scholarly journals InterCriteria Analysis for selection of specific growth rate models of batch cultivation by Saccharomyces cerevisiae yeast for ethanol production

2019 ◽  
Vol 25 (2) ◽  
pp. 77-87
Author(s):  
Mitko Petrov ◽  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Ethanol Production ◽  
Specific Growth ◽  
Batch Cultivation ◽  
Selection Of

scholarly journals Modelling and Multi-Criteria Decision Making for Selection of Specific Growth Rate Models of Batch Cultivation by Saccharomyces cerevisiae Yeast for Ethanol Production

Fermentation ◽  
2019 ◽  
Vol 5 (3) ◽  
pp. 61 ◽  
Author(s):  
Petrov
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Decision Making ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Batch Cultivation ◽  
Preference Ranking ◽  
Multi Criteria Decision Making ◽  
Promethee Ii ◽  
Selection Of

This study is focused on using multi-criteria decision making (MCDM) for selecting specific growth rate models of batch cultivation by the Saccharomyces cerevisiae. Ten specific growth rate models—Monod, Mink, Tessier, Moser, Aiba, Andrews, Haldane, Luong, Edward, and Han-Levenspiel—were investigated in order to explain the cell growth kinetics by the dependence on glucose. By using the preference ranking organization method (PROMETHEE) II, it was found that the Andrews model was the highest of rank and was the most appropriate one for modelling.

scholarly journals Influence of organic acids and organochlorinated insecticides on metabolism of Saccharomyces cerevisiae

2005 ◽  
pp. 207-215 ◽  
Author(s):  
Dusanka Pejin ◽  
Vesna Vasic
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rate ◽  
Sugar Beet ◽  
Specific Growth Rate ◽  
Glycogen Content ◽  
Specific Growth ◽  
Raw Materials ◽  
Stress Factors ◽  
Adaptive Mechanism ◽  
Ribonucleic Acids

Saccharomyces cerevisiae is exposed to different stress factors during the production: osmotic, temperature, oxidative. The response to these stresses is the adaptive mechanism of cells. The raw materials Saccharomyces cerevisiae is produced from, contain metabolism products of present microorganisms and protective agents used during the growth of sugar beet for example the influence of acetic and butyric acid and organochlorinated insecticides, lindan and heptachlor, on the metabolism of Saccharomyces cerevisiae was investigated and presented in this work. The mentioned compounds affect negatively the specific growth rate, yield, content of proteins, phosphorus, total ribonucleic acids. These compounds influence the increase of trechalose and glycogen content in the Saccharomyces cerevisiae cells.

scholarly journals Effect of Specific Growth Rate on Fermentative Capacity of Baker’s Yeast

1998 ◽  
Vol 64 (11) ◽  
pp. 4226-4233 ◽  
Author(s):  
Pim Van Hoek ◽  
Johannes P. Van Dijken ◽  
Jack T. Pronk
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Ethanol Production ◽  
Growth Rates ◽  
Specific Growth ◽  
Pyruvate Decarboxylase ◽  
Baker's Yeast ◽  
Fermentative Capacity ◽  
Yeast Biomass ◽  
Specific Growth Rates

