Bioethanol strains of Saccharomyces cerevisiae characterised by microsatellite and stress resistance

Abstract

Strains of Saccharomyces cerevisiae may display characteristics that are typical of rough-type colonies, made up of cells clustered in pseudohyphal structures and comprised of daughter buds that do not separate from the mother cell post-mitosis. These strains are known to occur frequently in fermentation tanks with significant lower ethanol yield when compared to fermentations carried out by smooth strains of S. cerevisiae that are composed of dispersed cells. In an attempt to delineate genetic and phenotypic differences underlying the two phenotypes, this study analysed 10 microsatellite loci of 22 S. cerevisiae strains as well as stress resistance towards high concentrations of ethanol and glucose, low pH and cell sedimentation rates. The results obtained from the phenotypic tests by Principal-Component Analysis revealed that unlike the smooth colonies, the rough colonies of S. cerevisiae exhibit an enhanced resistance to stressful conditions resulting from the presence of excessive glucose and ethanol and high sedimentation rate. The microsatellite analysis was not successful to distinguish between the colony phenotypes as phenotypic assays. The relevant industrial strain PE-2 was observed in close genetic proximity to rough-colony although it does not display this colony morphology. A unique genetic pattern specific to a particular phenotype remains elusive.

KINERJA MIKROBA Zymomonas mobilis DAN Saccharomyces cerevisiae UNTUK MENGURAIKAN HIDROLISAT TONGKOL JAGUNG MENJADI BIOETANOL DENGAN PENGARUH WAKTU FERMENTASI DAN RASIO PENAMBAHAN MIKROBA

“…Tahapan tersebut menghasilkan bioetanol terbaik dengan menggunakan campuran kedua mikroba pada waktu fermentasi 4 hari. [23].…”

“…Pertumbuhan Saccharomyces cerevisiae dan Zymomonas mobilis tentu tidak sama, karena kedua mikroba tersebut merupakan mikroba dengan kingdom yang berbeda. Saccharomyces cerevisiae berasal dari kingdom fungi yang secara morfologi tumbuh berbentuk blastospora berbentuk bulat lonjong, silindris, oval atau bulat telur yang dipengaruhi oleh strainnya (Gambar 1a) [23]. Sedangkan Zymomonas mobilis berasal dari kingdom bakteri yang tumbuh menyebar dan tidak beraturan hingga memenuhi cawan (Gambar 1b)…”

Morphophysiological and molecular characterization of wild yeast isolates from industrial ethanol process

“…This mechanism is activated by cell-surface adhesions; the flocculin (Flo) proteins are activated in response to stressing conditions (El-Kirat-Chatel et al, 2015). This response is mainly regulated by environmental conditions such as changes in pH and ethanol concentration or nitrogen and glucose depletion (Braus et al, 2003;Rossouw et al, 2015;Reis et al, 2016;Stewart, 2009). On the other hand, some S. cerevisiae strains can show sexual aggregation patterns, described as co-flocculation and cell chain formation, derived from the failure of the bud to separate itself from its mother cell, resulting in an aggregation of approximately 30 to 50 cells, unable to regroup after being mechanically dispersed (Soares, 2010).…”

Potential of Thermotolerant Ethanologenic Yeasts Isolated from ASEAN Countries and Their Application in High- Temperature Fermentation

“…Since microorganisms are essential for material production through bio-processing, their characteristics and traits are crucial for the production process efficiency. Ethanologenic yeast, Saccharomyces cerevisiae, has been traditionally and widely utilized for the production of alcoholic beverages and bioethanol [4,5]. Industrially common problems in bio-ethanol production related to S. cerevisiae strains are temperature level (35-45°C) and high ethanol concentration (over 20%) [6].…”