Wydział Biotechnologii i Nauk o Żywności / Faculty of Biotechnology and Food Sciences / W5
Stały URI zbioruhttp://hdl.handle.net/11652/5
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Pozycja Acid whey as a medium for cultivation of conventional and non-conventional yeasts(Lodz University of Technology Press, 2016) Dudkiewicz, Marta; Berlowska, Joanna; Kregiel, DorotaThe aim of this study was to investigate the capacity of different yeast strains to grow on acid whey and assimilate different carbon sources. Twenty different yeasts (with GRAS status) were tested, sourced from the LOCK105 Culture Collection (Poland) and the National Collection of Yeast Cultures (Great Britain). The acid whey, from cows was characterized in terms of it main chemical components (carbohydrates, organic acids, aminoacids, FAN, total nitrogen) using HPLC techniques and chemical methods. The best producer of biomass (of conventional yeast strains) was S. cerevisiae Ja64 (biomass yield 1.16 g of dry mass/l), while among non-conventional yeasts the highest increase of biomass showed the strain D. hansenii, reaching the biomass yield of 1.12 g of dry mass/l.Pozycja Effect of nitrogen sources on fermentation process and formation of hydrogen sulfide and ethyl carbamate by wine yeast(Wydawnictwo Politechniki Łódzkiej, 2013) Nowak, Agnieszka; Koch-Wilk, Magdalena; Pogorzelski, Eugeniusz; Czyżowska, AgataThe addition of nitrogen compounds during winemaking is required for the fermentation process to be conducted properly. These compounds are known to be essential to the vinification process, not only because they influence yeast growth but also because they affect the formation of main and by-products. The effect of nitrogen source on in vitro and in situ formation of hydrogen sulfide and ethyl carbamate was studied. Research material comprised two strains of wine yeast: Saccharomyces cerevisiae. In vitro model was carried out in a synthetic defined medium. In situ fermentations were carried out in musts prepared from apple concentration. The process of hydrogen sulfide formation was intensified in nitrogen deficiency. The presence of amino acids in a model substrate resulted in significant changes in the efficiency of formation of both compounds. Yeasts produced more H2S in the presence of Cys, Phe, Gly, Glu, Ile, Thr, Pro, Leu, Trp, Val and less in the presence Ala, Arg, Asp, His, Ser, Met. The formation of ethyl carbamate was limited by the amino acids, except Arg, Asp and Lys, which during fermentation with Syrena yeasts caused an increase in the efficiency of formation of this compound. The Fermivit V preparation stimulated yeasts to form H2S. In the presence of this preparation the Syrena yeasts formed more ethyl carbamate while Hefix yeasts formed about 3-fold less of this compound then in the presence diamonium phosphate.Pozycja Evaluation of yeast cell vitality using different fluorescent dyes(Wydawnictwo Politechniki Łódzkiej, 2009) Kręgiel, Dorota; Berłowska, JoannaVitality of different industrial yeast strains was investigated using four standard fluorescent dyes by studying changes in microscopic evaluation of yeast nuclei and cell membranes. Fluorescent dyes were: acridine orange, DAPI, trypan blue and primuline. Comparison of the results obtained by fluorescent techniques with these dyes showed good correlation of yeast cell vitality measurements. Simultaneous staining with fluorochromes provides a powerful way to demonstrate culture heterogenity and changes within yeast cells during long cultivation.