ABSTRACT The specific growth rate is a key control parameter in the industrial production of baker’s yeast. Nevertheless, quantitative data describing its effect on fermentative capacity are not available from the literature. In this study, the effect of the specific growth rate on the physiology and fermentative capacity of an industrialSaccharomyces cerevisiae strain in aerobic, glucose-limited chemostat cultures was investigated. At specific growth rates (dilution rates, D) below 0.28 h−1, glucose metabolism was fully respiratory. Above this dilution rate, respirofermentative metabolism set in, with ethanol production rates of up to 14 mmol of ethanol · g of biomass−1 · h−1at D = 0.40 h−1. A substantial fermentative capacity (assayed offline as ethanol production rate under anaerobic conditions) was found in cultures in which no ethanol was detectable (D < 0.28 h−1). This fermentative capacity increased with increasing dilution rates, from 10.0 mmol of ethanol · g of dry yeast biomass−1 · h−1 at D= 0.025 h−1 to 20.5 mmol of ethanol · g of dry yeast biomass−1 · h−1 atD = 0.28 h−1. At even higher dilution rates, the fermentative capacity showed only a small further increase, up to 22.0 mmol of ethanol · g of dry yeast biomass−1 · h−1 at D= 0.40 h−1. The activities of all glycolytic enzymes, pyruvate decarboxylase, and alcohol dehydrogenase were determined in cell extracts. Only the in vitro activities of pyruvate decarboxylase and phosphofructokinase showed a clear positive correlation with fermentative capacity. These enzymes are interesting targets for overexpression in attempts to improve the fermentative capacity of aerobic cultures grown at low specific growth rates.

scholarly journals Anaplerotic reactions active during growth of Saccharomyces cerevisiae on glycerol

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Joeline Xiberras ◽  
Mathias Klein ◽  
Celina Prosch ◽  
Zahabiya Malubhoy ◽  
Elke Nevoigt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Pyruvate Carboxylase ◽  
Reference Strain ◽  
Specific Growth ◽  
Glyoxylate Cycle ◽  
Maximum Specific Growth Rate ◽  
The Glyoxylate Cycle ◽  
Anaplerotic Reactions

ABSTRACT Anaplerotic reactions replenish TCA cycle intermediates during growth. In Saccharomyces cerevisiae, pyruvate carboxylase and the glyoxylate cycle have been experimentally identified to be the main anaplerotic routes during growth on glucose (C6) and ethanol (C2), respectively. The current study investigates the importance of the two isoenzymes of pyruvate carboxylase (PYC1 and PYC2) and one of the key enzymes of the glyoxylate cycle (ICL1) for growth on glycerol (C3) as a sole carbon source. As the wild-type strains of the CEN.PK family are unable to grow in pure synthetic glycerol medium, a reverse engineered derivative showing a maximum specific growth rate of 0.14 h−1 was used as the reference strain. While the deletion of PYC1 reduced the maximum specific growth rate by about 38%, the deletion of PYC2 had no significant impact, neither in the reference strain nor in the pyc1Δ mutant. The deletion of ICL1 only marginally reduced growth of the reference strain but further decreased the growth rate of the pyc1 deletion strain by 20%. Interestingly, the triple deletion (pyc1Δ pyc2Δ icl1Δ) did not show any growth. Therefore, both the pyruvate carboxylase and the glyoxylate cycle are involved in anaplerosis during growth on glycerol.

scholarly journals Modeling and Use of Inter-Criteria Decision Analysis for Selecting Growth Rate Models for Batch Cultivation of Yeast Kluyveromyces marxianus var. lactis MC 5

Fermentation ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 163
Author(s):  
Mitko Petrov
Keyword(s):  
Growth Rate ◽  
Decision Analysis ◽  
Specific Growth ◽  
Batch Cultivation ◽  
Process Models ◽  
Monod Model ◽  
First Time ◽  
Kinetics Of ◽  
Additive Form ◽  
Selection Of

Ten unstructured models of Monod, Mink, Tessier, Moser, Aiba, Andrews, Haldane, Luong, Edward, and Han-Levenspiel are considered in this paper to explain the kinetics of cell growth for batch cultivation of the yeast Kluyweromyces marxianus var. lactis MC 5. For the first time, two independent kinetic models are used to model the process for the two basic substrates—lactose and oxygen. The selection of the most appropriate growth rate models has been made through a new multi-criteria decision-making approach called the Inter-Criteria Decision Analysis (ICDA) method. The application of ICDA to the growth rate of lactose and oxygen alone has shown that there have been many correlations between the studied models. Thus, the models for the growth rate, depending only on lactose, are reduced to one—Monod model and there are two models—Monod and Mink—depending on oxygen only. Separate kinetic process models have been developed for the combination of Monod–Monod and Monod–Mink models. For the first time, in addition to the multiplicative form, the additive form of a specific growth rate has been studied. The comparison of the obtained results has shown that the additive form has shown better results than the multiplicative one. For this reason, the additive form of the Monod–Monod model will be used to model the process.

