Evolutionary Engineering of Two Robust Brazilian Industrial Yeast Strains for Thermotolerance and Second-Generation Biofuels

Mélo, Allan Henrique Félix de; Lopes, Alberto Moura Mendes; Dezotti, Nicole; Santos, Isabella Laporte; Teixeira, Gleidson Silva; Goldbeck, Rosana

doi:10.1089/ind.2019.0031

Cited by 13 publications

(7 citation statements)

References 40 publications

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“…Under anaerobic conditions, the pyruvate is metabolised to equimolar quantities of acetaldehyde and thence to ethanol and CO 2 and the recycling of NAD + . The industrial production of ethanol uses highly adapted yeast strains that can withstand the stresses imposed by large-scale bioreactor cultivation [ 21 , 22 ], including temperature [ 23 ], pH [ 24 ], the presence of metabolic inhibitors from treated plant biomass [ 25 ] and the accumulation of ethanol in the medium [ 26 ], such that sugar to ethanol conversion can be as high as 90% and ethanol concentrations of 20% readily achieved [ 27 ].…”

Section: Alcohol Biofuelsmentioning

confidence: 99%

Microbial pathways for advanced biofuel production

Love

2022

Biochemical Society Transactions

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Decarbonisation of the transport sector is essential to mitigate anthropogenic climate change. Microbial metabolisms are already integral to the production of renewable, sustainable fuels and, building on that foundation, are being re-engineered to generate the advanced biofuels that will maintain mobility of people and goods during the energy transition. This review surveys the range of natural and engineered microbial systems for advanced biofuels production and summarises some of the techno-economic challenges associated with their implementation at industrial scales.

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Section: Alcohol Biofuelsmentioning

confidence: 99%

Microbial pathways for advanced biofuel production

Love

2022

Biochemical Society Transactions

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“…As the saccharification rate increases at elevated temperatures, thermotolerant yeasts which can survive and ferment at higher temperatures than S. cerevisiae have been identified as promising candidates for SSF processes [ 19 , 27 , 28 ]. Two thermotolerant yeasts that are well-suited for this application include Kluyveromyces marxianus [ 29 – 31 ] and Ogataea ( Hansenula ) polymorpha [ 32 , 33 ], both of which can naturally ferment glucose into ethanol at high yields.…”

Section: Introductionmentioning

confidence: 99%

Cellulosic biofuel production using emulsified simultaneous saccharification and fermentation (eSSF) with conventional and thermotolerant yeasts

Hoffman

Álvarez

Alfassi

et al. 2021

Biotechnol Biofuels

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Background Future expansion of corn-derived ethanol raises concerns of sustainability and competition with the food industry. Therefore, cellulosic biofuels derived from agricultural waste and dedicated energy crops are necessary. To date, slow and incomplete saccharification as well as high enzyme costs have hindered the economic viability of cellulosic biofuels, and while approaches like simultaneous saccharification and fermentation (SSF) and the use of thermotolerant microorganisms can enhance production, further improvements are needed. Cellulosic emulsions have been shown to enhance saccharification by increasing enzyme contact with cellulose fibers. In this study, we use these emulsions to develop an emulsified SSF (eSSF) process for rapid and efficient cellulosic biofuel production and make a direct three-way comparison of ethanol production between S. cerevisiae, O. polymorpha, and K. marxianus in glucose and cellulosic media at different temperatures. Results In this work, we show that cellulosic emulsions hydrolyze rapidly at temperatures tolerable to yeast, reaching up to 40-fold higher conversion in the first hour compared to microcrystalline cellulose (MCC). To evaluate suitable conditions for the eSSF process, we explored the upper temperature limits for the thermotolerant yeasts Kluyveromyces marxianus and Ogataea polymorpha, as well as Saccharomyces cerevisiae, and observed robust fermentation at up to 46, 50, and 42 °C for each yeast, respectively. We show that the eSSF process reaches high ethanol titers in short processing times, and produces close to theoretical yields at temperatures as low as 30 °C. Finally, we demonstrate the transferability of the eSSF technology to other products by producing the advanced biofuel isobutanol in a light-controlled eSSF using optogenetic regulators, resulting in up to fourfold higher titers relative to MCC SSF. Conclusions The eSSF process addresses the main challenges of cellulosic biofuel production by increasing saccharification rate at temperatures tolerable to yeast. The rapid hydrolysis of these emulsions at low temperatures permits fermentation using non-thermotolerant yeasts, short processing times, low enzyme loads, and makes it possible to extend the process to chemicals other than ethanol, such as isobutanol. This transferability establishes the eSSF process as a platform for the sustainable production of biofuels and chemicals as a whole.

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“…A significant part of the production costs of both ethanol and SCO refers to the substrate cost suggesting that a choice of a low-cost material as substrate, such as a carbon-rich agro-industrial residue, is crucial for the process sustainability (Dourou et al, 2016; Osorio-González et al, 2019; Sarris et al, 2013). Moreover, new strategies using microorganisms derived after genetic engineering and/or adaptive laboratory evolution approaches, used to increase the efficiency of substrate assimilation and metabolite production, can contribute to the success of the process (da Silveira et al, 2020; Daskalaki et al, 2019; De Melo et al, 2020; Dourou et al, 2018; Li et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Bioconversion of pomegranate residues into biofuels and bioactive lipids

Dourou¹,

Economou

Aggeli

et al. 2021

Preprint

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Pomegranate residues (PRs) (i.e. the solid residues remaining after juice extraction), generated currently in abundance in Greece, contain a variety of carbon sources and therefore can be regarded as a potential feedstock for chemical and biotechnological processes rather than as waste materials. In the current project, the polysaccharides contained in PRs were extracted and hydrolyzed in a one-step process without the use of chemical reagents and the resulting broth was used as substrate in biotechnological applications, including ethanol and single cell oil (SCO) production. The yeasts Meyerozyma guilliermondii, Scheffersomyces coipomoensis, Sugiyamaella paludigena and especially Saccharomyces cerevisiae, were able to efficiently convert PR derived reducing sugars into bioethanol. Ethanol production under anaerobic conditions ranged from 3.6 to 12.5 g/L. In addition, the oleaginous yeasts Lipomyces lipofer and Yarrowia lipolytica as well as M. guilliermondii, S. coipomoensis and S. paludigena were tested for their ability to accumulate lipids suitable as feedstock for biodiesel production. Lipids were accumulated at concentrations up to 18% and were rich in palmitic acid (C16:0) and oleic acid (C18:1). Finally, the oleaginous fungus Cunnichamella echinulata was cultivated on PR based solid substrates for γ-linolenic acid (GLA) production. The fermented bio-products (i.e. fermented substrate plus fungal mycelia) contained up to 4.8 mg GLA/g of dry weight. Phenolic removal (up to 30%) was achieved by several of the above mentioned microorganisms, including C. echinulata, L. lipofer, M. guilliermondii, S. paludigena and Y. lipolytica. We conclude that PRs can be used as a raw material for microbial growth, ethanol and SCO production, which is of economic and environmental importance.

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Evolutionary Engineering of Two Robust Brazilian Industrial Yeast Strains for Thermotolerance and Second-Generation Biofuels

Cited by 13 publications

References 40 publications

Microbial pathways for advanced biofuel production

Microbial pathways for advanced biofuel production

Cellulosic biofuel production using emulsified simultaneous saccharification and fermentation (eSSF) with conventional and thermotolerant yeasts

Bioconversion of pomegranate residues into biofuels and bioactive lipids

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