Flocculation characteristics of an isolated mutant flocculent Saccharomyces cerevisiae strain and its application for fuel ethanol production from kitchen refuse

Ma, Kedong; Wakisaka, Minato; Sakai, Kokki; Shirai, Yoshihito

doi:10.1016/j.biortech.2008.11.010

Cited by 37 publications

(19 citation statements)

References 11 publications

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“…6). The cells took up all the sugars more quickly as the fermentation was repeated, confirming a previous report (Ma et al, 2009). The time to complete fermentation was reduced from 48 h in the first batch to 24 h in the third batch.…”

Section: Discussionsupporting

confidence: 89%

Efficient Production of Ethanol from Saccharified Crops Mixed with Cheese Whey by the Flex Yeast Kluyveromyces marxianus KD-15

Nakamura

Shinomiya²,

Orikasa

et al. 2012

FSTR

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Ethanol production from a mixture of wheat flour or potato tubers and cheese whey was examined using the flex yeast Kluyveromyces marxianus KD-15, a 2-deoxyglucose-resistant mutant of strain NBRC 1963 that can produce ethanol from sugar beet thick juice diluted with whey. Strain KD-15 simultaneously converted glucose and lactose to ethanol within 48 h, in media containing 10.0% to 15.0% (w/v) total sugars from saccharified filtrate and whey. For efficient production of ethanol from 15.0% (w/v) total sugars, KD-15 cells were collected after fermentation and inoculated into fresh media. Batch fermentation was successfully repeated at least ten times in medium composed of saccharified potato tubers mixed with whey. Yeast cells began to convert all the sugars to ethanol within 24 h, accompanied by cell propagation after the third batch.

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Section: Discussionsupporting

confidence: 89%

Efficient Production of Ethanol from Saccharified Crops Mixed with Cheese Whey by the Flex Yeast Kluyveromyces marxianus KD-15

Nakamura

Shinomiya²,

Orikasa

et al. 2012

FSTR

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“…These flocculins are responsible for ‘flocculation’ of yeast cells, a trait of major importance in the wine, beer, and biofuel industry. The instability of the tandem repeats in these genes, which are causing expansion and contraction in the gene size, has allowed for the fast isolation of spontaneous mutants with altered flocculation characteristics (Hammond, 1996; Verstrepen et al ., 2005; Ma et al ., 2009). Additionally, the available arsenal of flocculins in Saccharomyces yeasts is hugely increased by the generation of chimeric FLO genes by ectopic recombination, which resulted in a huge diversity in the flocculation phenotype of industrial strains (Christiaens et al ., 2012).…”

Section: Natural and Artificial Diversitymentioning

confidence: 99%

Improving industrial yeast strains: exploiting natural and artificial diversity

Steensels¹,

Snoek²,

Meersman³

et al. 2014

FEMS Microbiol Rev

380

288

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Yeasts have been used for thousands of years to make fermented foods and beverages, such as beer, wine, sake, and bread. However, the choice for a particular yeast strain or species for a specific industrial application is often based on historical, rather than scientific grounds. Moreover, new biotechnological yeast applications, such as the production of second-generation biofuels, confront yeast with environments and challenges that differ from those encountered in traditional food fermentations. Together, this implies that there are interesting opportunities to isolate or generate yeast variants that perform better than the currently used strains. Here, we discuss the different strategies of strain selection and improvement available for both conventional and nonconventional yeasts. Exploiting the existing natural diversity and using techniques such as mutagenesis, protoplast fusion, breeding, genome shuffling and directed evolution to generate artificial diversity, or the use of genetic modification strategies to alter traits in a more targeted way, have led to the selection of superior industrial yeasts. Furthermore, recent technological advances allowed the development of high-throughput techniques, such as ‘global transcription machinery engineering’ (gTME), to induce genetic variation, providing a new source of yeast genetic diversity.

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“…The highly flocculent phenotype of the strain T1-E was exploited for repeated-batch operation, with the flocculated biomass being recycled simply by sedimentation as described in the section Materials and methods. This type of operation with flocculent yeasts has been very recently used by other authors for the production of fuel ethanol [4,28,30]. It provides several advantages of industrial relevance, including: (1) fast and convenient separation of yeast cells from the fermentation broth by sedimentation, thus avoiding costly centrifugation steps in the industrial process; (2) biomass accumulation along the consecutive batches for high-cell-density fermentations, which may represent gains in process productivity; (3) the system positively selects for the accumulation of flocculated cells, since free (nonflocculated) cells are removed with the cleared fermentation broth, which enhances operational stability; (4) prevention of contaminations, due to increased yeast cell densities and avoidance of centrifugation steps.…”

Section: Repeated-batch Whey Fermentations In An Air-lift Bioreactor mentioning

confidence: 99%

Fermentation of deproteinized cheese whey powder solutions to ethanol by engineered Saccharomyces cerevisiae: effect of supplementation with corn steep liquor and repeated-batch operation with biomass recycling by flocculation

Silva¹,

Guimarães²,

Teixeira³

et al. 2010

J Ind Microbiol Biotechnol

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The lactose in cheese whey is an interesting substrate for the production of bulk commodities such as bio-ethanol, due to the large amounts of whey surplus generated globally. In this work, we studied the performance of a recombinant Saccharomyces cerevisiae strain expressing the lactose permease and intracellular beta-galactosidase from Kluyveromyces lactis in fermentations of deproteinized concentrated cheese whey powder solutions. Supplementation with 10 g/l of corn steep liquor significantly enhanced whey fermentation, resulting in the production of 7.4% (v/v) ethanol from 150 g/l initial lactose in shake-flask fermentations, with a corresponding productivity of 1.2 g/l/h. The flocculation capacity of the yeast strain enabled stable operation of a repeated-batch process in a 5.5-l air-lift bioreactor, with simple biomass recycling by sedimentation of the yeast flocs. During five consecutive batches, the average ethanol productivity was 0.65 g/l/h and ethanol accumulated up to 8% (v/v) with lactose-to-ethanol conversion yields over 80% of theoretical. Yeast viability (>97%) and plasmid retention (>84%) remained high throughout the operation, demonstrating the stability and robustness of the strain. In addition, the easy and inexpensive recycle of the yeast biomass for repeated utilization makes this process economically attractive for industrial implementation.

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Flocculation characteristics of an isolated mutant flocculent Saccharomyces cerevisiae strain and its application for fuel ethanol production from kitchen refuse

Cited by 37 publications

References 11 publications

Efficient Production of Ethanol from Saccharified Crops Mixed with Cheese Whey by the Flex Yeast Kluyveromyces marxianus KD-15

Efficient Production of Ethanol from Saccharified Crops Mixed with Cheese Whey by the Flex Yeast Kluyveromyces marxianus KD-15

Improving industrial yeast strains: exploiting natural and artificial diversity

Fermentation of deproteinized cheese whey powder solutions to ethanol by engineered Saccharomyces cerevisiae: effect of supplementation with corn steep liquor and repeated-batch operation with biomass recycling by flocculation

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