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

Office, Frontiers Production

doi:10.3389/fbioe.2020.617204

Cited by 1 publication

(5 citation statements)

References 2 publications

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“…After 15 h of fermentation, when growth phase 2 started, the μ decreased possibly because of the nitrogen limitation. At this time, the C/N ratio was 26, the same C/N ratio was reported by Pinheiro et al (2020) for the onset of nitrogen limitation. Also, at this time, all the sugars except xylose were depleted and the strain started to consume the latter.…”

Section: Discussionsupporting

confidence: 83%

“…This strain also demonstrated the highest co-consumption rate (0.73 ± 0.02 g/gdw*h) during the first growth phase and the highest specific xylose consumption rate (0.22 ± 0.02 g/gdw*h). The specific xylose uptake rate measured in the current study was slightly lower than the highest rate (nitrogen-excess phase, 0.26 g/gdw*h) reported by Pinheiro et al (2020) where the same strain was cultivated in a minimal mineral medium using 70 gL –1 of xylose and C/N molar ratio of 80. Although R. toruloides CCT 7815 had the highest specific xylose consumption rate, the μ of this strain was very similar to the one found for L. starkeyi DSM 70295 grown on xylose ( Table 1 ).…”

Section: Discussioncontrasting

confidence: 82%

“…XR from S. stipitis can use both of the cofactors ( Verduyn et al, 1985 ), while the XR from K. marxianus is specific for NADPH ( Zhang et al, 2013 ). In silico analysis of the XR enzyme of R. toruloides NP11 showed that the enzyme could use either of the cofactors ( Pinheiro et al, 2020 ). Jagtap et al (2019) reported a promiscuous NADPH-dependent aldose reductase in R. toruloides IFO 0880 capable of using xylose and galactose as substrate.…”

Section: Discussionmentioning

confidence: 99%

“…There are a few reports of alternative pathways when XDH or XK are deficient or knocked out ( Seiboth et al, 2003 ; Jin et al, 2005 ). XK has either been not detected or has been present in low abundance in proteomics and transcriptomics analysis of xylose-grown R. toruloides CCT 7815 and IFO 0880 ( Pinheiro et al, 2020 ; Kim et al, 2021 ). An alternative pathway to PPP would be converting D-xylulose to D-ribulose-5-phosphate instead of D-xylulose-5-phosphate, and was recently proposed ( Kim et al, 2021 ).…”

Section: Discussionmentioning

confidence: 99%

“…Total lipids were determined gravimetrically. Carotenoids were extracted by the methodology described by Pinheiro et al (2020) . Concentrations of β-carotene, torulene, and torularhodin were determined using column 00F-4462-E0 Kinetex 2.6 μm C18 100 Å (Phenomenex, Torrance, United States) at 40°C.…”

Section: Methodsmentioning

confidence: 99%

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Screening and Growth Characterization of Non-conventional Yeasts in a Hemicellulosic Hydrolysate

Oliveira

Aborneva

Bonturi

et al. 2021

Front. Bioeng. Biotechnol.

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Lignocellulosic biomass is an attractive raw material for the sustainable production of chemicals and materials using microbial cell factories. Most of the existing bioprocesses focus on second-generation ethanol production using genetically modified Saccharomyces cerevisiae, however, this microorganism is naturally unable to consume xylose. Moreover, extensive metabolic engineering has to be carried out to achieve high production levels of industrially relevant building blocks. Hence, the use of non-Saccharomyces species, or non-conventional yeasts, bearing native metabolic routes, allows conversion of a wide range of substrates into different products, and higher tolerance to inhibitors improves the efficiency of biorefineries. In this study, nine non-conventional yeast strains were selected and screened on a diluted hemicellulosic hydrolysate from Birch. Kluyveromyces marxianus CBS 6556, Scheffersomyces stipitis CBS 5773, Lipomyces starkeyi DSM 70295, and Rhodotorula toruloides CCT 7815 were selected for further characterization, where their growth and substrate consumption patterns were analyzed under industrially relevant substrate concentrations and controlled environmental conditions in bioreactors. K. marxianus CBS 6556 performed poorly under higher hydrolysate concentrations, although this yeast was determined among the fastest-growing yeasts on diluted hydrolysate. S. stipitis CBS 5773 demonstrated a low growth and biomass production while consuming glucose, while during the xylose-phase, the specific growth and sugar co-consumption rates were among the highest of this study (0.17 h–1 and 0.37 g/gdw*h, respectively). L. starkeyi DSM 70295 and R. toruloides CCT 7815 were the fastest to consume the provided sugars at high hydrolysate conditions, finishing them within 54 and 30 h, respectively. R. toruloides CCT 7815 performed the best of all four studied strains and tested conditions, showing the highest specific growth (0.23 h–1), substrate co-consumption (0.73 ± 0.02 g/gdw*h), and xylose consumption (0.22 g/gdw*h) rates. Furthermore, R. toruloides CCT 7815 was able to produce 10.95 ± 1.37 gL–1 and 1.72 ± 0.04 mgL–1 of lipids and carotenoids, respectively, under non-optimized cultivation conditions. The study provides novel information on selecting suitable host strains for biorefinery processes, provides detailed information on substrate consumption patterns, and pinpoints to bottlenecks possible to address using metabolic engineering or adaptive evolution experiments.

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Section: Discussionsupporting

confidence: 83%

Section: Discussioncontrasting

confidence: 82%