Combining metabolic evolution and systematic fed-batch optimization for efficient single-cell oil production from sugarcane bagasse

Unrean, Pornkamol; Khajeeram, Sutamat; Champreda, Verawat

doi:10.1016/j.renene.2017.04.018

Cited by 14 publications

(7 citation statements)

References 32 publications

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“…This microorganism is a natural producer of lipids (microbial oil) and high-value compounds, such as carotenoids and enzymes for pharma and chemical industries (L-phenylalanine ammonia-lyase and D-amino acid oxidase) ( Park et al, 2017 ). The microbial oil, which is primarily composed of triacylglycerides (TAGs), is a potential raw material for oleochemicals that can be used as biodiesel, cosmetics, and coatings as well as a replacement of vegetable oil in fish feed ( Unrean et al, 2017 ; Blomqvist et al, 2018 ; Yang et al, 2018 ). Carotenoids are important molecules for different industries, such as the food, chemical, pharmaceutical and cosmetics industries.…”

Section: Introductionmentioning

confidence: 99%

Xylose Metabolism and the Effect of Oxidative Stress on Lipid and Carotenoid Production in Rhodotorula toruloides: Insights for Future Biorefinery

Pinheiro

Bonturi

Belouah

et al. 2020

Front. Bioeng. Biotechnol.

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The use of cell factories to convert sugars from lignocellulosic biomass into chemicals in which oleochemicals and food additives, such as carotenoids, is essential for the shift toward sustainable processes. Rhodotorula toruloides is a yeast that naturally metabolises a wide range of substrates, including lignocellulosic hydrolysates, and converts them into lipids and carotenoids. In this study, xylose, the main component of hemicellulose, was used as the sole substrate for R. toruloides, and a detailed physiology characterisation combined with absolute proteomics and genome-scale metabolic models was carried out to understand the regulation of lipid and carotenoid production. To improve these productions, oxidative stress was induced by hydrogen peroxide and light irradiation and further enhanced by adaptive laboratory evolution. Based on the online measurements of growth and CO 2 excretion, three distinct growth phases were identified during batch cultivations. Majority of the intracellular flux estimations showed similar trends with the measured protein levels and demonstrated improved NADPH regeneration, phosphoketolase activity and reduced β-oxidation, correlating with increasing lipid yields. Light irradiation resulted in 70% higher carotenoid and 40% higher lipid content compared to the optimal growth conditions. The presence of hydrogen peroxide did not affect the carotenoid production but culminated in the highest lipid content of 0.65 g/g DCW. The adapted strain showed improved fitness and 2.3-fold higher carotenoid content than the parental strain. This work presents a holistic view of xylose conversion into microbial oil and carotenoids by R. toruloides, in a process toward renewable and cost-effective production of these molecules.

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Section: Introductionmentioning

confidence: 99%

Xylose Metabolism and the Effect of Oxidative Stress on Lipid and Carotenoid Production in Rhodotorula toruloides: Insights for Future Biorefinery

Pinheiro

Bonturi

Belouah

et al. 2020

Front. Bioeng. Biotechnol.

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“…The transition towards a bioeconomy requires novel processes for chemical, material, and liquid fuel production that use sustainable substrates, have improved life cycle assessments, and require less energy to produce. Recent developments have drawn attention to the production of oleochemicals, i.e., chemicals derived from plant oils and animal fats, as attractive alternative feedstocks in the petrochemical industry (Adrio 2017;Unrean et al 2017;Yang et al 2018). Oleochemicals comprise a wide range of molecules that can be used as biofuels (fatty acid methyl esters, i.e., biodiesel), cosmetics, plastics, surface coatings, surfactants, lubricants, and paints, among others.…”

Section: Introductionmentioning

confidence: 99%

“…The global demand for fatty acids and fatty alcohols in the year 2020 is expected to reach over 10 Mt, and the projected growth of global biodiesel production is also driving the need to increase the production of fatty acid methyl esters (Yang et al 2018). Microbial lipids are one fatty acid source that is also considered to be a potential feedstock for oleochemical production (Unrean et al 2017). Microbial oils, also termed single cell oils (SCOs), are mostly composed of triacylglycerides (TAGs), and are produced by oleaginous bacteria, algae, yeasts, and molds which are capable of accumulating more than 20% of their dry biomass as lipids (Ratledge and Wynn 2002).…”

Section: Introductionmentioning

confidence: 99%

C/N ratio and carbon source-dependent lipid production profiling in Rhodotorula toruloides

