Comparison of the Baker's yeast process performance in laboratory and production scale

Georgé, S.; Larsson, Gen; Olsson, K.; Enfors, Sven Olof

doi:10.1007/s004490050423

Cited by 9 publications

(14 citation statements)

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“…In addition, leavening ability in high sugar dough was measured in control and test final products, but there was no considerable difference between them. This finding was not in agreement with the previous work (George et al. 1998).…”

Section: Resultscontrasting

confidence: 99%

“…As the loop time was short (about 8 s) and the specific growth rate was low during the last 7 h and oxygen bubbles were likely to be transferred to the loop via the pump, no oxygen limitation was observed. Therefore, the ethanol was not produced anaerobically in the two states of control and test fermentation (George et al. 1998).…”

Section: Resultsmentioning

confidence: 99%

“…Although having high biomass yield is very important economically, loosing 3·6% yield may be tolerable when this new feeding method results in reasonably higher leavening ability. A high sugar zone in the circulation loop throughout the fermentation process reduces the biomass yield significantly (George et al. 1998).…”

Section: Discussionmentioning

confidence: 99%

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A novel feeding method in commercial Baker’s yeast production

Zamani¹,

Pournia²,

Seirafi³

2008

Journal of Applied Microbiology

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Aims: The aim of this investigation was to determine a better leavening ability and shelf life for the same biomass yield of final product. Methods and Results: A commercial fed‐batch bioreactor equipped with circulation loop was used to study the effect of carbon source, molasses, profile on dough‐leavening ability, shelf life and biomass yield of Baker’s yeast, Saccharomyces cerevisiae. A set of 32 commercial batches were performed to investigate the effect of sugar concentration and compare with 32 control experiments. Conclusions: Higher local sugar concentration in circulation loop resulted in a better leavening ability and shelf life for the same biomass yield of the final product. In addition, this method improved nitrogen assimilation which resulted in higher protein content. Increase in leavening ability and protein content could be a result of the higher levels of glycolytic enzymes. Significance and Impact of the Study: It was observed that this change resulted in considerable improvement in leavening ability and shelf life at a commercial scale. It must be emphasized that to improve product quality, it is not necessary to pursue classical mutagenesis and selection strategies. A high‐quality product can be achieved only by optimizing the feeding profile and strategy.

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Section: Resultscontrasting

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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A novel feeding method in commercial Baker’s yeast production

Zamani¹,

Pournia²,

Seirafi³

2008

Journal of Applied Microbiology

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“…Microorganisms used in large-scale reactor environments are continuously exposed to various types of gradients [96,98]. This comprises also the development of osmotic gradients as a result of the feeding of high concentrated nutrient solutions and insufficient mixing of the culture broth.…”

Section: Resultsmentioning

confidence: 99%

Stress Responses of the Industrial Workhorse Bacillus licheniformis to Osmotic Challenges

et al. 2013

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The Gram-positive endospore-forming bacterium Bacillus licheniformis can be found widely in nature and it is exploited in industrial processes for the manufacturing of antibiotics, specialty chemicals, and enzymes. Both in its varied natural habitats and in industrial settings, B. licheniformis cells will be exposed to increases in the external osmolarity, conditions that trigger water efflux, impair turgor, cause the cessation of growth, and negatively affect the productivity of cell factories in biotechnological processes. We have taken here both systems-wide and targeted physiological approaches to unravel the core of the osmostress responses of B. licheniformis. Cells were suddenly subjected to an osmotic upshift of considerable magnitude (with 1 M NaCl), and their transcriptional profile was then recorded in a time-resolved fashion on a genome-wide scale. A bioinformatics cluster analysis was used to group the osmotically up-regulated genes into categories that are functionally associated with the synthesis and import of osmostress-relieving compounds (compatible solutes), the SigB-controlled general stress response, and genes whose functional annotation suggests that salt stress triggers secondary oxidative stress responses in B. licheniformis. The data set focusing on the transcriptional profile of B. licheniformis was enriched by proteomics aimed at identifying those proteins that were accumulated by the cells through increased biosynthesis in response to osmotic stress. Furthermore, these global approaches were augmented by a set of experiments that addressed the synthesis of the compatible solutes proline and glycine betaine and assessed the growth-enhancing effects of various osmoprotectants. Combined, our data provide a blueprint of the cellular adjustment processes of B. licheniformis to both sudden and sustained osmotic stress.