scholarly journals KINETIC EVALUATION OF ETHANOL-TOLERANT THERMOPHILE Geobacillus thermoglucosidasius M10EXG FOR ETHANOL PRODUCTION

2016 ◽  
Vol 10 (1) ◽  
pp. 24
Author(s):  
Eny Ida Riyanti ◽  
Peter L. Rogers
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Ethanol Production ◽  
Yeast Extract ◽  
Biomass Yield ◽  
Specific Growth ◽  
Kinetic Evaluation ◽  
Geobacillus Thermoglucosidasius ◽  
Low Level ◽  
Wide Range

Thermophiles are challenging to be studied for ethanol production using agricultural waste containing lignocellulosic materials rich in hexose and pentose. These bacteria have many advantages such as utilizing a wide range of substrates, including pentose (C5) and hexose (C6). In ethanol production, it is important to use ethanol tolerant strain capable in converting lignocellulosic hydrolysate. This study was aimed to investigate the growth profile of ethanol-tolerant thermophile Geobacillus thermoglucosidasius M10EXG using a defined growth medium consisted of single carbon glucose (TGTV), xylose (TXTV), and a mixture of glucose and xylose (TGXTV), together with the effect of yeast extract addition<br />to the media. The experiments were conducted at the School of Biotechnology and Biomolecular Sciences of The University of New South Wales, Australia on a shake flask fermentation at 60°C in duplicate experiment. Cultures were sampled every two hours and analised for their kinetic parameters including the maximum specific growth rate (µmax), biomass yield (Yx/s), ethanol and by-product yields (acetate and L-lactate) (Yp/s), and the doubling time (Td). Results showed that this strain was capable of growing on minimal medium containing glucose or xylose as a single carbon source. This strain utilized glucose and xylose simultaneously (co-fermentation), although there was glucose repression of xylose at relatively low glucose concentration (0.5% w/v), particularly when yeast extract (0.2% w/v) was added to the medium. The highest biomass yield was obtained at 0.5 g l-1 on glucose medium; the yield increased when yeast extract was added (at 0.59 g l-1). The highest specific growth rate of 0.25 was obtained in the phase I growth when the strain was grown on a mixture of glucose and xylose (0.5% : 0.5% w/v) medium. Diauxic growth was shown on the mixture of glucose, xylose, and yeast extract. The strain produced low level of ethanol (0.1 g l-1), as well as low level (0.2 g l-1) of by-products (L-lactate and acetate) after 15 hours. The results suggests its potential application for fermenting lignocellulosic agricultural wastes for ethanol production.

scholarly journals Laboratory Evolution of a Biotin-Requiring Saccharomyces cerevisiae Strain for Full Biotin Prototrophy and Identification of Causal Mutations

2017 ◽  
Vol 83 (16) ◽  
Author(s):  
Jasmine M. Bracher ◽  
Erik de Hulster ◽  
Charlotte C. Koster ◽  
Marcel van den Broek ◽  
Jean-Marc G. Daran ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Baker’S Yeast ◽  
Industrial Biotechnology ◽  
Baker's Yeast ◽  
Laboratory Evolution ◽  
Content Type ◽  
Study Laboratory

