficient single cell prote... more Yeast strains and appropriate hydrolysis conditions were selected for efficient single cell protein (SCP) production from waste rapeseed meal. High potential for effective biomass production was observed for Yarrowia lipolytica LOCK0264 with 10 g of rapeseed meal at 4.9 × 10 8 ± 1.5 × 10 8 (2.91 logarithmic units). The highest yeast multiplication rate was obtained for Metschnikowia pulcherrima NCYC747 with 12.5 g of rapeseed meal and with 15 g of rapeseed meal at 1.6 × 10 8 ± 3.8 × 10 7 and 4.5 × 10 8 ± 4.0 × 10 7 (2.75 and 2.86 logarithmic units, respectively).

Zeszyty Naukowe. Chemia Spożywcza i Biotechnologia / Politechnika Łódzka, 2009

InTech eBooks, Dec 13, 2017

Traditionally the term 'yeast' means Saccharomyces cerevisiae and its close relatives. This yeast... more Traditionally the term 'yeast' means Saccharomyces cerevisiae and its close relatives. This yeast is used in traditional fermentation processes, mainly for ethanol formation, baking, winemaking and beer production. The classical carbon substrates for typical yeast processes are glucose or sucrose, however, the successful expansion of industrial biotechnology drives research toward the utilization of alternative carbon sources. New technologies require very specific challenges and differ from those found in conventional fermentation processes. Most microbial habitats, especially in modern biotechnological processes, do not provide culture media rich in mono-and disaccharides. They include fermentation environments with various compositions of carbon and energy sources as well as the presence of various cytotoxic compounds which inhibit the growth of industrial yeasts. About 1500 various yeast species have been identified nowadays. Microbiologists and biotechnologists have named all non-S. cerevisiae yeasts as 'non-conventional' yeasts. Their features present a potential that can be used for non-conventional processes. Non-Saccharomyces strains provide alternative metabolic routes for substrate utilization and product formation. The diversity of these yeasts includes many species possessing useful, and sometimes uncommon, metabolic features potentially interesting for biotechnology. The selected strains of non-conventional yeasts could be used as pure or mixed cultures for improving industrial fermentations.

BioMed Research International, 2016

Sugar beet pulp, a byproduct of sugar beet processing, can be used as a feedstock in second-gener... more Sugar beet pulp, a byproduct of sugar beet processing, can be used as a feedstock in second-generation ethanol production. The objective of this study was to investigate the effects of pretreatment, of the dosage of cellulase and hemicellulase enzyme preparations used, and of aeration on the release of fermentable sugars and ethanol yield during simultaneous saccharification and fermentation (SSF) of sugar beet pulp-based worts. Pressure-thermal pretreatment was applied to sugar beet pulp suspended in 2% w/w sulphuric acid solution at a ratio providing 12% dry matter. Enzymatic hydrolysis was conducted using Viscozyme and Ultraflo Max (Novozymes) enzyme preparations (0.015-0.02 mL/g dry matter). Two yeast strains were used for fermentation: Ethanol Red (S. cerevisiae) (1 g/L) and Pichia stipitis (0.5 g/L), applied sequentially. The results show that efficient simultaneous saccharification and fermentation of sugar beet pulp was achieved. A 6 h interval for enzymatic activation between the application of enzyme preparations and inoculation with Ethanol Red further improved the fermentation performance, with the highest ethanol concentration reaching 26.9 ± 1.2 g/L and 86.5 ± 2.1% fermentation efficiency relative to the theoretical yield.

Processes, May 19, 2023

Laboratorium - Przegląd Ogólnopolski, 2016

Rapeseed meal (RM) is an important agroindustrial by-product produced in large quantities by oil ... more Rapeseed meal (RM) is an important agroindustrial by-product produced in large quantities by oil extraction from seeds. However, the efficient utilization of RM as animal feed is limited by its low metabolizable energy, poor palatability, and high levels of fiber and anti-nutritional components. Here, we investigate the potential of enriching RM with single-cell protein by fermentation with conventional and unconventional yeasts, to make a nutritionally improved feed component. The process of simultaneous saccharification and fermentation improved the parameters of the waste biomass, especially the protein content, the amount of crude fiber, and the degree of biotransformation of isoflavone compounds present in the waste material. Fermentation yielded the highest protein gain for the Saccharomyces cerevisiae Ethanol Red strain (ΔN=2.38%) at a biomass load of 12.5 g and for Scheffersomyces stipitis (ΔN=2.34%) at an enzyme dose of 0.125ml/10g DM. Crude fiber content (CF) was reduced by 2.55–7.18%. The SSF process resulted in the conversion of isoflavones to forms with fewer adverse effects and lower estrogenic activity.

Fermentation, Jul 5, 2021

Journal of The Institute of Brewing, Jun 20, 2017

Spent yeasts, a co-product from fermentation processes, are a source for unconvential autolysis p... more Spent yeasts, a co-product from fermentation processes, are a source for unconvential autolysis processes. In this study, five post-fermentation yeast strains that are often used in fermentation processes were used: Saccharomyces cerevisiae Ethanol Red (Lessafre), Kluyveromyces marxianus LOCK 0026, K. marxianus NCYC 179, Scheffersomyces stipitis NCYC 1541 and Pichia angusta NCYC 495. Autolysis was conducted at 50°C for 48 hours in the presence of saponins from Quillaja saponaria. The concentrations of proteins and free amino acids in the yeast autolysates were evaluated using IR spectroscopy and chromatography. The lysates were found to be good sources of essential amino acids, which constituted between 29.3% (S. cerevisiae) and 40.7% (K. marxianus LOCK 0026) of the amino acid pools. The largest pools of free amino acids were found in autolysates of S. cerevisiae Ethanol Red (44.9 g/L) and P. angusta NCYC 495 (40.53 g/L). Saponin can be used as an auxiliary or alternative to conventional methods of cell lysis, especially since Q. saponaria extracts are approved for use in foods and could have significant health benefits. The usability of five post-fermentation yeast strains as a source of valuable nitrogen compounds in unconventional salt-free lysates was demonstrated for the first time in the present study.

