Effects of high medium pH on growth, metabolism and transport in Saccharomyces cerevisiae

Peña, Antonio; Sánchez, Norma Silvia; Álvarez, Helber; Calahorra, Martha; Ramı́rez, Jorge

doi:10.1093/femsyr/fou005

Cited by 49 publications

(25 citation statements)

References 34 publications

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“…We hypothesized that the low aldehyde titer was due to the low solubility of FFAs limiting their uptake for conversion to aldehyde. Therefore, we raised the pH of the growth medium to pH 5.8 and 7.0 with phosphate buffer to increase FFA solubility; higher pHs were not investigated because alkaline pH inhibits growth (Pena et al, ). Consequently, biotransformation of all chain lengths of FFAs to aldehydes was markedly enhanced with increasing pH.…”

mentioning

confidence: 99%

Whole‐cell biocatalytic and de novo production of alkanes from free fatty acids in Saccharomyces cerevisiae

Foo

Susanto

Keasling

et al. 2016

Biotech & Bioengineering

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Rapid global industrialization in the past decades has led to extensive utilization of fossil fuels, which resulted in pressing environmental problems due to excessive carbon emission. This prompted increasing interest in developing advanced biofuels with higher energy density to substitute fossil fuels and bio‐alkane has gained attention as an ideal drop‐in fuel candidate. Production of alkanes in bacteria has been widely studied but studies on the utilization of the robust yeast host, Saccharomyces cerevisiae, for alkane biosynthesis have been lacking. In this proof‐of‐principle study, we present the unprecedented engineering of S. cerevisiae for conversion of free fatty acids to alkanes. A fatty acid α‐dioxygenase from Oryza sativa (rice) was expressed in S. cerevisiae to transform C12–18 free fatty acids to C11–17 aldehydes. Co‐expression of a cyanobacterial aldehyde deformylating oxygenase converted the aldehydes to the desired alkanes. We demonstrated the versatility of the pathway by performing whole‐cell biocatalytic conversion of exogenous free fatty acid feedstocks into alkanes as well as introducing the pathway into a free fatty acid overproducer for de novo production of alkanes from simple sugar. The results from this work are anticipated to advance the development of yeast hosts for alkane production. Biotechnol. Bioeng. 2017;114: 232–237. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc.

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mentioning

confidence: 99%

Whole‐cell biocatalytic and de novo production of alkanes from free fatty acids in Saccharomyces cerevisiae

Foo

Susanto

Keasling

et al. 2016

Biotech & Bioengineering

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“…Environmental pH has a strong effect on the growth and fermentation property of S. cerevisiae 65-67 .…”

Section: Resultsmentioning

confidence: 99%

Ratiometric fluorescent pH-sensitive polymers for high-throughput monitoring of extracellular pH

Zhang

Kong

et al. 2016

RSC Adv.

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Extracellular pH has a strong effect on cell metabolism and growth. Precisely detecting extracellular pH with high throughput is critical for cell metabolism research and fermentation applications. In this research, a series of ratiometric fluorescent pH sensitive polymers are developed and the ps-pH-neutral is characterized as the best one for exculsive detection of extracellular pH. Poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) is used as the host polymer to increase the water solubility of the pH sensitive polymer without introducing cell toxicity. The fluorescent emission spectra from the polymeric sensor under excitation at the isosbestic point 455 nm possess two fluorescence peaks at 475 nm and 505 nm, which have different responding trends to pH. This enables the polymer to detect pH using fluorescent maxima at 475 nm and 505 nm (I475nm/I505nm) ratiometrically. The cell impermeability ensures the sensor can solely detect the environmental pH. The sensor is tested to detect the extracellular pH of bacteria or eukaryotic cells in high throughput assays using a microplate reader. Results showed that the pH sensor can be used for high throughput detection of extracellular pH with high repeatability and low photobleaching effect.

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“…To assess the enzymatic hydrolysis of alkali-thermal-pretreated soybean straw with 2 M sodium hydroxide, the pretreated biomass (10% (w/v)) was digested with different enzyme dose of Cellic CTec2 cellulase, from 10 to 50 FPU per gram of dry biomass in phosphate buffer (pH 6.0) for 72 h. The pH in the reaction media for the enzymatic digestion could affect the growth, metabolism, and transport in an ethanologenic strain for further ethanol fermentation [15]. Thus pH was fixed at 6.0 for the enzymatic biomass saccharification.…”

Section: Enzymatic Hydrolysis Of Soybean Strawmentioning

confidence: 99%

Evaluation of Alkali-Pretreated Soybean Straw for Lignocellulosic Bioethanol Production

Kim

2018

International Journal of Polymer Science

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Soybean straw is a renewable resource in agricultural residues that can be used for lignocellulosic bioethanol production. To enhance enzymatic digestibility and fermentability, the biomass was prepared with an alkali-thermal pretreatment (sodium hydroxide, 121°C, 60 min). The delignification yield was 34.1~53%, in proportion to the amount of sodium hydroxide, from 0.5 to 3.0 M. The lignin and hemicellulose contents of the pretreated biomass were reduced by the pretreatment process, whereas the proportion of cellulose was increased. Under optimal condition, the pretreated biomass consisted of 74.0±0.1% cellulose, 10.3±0.1% hemicellulose, and 10.1±0.6% lignin. During enzymatic saccharification using Cellic® CTec2 cellulase, 10% (w/v) of pretreated soybean straw was hydrolyzed completely and converted to 67.3±2.1 g/L glucose and 9.4±0.5 g/L xylose with a 90.9% yield efficiency. Simultaneous saccharification and fermentation of the pretreated biomass by Saccharomyces cerevisiae W303-1A produced 30.5±1.2 g/L ethanol in 0.5 L fermented medium containing 10% (w/v) pretreated biomass after 72 h. The ethanol productivity was 0.305 g ethanol/g dry biomass and 0.45 g ethanol/g glucose after fermentation, with a low concentration of organic acid metabolites. Also, 82% of fermentable sugar was used by the yeast for ethanol fermentation. These results show that the combination of alkaline pretreatment and biomass hydrolysate is useful for enhancing bioethanol productivity using delignified soybean straw.

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Effects of high medium pH on growth, metabolism and transport in Saccharomyces cerevisiae

Cited by 49 publications

References 34 publications

Whole‐cell biocatalytic and de novo production of alkanes from free fatty acids in Saccharomyces cerevisiae

Whole‐cell biocatalytic and de novo production of alkanes from free fatty acids in Saccharomyces cerevisiae

Ratiometric fluorescent pH-sensitive polymers for high-throughput monitoring of extracellular pH

Evaluation of Alkali-Pretreated Soybean Straw for Lignocellulosic Bioethanol Production

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