Lopes

Bonturi

Kerkhoven

et al. 2020

Appl Microbiol Biotechnol

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Microbial oils are lipids produced by oleaginous microorganisms, which can be used as a potential feedstock for oleochemical production. The oleaginous yeast Rhodotorula toruloides can co-produce microbial oils and high-value compounds from lowcost substrates, such as xylose and acetic acid (from hemicellulosic hydrolysates) and raw glycerol (a byproduct of biodiesel production). One step towards economic viability is identifying the best conditions for lipid production, primarily the most suitable carbon-to-nitrogen ratio (C/N). Here, we aimed to identify the best conditions and cultivation mode for lipid production by R. toruloides using various low-cost substrates and a range of C/N ratios (60, 80, 100, and 120). Turbidostat mode was used to achieve a steady state at the maximal specific growth rate and to avoid continuously changing environmental conditions (i.e., C/N ratio) that inherently occur in batch mode. Regardless of the carbon source, higher C/N ratios increased lipid yields (up to 60% on xylose at a C/N of 120) but decreased the specific growth rate. Growth on glycerol resulted in the highest specific growth and lipid production (0.085 g lipids/gDW*h) rates at C/Ns between 60 and 100. We went on to study lipid production using glycerol in both batch and fed-batch modes, which resulted in lower specific lipid production rates compared with turbisdostat, however, fed batch is superior in terms of biomass production and lipid titers. By combining the data we obtained in these experiments with a genome-scale metabolic model of R. toruloides, we identified targets for improvements in lipid production that could be carried out either by metabolic engineering or process optimization. Keywords Rhodotorula toruloides. Microbial oil. Biorefineries. Genome-scale metabolic model. Flux balance analysis. Carbon to nitrogen ratio. Alternative substrates Helberth Júnnior Santos Lopes and Nemailla Bonturi contributed equally to this work.

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“…However, the lipid content and productivity of the most promising microbial cell factories, oleaginous yeasts, are still far below the requirements of industrial applications when lignocellulose is used (Slininger et al, 2016). Various methods had been tried to obtain high lipid producing oleaginous yeasts, including conventional mutations, metabolic engineering modifications, or adaptive evolution, but only limited progress were obtained (Beopoulos et al, 2008; Blazeck et al, 2014; Diaz et al, 2018; Unrean et al, 2017; Yamada et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Ultra‐centrifugation force in adaptive evolution changes the cell structure of oleaginous yeast Trichosporon cutaneum into a favorable space for lipid accumulation

Liu

Jin

et al. 2022

Biotech & Bioengineering

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Microbial lipid production from lignocellulose biomass provides an essential option for sustainable and carbon‐neutral supply of future aviation fuels, biodiesel, as well as various food and nutrition products. Oleaginous yeast is the major microbial cell factory but its lipid‐producing performance is far below the requirements of industrial application. Here we show an ultra‐centrifugation fractionation in adaptive evolution (UCF) of Trichosporon cutaneum based on the minor cell density difference. The lightest cells with the maximum intracellular lipid content were isolated by ultra‐centrifugation fractionation in the long‐term adaptive evolution. Significant changes occurred in the cell morphology with a fragile cell wall wrapping and enlarged intracellular space (two orders of magnitude increase in cell size). Complete and coordinate assimilations of all nonglucose sugars derived from lignocellulose were triggered and fluxed into lipid synthesis. Genome mutations and significant transcriptional regulations of the genes responsible for cell structure were identified and experimentally confirmed. The obtained T. cutaneum MP11 cells achieved a high lipid production of wheat straw, approximately five‐fold greater than that of the parental cells. The study provided an effective method for screening the high lipid‐containing oleaginous yeast cells as well as the intracellular products accumulating cells in general.

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Combining metabolic evolution and systematic fed-batch optimization for efficient single-cell oil production from sugarcane bagasse

Cited by 14 publications

References 32 publications

Xylose Metabolism and the Effect of Oxidative Stress on Lipid and Carotenoid Production in Rhodotorula toruloides: Insights for Future Biorefinery

Xylose Metabolism and the Effect of Oxidative Stress on Lipid and Carotenoid Production in Rhodotorula toruloides: Insights for Future Biorefinery

C/N ratio and carbon source-dependent lipid production profiling in Rhodotorula toruloides

Ultra‐centrifugation force in adaptive evolution changes the cell structure of oleaginous yeast Trichosporon cutaneum into a favorable space for lipid accumulation

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