Fermentation, May 25, 2022

Processes, Jan 29, 2019

Anaerobic fermentation of organic compounds is used in many biotechnological processes and has be... more Anaerobic fermentation of organic compounds is used in many biotechnological processes and has been the subject of much research. A variety of process conditions and different growth media can be used to obtain microbial metabolites. The media must be free from contamination before fermentation. Sterilization is most often achieved by applying heat or other treatments, such as ozonation. Sterilization of liquid media using ozone can be very beneficial, but this method introduces high concentrations of residual oxygen, which inhibit anaerobic processes. Deoxidation is therefore necessary to remove the oxygen from ozonated broths. This study evaluates the effectiveness of three deoxidation agents for two kinds of fermentation media based on malt or molasses: ultrasound, iron(II) sulfate, and Metschnikowia sp. yeast. The time needed for deoxidation varied, depending on the kind of broth and the deoxidation agent. In general, the dynamics of oxygen removal were faster in malt broth. A comparative analysis showed that yeast biomass was the most effective agent, achieving deoxidation in the shortest time. Moreover, the fully deoxidated broth was supplemented with yeast biomass, which is rich in biogenic substrates, expressed as a protein content of 0.13-0.73 g/L. Application of Metschnikowia sp. may therefore be considered as an effective strategy for simultaneous deoxidation and nutrient supplementation of broths used in anaerobic biotechnological processes.

Processes, Jun 24, 2020

Heterotrophic bacteria are able to form biofilms in water processing systems, adhering to pipe ma... more Heterotrophic bacteria are able to form biofilms in water processing systems, adhering to pipe materials and colonizing surfaces. The aim of our research was to identify the critical points in the process of bottled water production at which controls can be applied to prevent, reduce, or eliminate water safety hazards. Microbiological monitoring was conducted using the plate count method and luminometry. To identify the bacterial isolates, we used polyphasic identification based on biochemical tests and molecular analysis using ribosomal RNA. The heterotrophic plate counts were higher in the water filtration station, ultrafiltration (UV) disinfection station, and holding tank. At these points of the industrial process, the water is stagnant or there is poor flow. Molecular analysis identified the bacterial isolates as belonging to Acinetobacter, Agrobacterium, Aeromonas, Brevundimonas, Citrobacter, Enterobacter, Klebsiella, Pantoea, and Rhizobium genera. Bacterial isolates showed various levels of biofilm formation, and the best adhesion properties were exhibited by the Aeromonas hydrophila and Citrobacter freundii strains.

Energies, Aug 23, 2017

Large amounts of waste biomass are generated in sugar factories from the processing of sugar beet... more Large amounts of waste biomass are generated in sugar factories from the processing of sugar beets. After diffusion with hot water to draw the sugar from the beet pieces, a wet material remains called pulp. In this study, waste sugar beet pulp biomass was enzymatically depolymerized, and the obtained hydrolyzates were subjected to fermentation processes. Bioethanol, biomethane, and biohydrogen were produced directly from the substrate or in combined mode. Stillage, a distillery by-product, was used as a feedstock for anaerobic digestion. During biosynthesis of ethanol, most of the carbohydrates released from the sugar beet pulp were utilized by a co-culture of Saccharomyces cerevisiae Ethanol Red, and Scheffersomyces stipitis LOCK0047 giving 12.6 g/L of ethanol. Stillage containing unfermented sugars (mainly arabinose, galactose and raffinose) was found to be a good substrate for methane production (444 dm 3 CH 4 /kg volatile solids (VS)). Better results were achieved with this medium than with enzymatic saccharified biomass. Thermal pre-treatment and adjusting the pH of the inoculum resulted in higher hydrogen production. The largest (p < 0.05) hydrogen yield (252 dm 3 H 2 /kg VS) was achieved with sugar beet stillage (SBS). In contrast, without pre-treatment the same medium yielded 35 dm 3 H 2 /kg VS. However, dark fermentation of biohydrogen was more efficient when sugar beet pulp hydrolyzate was used.

Postępy Mikrobiologii. Suplement, 2017

Przemysł Spożywczy, Feb 5, 2015

Wstęp. Cynk i miedź są mikroelementami niezbędnymi do prawidłowego funkcjonowania organizmu. Częs... more Wstęp. Cynk i miedź są mikroelementami niezbędnymi do prawidłowego funkcjonowania organizmu. Często spotykana niska podaż cynku z pożywieniem jest wskazaniem do jego suplementacji. Wieloskładnikowe preparaty suplementacyjne są chętnie stosowanym źródłem składników mineralnych, w tym Cu i Zn dla organizmu. Materiał i metody. Analizie poddano 22 witaminowo-mineralne suplementy diety dostępne na polskim rynku farmaceutycznym. W preparatach oznaczono stężenie Zn i Cu za pomocą płomieniowej metody AAS. Wyniki. Stężenie Zn i Cu oznaczone w badanych suplementach nie zawsze odpowiadało zawartości deklarowanej przez producentów. Podaż Zn i Cu zaspokajała około 30-150% dziennego zalecanego spożycia dla tych pierwiastków. Wnioski. Dla świadomego używania preparatów suplementacyjnych potrzebne są odpowiednie regulacja prawne dotyczące ich jakości.