| 1. |
- Almeida, João R.M., et al.
(författare)
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Physiological and Molecular Characterization of Yeast Cultures Pre-Adapted for Fermentation of Lignocellulosic Hydrolysate
- 2023
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Ingår i: Fermentation. - : MDPI AG. - 2311-5637. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Economically feasible bioethanol process from lignocellulose requires efficient fermentation by yeast of all sugars present in the hydrolysate. However, when exposed to lignocellulosic hydrolysate, Saccharomyces cerevisiae is challenged with a variety of inhibitors that reduce yeast viability, growth, and fermentation rate, and in addition damage cellular structures. In order to evaluate the capability of S. cerevisiae to adapt and respond to lignocellulosic hydrolysates, the physiological effect of cultivating yeast in the spruce hydrolysate was comprehensively studied by assessment of yeast performance in simultaneous saccharification and fermentation (SSF), measurement of furaldehyde reduction activity, assessment of conversion of phenolic compounds and genome-wide transcription analysis. The yeast cultivated in spruce hydrolysate developed a rapid adaptive response to lignocellulosic hydrolysate, which significantly improved its fermentation performance in subsequent SSF experiments. The adaptation was shown to involve the induction of NADPH-dependent aldehyde reductases and conversion of phenolic compounds during the fed-batch cultivation. These properties were correlated to the expression of several genes encoding oxidoreductases, notably AAD4, ADH6, OYE2/3, and YML131w. The other most significant transcriptional changes involved genes involved in transport mechanisms, such as YHK8, FLR1, or ATR1. A large set of genes were found to be associated with transcription factors (TFs) involved in stress response (Msn2p, Msn4p, Yap1p) but also cell growth and division (Gcr4p, Ste12p, Sok2p), and these TFs were most likely controlling the response at the post-transcriptional level.
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| 2. |
- Costa, Thales H.F., et al.
(författare)
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Demonstration-scale enzymatic saccharification of sulfite-pulped spruce with addition of hydrogen peroxide for LPMO activation
- 2020
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Ingår i: Biofuels, Bioproducts and Biorefining. - : Wiley. - 1932-104X .- 1932-1031. ; 14:4, s. 734-745
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Tidskriftsartikel (refereegranskat)abstract
- The saccharification of lignocellulosic materials like Norway spruce is challenging due to the recalcitrant nature of the biomass, and it requires optimized and efficient pretreatment and enzymatic hydrolysis processes to make it industrially feasible. In this study, we report successful enzymatic saccharification of sulfite-pulped spruce (Borregaard's BALI™ process) at demonstration scale, achieved through the controlled delivery of hydrogen peroxide (H2O2) for the activation of lytic polysaccharide monooxygenases (LPMOs) present in the cellulolytic enzyme preparation. We achieved 85% saccharification yield in 4 days using industrially relevant conditions – that is, an enzyme dose of 4% (w/w dry matter of substrate) of the commercial cellulase cocktail Cellic CTec3 and a substrate loading of 12% (w/w). Addition of H2O2 and the resulting controlled and high LPMO activity had a positive effect on the rate of saccharification and the final sugar titer. Clearly, the high LPMO activity was dependent on feeding the reactors with the LPMO co-substrate H2O2, as in situ generation of H2O2 from molecular oxygen was limited. These demonstration-scale experiments provide a solid basis for the use of H2O2 to improve enzymatic saccharification of lignocellulosic biomass at large industrial scale.
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| 3. |
- García-Hidalgo, Javier, et al.