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“…Mixing times of large-scale bioreactors for microbial cultures exceed 100 s to reach 95% homogeneity, and the circulation time of the cells, which is proportional to the mixing time, is consequently in the magnitude of 10 s and longer depending on the stirring conditions (Delvigne, Destain, & Thonart, 2006;Nagata, 1975). Biomass and product yield reduction are reported for several different strains and processes when a process is scaled up to large scale (Bylund et al, 1998;Enfors et al, 2001;George, Larsson, Olsson, & Enfors, 1998;Xu, Jahic, Blomsten, & Enfors, 1999). Biomass and product yield reduction are reported for several different strains and processes when a process is scaled up to large scale (Bylund et al, 1998;Enfors et al, 2001;George, Larsson, Olsson, & Enfors, 1998;Xu, Jahic, Blomsten, & Enfors, 1999).…”

mentioning

confidence: 99%

CFD predicted pH gradients in lactic acid bacteria cultivations

Spann

Glibstrup

Pellicer-Alborch

et al. 2018

Biotech & Bioengineering

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The formation of pH gradients in a 700 L batch fermentation of Streptococcus thermophilus was studied using multi-position pH measurements and computational fluid dynamics (CFD) modeling. To this end, a dynamic, kinetic model of S. thermophilus and a pH correlation were integrated into a validated one-phase CFD model, and a dynamic CFD simulation was performed. First, the fluid dynamics of the CFD model were validated with NaOH tracer pulse mixing experiments. Mixing experiments and simulations were performed whereas multiple pH sensors, which were placed vertically at different locations in the bioreactor, captured the response.A mixing time of about 46 s to reach 95% homogeneity was measured and predicted at an impeller speed of 242 rpm. The CFD simulation of the S. thermophilus fermentation captured the experimentally observed pH gradients between a pH of 5.9 and 6.3, which occurred during the exponential growth phase. A pH higher than 7 was predicted in the vicinity of the base solution inlet. Biomass growth, lactic acid production, and substrate consumption matched the experimental observations. Moreover, the biokinetic results obtained from the CFD simulation were similar to a single-compartment simulation, for which a homogeneous distribution of the pH was assumed. This indicates no influence of pH gradients on growth in the studied bioreactor. This study verified that the pH gradients during a fermentation in the pilot-scale bioreactor could be accurately predicted using a coupled simulation of a biokinetic and a CFD model. To support the understanding and optimization of industrial-scale processes, future biokinetic CFD studies need to assess multiple types of environmental gradients, like pH, substrate, and dissolved oxygen, especially at industrial scale. K E Y W O R D S computational fluid dynamics (CFD), dynamic simulation, heterogeneities, lactic acid bacteria (LAB) fermentation, pH gradients, transient CFD simulation 1 | INTRODUCTION Heterogeneities of culture parameters like substrate concentrations, pH, and dissolved oxygen concentrations are regarded as mainly responsible for productivity loss in large-scale bioreactor cultivations.Transport limitations occur at large scale due to insufficient mixing, and cells are consequently exposed to fluctuating conditions. Non-limiting substrate concentrations in the range of 0.3-2 g L −1 are reported in feeding zones during fed-batch processes, whereas there are substrate-limited conditions further away from the feeding Biotechnology and Bioengineering. 2019;116:769-780.wileyonlinelibrary.com/journal/bit

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Comparison of the Baker's yeast process performance in laboratory and production scale

Cited by 9 publications

References 0 publications

A novel feeding method in commercial Baker’s yeast production

A novel feeding method in commercial Baker’s yeast production

Stress Responses of the Industrial Workhorse Bacillus licheniformis to Osmotic Challenges

CFD predicted pH gradients in lactic acid bacteria cultivations

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