Yeast Physical (Shear) Stress: The Engineering Perspective

Stafford, Robert A.

doi:10.1002/9780470696040.ch4

Cited by 6 publications

(4 citation statements)

References 9 publications

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“…It is known that K L a can be enhanced with higher mixing rates [5,12] as demonstrated by the impeller experiment. However, increased mixing increases shear stress on cells and can potentially damage them [36]. The highest K L a for a bioreactor, which was nearly 10 times higher than the average values in Table 3, was achieved with a PDMS filter at a high flow rate.…”

Section: Discussionmentioning

confidence: 81%

Methods for Oxygenation of Continuous Cultures of Brewer’s Yeast, Saccharomyces cerevisiae

et al. 2021

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Maintaining steady-state, aerobic cultures of yeast in a bioreactor depends on the configuration of the bioreactor system as well as the growth medium used. In this paper, we compare several conventional aeration methods with newer filter methods using a novel optical sensor array to monitor dissolved oxygen, pH, and biomass. With conventional methods, only a continuously stirred tank reactor configuration gave high aeration rates for cultures in yeast extract peptone dextrose (YPD) medium. For filters technologies, only a polydimethylsiloxan filter provided sufficient aeration of yeast cultures. Further, using the polydimethylsiloxan filter, the YPD medium gave inferior oxygenation rates of yeast compared to superior results with Synthetic Complete medium. It was found that the YPD medium itself, not the yeast cells, interfered with the filter giving the low oxygen transfer rates based on the volumetric transfer coefficient (KLa). The results are discussed for implications of miniaturized bioreactors in low-gravity environments.

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Section: Discussionmentioning

confidence: 81%

Methods for Oxygenation of Continuous Cultures of Brewer’s Yeast, Saccharomyces cerevisiae

et al. 2021

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“…In addition, there are studies that indicate that shear stress can negatively impact cells. For example, while shear stress may not induce cell death, such stress on microalgae or yeast may cause a decreased growth rate ( 42 , 43 ). Shear stress can even reduce the expression of a recombinant protein in CHO cells ( 44 ).…”

Section: Discussionmentioning

confidence: 99%

High-throughput selection of cells based on accumulated growth and division using PicoShell particles

Zee

Rutte

Rumyan

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Production of high-energy lipids by microalgae may provide a sustainable energy source that can help tackle climate change. However, microalgae engineered to produce more lipids usually grow slowly, leading to reduced overall yields. Unfortunately, culture vessels used to select cells based on growth while maintaining high biomass production, such as well plates, water-in-oil droplet emulsions, and nanowell arrays, do not provide production-relevant environments that cells experience in scaled-up cultures (e.g., bioreactors or outdoor cultivation farms). As a result, strains that are developed in the laboratory may not exhibit the same beneficial phenotypic behavior when transferred to industrial production. Here, we introduce PicoShells, picoliter-scale porous hydrogel compartments, that enable >100,000 individual cells to be compartmentalized, cultured in production-relevant environments, and selected based on growth and bioproduct accumulation traits using standard flow cytometers. PicoShells consist of a hollow inner cavity where cells are encapsulated and a porous outer shell that allows for continuous solution exchange with the external environment. PicoShells allow for cell growth directly in culture environments, such as shaking flasks and bioreactors. We experimentally demonstrate that Chlorella sp., Saccharomyces cerevisiae, and Chinese hamster ovary cells, used for bioproduction, grow to significantly larger colony sizes in PicoShells than in water-in-oil droplet emulsions (P < 0.05). We also demonstrate that PicoShells containing faster dividing and growing Chlorella clonal colonies can be selected using a fluorescence-activated cell sorter and regrown. Using the PicoShell process, we select a Chlorella population that accumulates chlorophyll 8% faster than does an unselected population after a single selection cycle.

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“…The use of disk‐stack centrifuges at high G ‐force for cropping brewer's yeast cells has been shown to have a negative effect on its viability (Stafford ; Chlup and others ). When grown aerobically, as is the case for baker's yeast, brewing yeast cells were less sensitive to cell rupture than anaerobic cells and this might be attributed to the high resistance of yeast cell walls (van Bergen ).…”

Section: Separation (Harvesting)mentioning

confidence: 99%

Compressed Baker's Yeast: Mapping Patents on Post‐Fermentation Processes

Gélinas

2017

Comp Rev Food Sci Food Safe

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In the baking industry, fresh yeast is generally available as a compressed paste containing about 70% moisture. While much literature has been published on its growth conditions in fermentation tanks, little information may be obtained on the final steps of baker's yeast production. In this review, 226 patents were found on the separation of yeast cells from spent growth media as well as its dewatering, forming, and packaging in the compressed form. The latter corresponded to 21% of 1096 unique families of patented inventions filed worldwide between 1787 and 2014 on the production of fresh baker's yeast. Patent specifications disclosed key technical information not available in scientific journals. Particularly between 1890 and 1960, highly specific equipment such as centrifugal separators, rotary vacuum filters, and extruding and cutting units were proposed. Compressed yeast may contain small amounts of processing aids, including water-absorbing agents such as starch and salt, as well as plasticizing and whitening agents. Any variation in yeast solids and moisture contents will affect its gassing power and keeping properties. Disposal and proper treatment of very large volumes of spent growth media will remain a major challenge to the baker's yeast industry.

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Yeast Physical (Shear) Stress: The Engineering Perspective

Cited by 6 publications

References 9 publications

Methods for Oxygenation of Continuous Cultures of Brewer’s Yeast, Saccharomyces cerevisiae

Methods for Oxygenation of Continuous Cultures of Brewer’s Yeast, Saccharomyces cerevisiae

High-throughput selection of cells based on accumulated growth and division using PicoShell particles

Compressed Baker's Yeast: Mapping Patents on Post‐Fermentation Processes

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