(författare)
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Vanillin Production in pseudomonas : Whole-genome sequencing of pseudomonas sp. strain 9.1 and reannotation of pseudomonas putida CalA as a vanillin reductase
- 2020
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 86:6
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Tidskriftsartikel (refereegranskat)abstract
- Microbial degradation of lignin and its related aromatic compounds has great potential for the sustainable production of chemicals and bioremediation of contaminated soils. We previously isolated Pseudomonas sp. strain 9.1 from historical waste deposits (forming so-called fiber banks) released from pulp and paper mills along the Baltic Sea coast. The strain accumulated vanillyl alcohol during growth on vanillin, and while reported in other microbes, this phenotype is less common in wild-type pseudomonads. As the reduction of vanillin to vanil- lyl alcohol is an undesired trait in Pseudomonas strains engineered to accumulate vanillin, connecting the strain 9.1 phenotype with a genotype would increase the fundamental understanding and genetic engineering potential of microbial vanillin metabolism. The genome of Pseudomonas sp. 9.1 was sequenced and assembled. Annotation identified oxidoreductases with homology to Saccharomyces cerevisiae alcohol dehydrogenase ScADH6p, known to reduce vanillin to vanillyl alcohol, in both the 9.1 genome and the model strain Pseudomonas putida KT2440. Recombinant expression of the Pseudomonas sp. 9.1 FEZ21_09870 and P. putida KT2440 PP_2426 (calA) genes in Escherichia coli revealed that these open reading frames encode aldehyde reductases that convert vanillin to vanillyl alcohol, and that P. putida KT2440 PP_3839 encodes a coniferyl alcohol dehydrogenase that oxidizes coniferyl alcohol to coniferyl aldehyde (i.e., the function previ-ously assigned to calA). The deletion of PP_2426 in P. putida GN442 engineered to accumulate vanillin resulted in a decrease in by-product (vanillyl alcohol) yield from 17% to -1%. Based on these results, we propose the reannotation of PP_2426 and FEZ21_09870 as areA and PP_3839 as calA-II. IMPORTANCE Valorization of lignocellulose (nonedible plant matter) is of key interest for the sustainable production of chemicals from renewable resources. Lignin, one of the main constituents of lignocellulose, is a heterogeneous aromatic biopolymer that can be chemically depolymerized into a heterogeneous mixture of aromatic building blocks; those can be further converted by certain microbes into value-added aromatic chemicals, e.g., the flavoring agent vanillin. We previously isolated a Pseudomonas sp. strain with the (for the genus) unusual trait of vanil- lyl alcohol production during growth on vanillin. Whole-genome sequencing of the isolate led to the identification of a vanillin reductase candidate gene whose deletion in a recombinant vanillin-accumulating P. putida strain almost completely alleviated the undesired vanillyl alcohol by-product yield. These results represent an important step toward biotechnological production of vanillin from lignin using bacterial cell factories.
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| 4. |
- Nyman, Ulf, et al.
(författare)
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Revised Swedish guidelines on intravenous iodine contrast medium-induced acute kidney injury 2022: A summary
- 2023
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 64:5
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Forskningsöversikt (refereegranskat)abstract
- The Swedish Society of Uroradiology has revised their computed tomography (CT) guidelines regarding iodine contrast media-induced acute kidney injury (CI-AKI). They are more cautious compared to the European Society of Urogenital Radiology and the American College of Radiology since the actual risk of CI-AKI remains uncertain in patients with moderate to severe kidney damage due to a lack of prospective controlled studies and mainly based on retrospective propensity score-matched studies with low-grade evidence. Another source of uncertainty is the imprecision of glomerular filtration rate (GFR) estimating equations. However, randomized hydration studies indictae an upper limit risk of CI-AKI of about 5% for outpatients with a GFR in the range of 30-44 or 45-59 mL/min/1.73m(2) combined with multiple risk factors. Apart from GFR limits, the guideline also includes limits for systemic contrast medium exposure expressed in gram-iodine/GFR ratio.
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| 5. |
- Rodríguez-Varela, Ricardo, et al.
(författare)
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The genetic history of Scandinavia from the Roman Iron Age to the present
- 2023
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Ingår i: Cell. - : Elsevier. - 0092-8674 .- 1097-4172. ; 186:1, s. 32-46
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Tidskriftsartikel (refereegranskat)abstract
- We investigate a 2,000-year genetic transect through Scandinavia spanning the Iron Age to the present, based on 48 new and 249 published ancient genomes and genotypes from 16,638 modern individuals. We find regional variation in the timing and magnitude of gene flow from three sources: the eastern Baltic, the British-Irish Isles, and southern Europe. British-Irish ancestry was widespread in Scandinavia from the Viking period, whereas eastern Baltic ancestry is more localized to Gotland and central Sweden. In some regions, a drop in current levels of external ancestry suggests that ancient immigrants contributed proportionately less to the modern Scandinavian gene pool than indicated by the ancestry of genomes from the Viking and Medieval periods. Finally, we show that a north-south genetic cline that characterizes modern Scandinavians is mainly due to the differential levels of Uralic ancestry and that this cline existed in the Viking Age and possibly earlier.
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