ABSTRACT Biotin prototrophy is a rare, incompletely understood, and industrially relevant characteristic of Saccharomyces cerevisiae strains. The genome of the haploid laboratory strain CEN.PK113-7D contains a full complement of biotin biosynthesis genes, but its growth in biotin-free synthetic medium is extremely slow (specific growth rate [μ] ≈ 0.01 h−1). Four independent evolution experiments in repeated batch cultures and accelerostats yielded strains whose growth rates (μ ≤ 0.36 h−1) in biotin-free and biotin-supplemented media were similar. Whole-genome resequencing of these evolved strains revealed up to 40-fold amplification of BIO1, which encodes pimeloyl-coenzyme A (CoA) synthetase. The additional copies of BIO1 were found on different chromosomes, and its amplification coincided with substantial chromosomal rearrangements. A key role of this gene amplification was confirmed by overexpression of BIO1 in strain CEN.PK113-7D, which enabled growth in biotin-free medium (μ = 0.15 h−1). Mutations in the membrane transporter genes TPO1 and/or PDR12 were found in several of the evolved strains. Deletion of TPO1 and PDR12 in a BIO1-overexpressing strain increased its specific growth rate to 0.25 h−1. The effects of null mutations in these genes, which have not been previously associated with biotin metabolism, were nonadditive. This study demonstrates that S. cerevisiae strains that carry the basic genetic information for biotin synthesis can be evolved for full biotin prototrophy and identifies new targets for engineering biotin prototrophy into laboratory and industrial strains of this yeast. IMPORTANCE Although biotin (vitamin H) plays essential roles in all organisms, not all organisms can synthesize this vitamin. Many strains of baker's yeast, an important microorganism in industrial biotechnology, contain at least some of the genes required for biotin synthesis. However, most of these strains cannot synthesize biotin at all or do so at rates that are insufficient to sustain fast growth and product formation. Consequently, this expensive vitamin is routinely added to baker's yeast cultures. In this study, laboratory evolution in biotin-free growth medium yielded new strains that grew as fast in the absence of biotin as in its presence. By analyzing the DNA sequences of evolved biotin-independent strains, mutations were identified that contributed to this ability. This work demonstrates full biotin independence of an industrially relevant yeast and identifies mutations whose introduction into other yeast strains may reduce or eliminate their biotin requirements.

scholarly journals Relationship between pH and Medium Dissolved Solids in Terms of Growth and Metabolism of Lactobacilli and Saccharomyces cerevisiae during Ethanol Production

2005 ◽  
Vol 71 (5) ◽  
pp. 2239-2243 ◽  
Author(s):  
Neelakantam V. Narendranath ◽  
Ronan Power
Keyword(s):  
Growth Rate ◽  
Lactic Acid ◽  
Specific Growth Rate ◽  
Ethanol Production ◽  
Growth Rates ◽  
Specific Growth ◽  
Lactic Acid Production ◽  
Good Practice ◽  
Medium Ph ◽  
Dissolved Solids

ABSTRACT The specific growth rates of four species of lactobacilli decreased linearly with increases in the concentration of dissolved solids (sugars) in liquid growth medium. This was most likely due to the osmotic stress exerted by the sugars on the bacteria. The reduction in growth rates corresponded to decreased lactic acid production. Medium pH was another factor studied. As the medium pH decreased from 5.5 to 4.0, there was a reduction in the specific growth rate of lactobacilli and a corresponding decrease in the lactic acid produced. In contrast, medium pH did not have any significant effect on the specific growth rate of yeast at any particular concentration of dissolved solids in the medium. However, medium pH had a significant (P < 0.001) effect on ethanol production. A medium pH of 5.5 resulted in maximal ethanol production in all media with different concentrations of dissolved solids. When the data were analyzed as a 4 (pH levels) by 4 (concentrations of dissolved solids) factorial experiment, there was no synergistic effect (P > 0.2923) observed between pH of the medium and concentration of dissolved solids of the medium in reducing bacterial growth and metabolism. The data suggest that reduction of initial medium pH to 4.0 for the control of lactobacilli during ethanol production is not a good practice as there is a reduction (P < 0.001) in the ethanol produced by the yeast at pH 4.0. Setting the mash (medium) with ≥30% (wt/vol) dissolved solids at a pH of 5.0 to 5.5 will minimize the effects of bacterial contamination and maximize ethanol production by yeast.

Sign in / Sign up

Export Citation Format

Share Document