Browsing by Autor "Eva Nordberg Karlsson"

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A novel glycoside hydrolase 43-like enzyme from Clostridium boliviensis is an endo-xylanase and a candidate for xylooligosaccharide production from different xylan substrates
(American Society for Microbiology, 2024) Daniel Martín Salas-Veizaga; Leonardo Roberto Rocabado-Villegas; Javier A. Linares‐Pastén; Elísabet Eik Guðmundsdóttir; Guðmundur Ó. Hreggviðsson; María Teresa Álvarez Aliaga; Patrick Adlercreutz; Eva Nordberg Karlsson
The genome of Clostridium boliviensis strain E-1 encodes a number of hypothetical enzymes, annotated as glycoside hydrolase-like but not classified in the Carbohydrate Active Enzyme Database (CAZy). A novel thermostable GH43-like enzyme is here characterized as an endo-β-xylanase of interest in the production of prebiotic xylooligosaccharides (XOs) from different xylan sources. CbE1Xyn43-l is a two-domain enzyme composed of a catalytic GH43-l domain and a CBM6 domain, producing xylotriose as main XO product. The enzyme has homologs in many related Clostridium strains which may indicate a similar function and be a previously unknown type of endo-xylanase in this evolutionary lineage of microorganisms.
A single residue affects the dynamics and shape of a tetrameric <scp>GH43</scp> β‐1,4‐<scp>d</scp>‐xylosidase from Levilactobacillus brevis<scp>DSM1269</scp>
(Wiley, 2025) Javier A. Linares‐Pastén; Reza Faryar; Sergio Torrez Álvarez; Khalil Albasri; Bashar Shuoker; Maher Abou Hachem; Derek T. Logan; Eva Nordberg Karlsson
Lignocellulosic materials (e.g., straw and bran) are gaining interest as feedstocks for the manufacture of higher value products, recognizing xylooligosaccharides (XOS) as interesting prebiotic compounds, and putting enzymes converting xylooligosaccharides into focus. In this work, we are investigating a XOS converting enzyme from the probiotic bacterium Levilactobacillus brevis (formerly Lactobacillus brevis). Growth of multiple L. brevis strains, recognized as probiotics, is promoted by the presence of XOS. This study elucidates the 3D structure of an intracellular L. brevis β-xylosidase, LbXyn43B from glycoside hydrolase family 43 (GH43), resolving it to 1.9 Å resolution. Functional analysis identified LbXyn43B as a mediator for XOS utilization in L. brevis DSM1269. The enzyme, featuring a 5-fold β-propeller fold typical of GH43, prefers short XOS substrates, notably β-1,4-xylobiose and β-1,4-xylotriose, aligning with its role in hydrolyzing internalized XOS. Intriguingly, crystallographic and size exclusion chromatographic evidence reveals LbXyn43B to be a tetramer, contrary to the dimeric structure previously reported in a closely related homolog from strain DSM20054. Despite sharing a high sequence identity (differing in only five residues), Thr274 in LbXyn43B within a subunit interface loop was found to influence the tetramer's shape. When mutated to Ala (the residue at the corresponding position in the homolog), the enzyme's apparent native molecular mass was impacted, resulting in a more compact oligomeric structure of slightly higher thermostability. Kinetic analysis and molecular dynamics simulations further suggest an effect of Thr274Ala substitution in modulating the accessibility of longer oligosaccharides, such as β-1,4-d-xylotetraose, to the active site.
Caloramator boliviensis sp. nov., a thermophilic, ethanol-producing bacterium isolated from a hot spring
(Microbiology Society, 2011) Carla Crespo; Tania Pozzo; Eva Nordberg Karlsson; María Teresa Álvarez; Bo Mattìasson
A novel moderately thermophilic, anaerobic, ethanol-producing bacterial strain, 45B(T), was isolated from a mixed sediment water sample collected from a hot spring at Potosi, Bolivia. The cells were straight to slightly curved rods approximately 2.5 µm long and 0.5 µm wide. The strain was Gram-stain-variable, spore-forming and monotrichously flagellated. Growth of the strain was observed at 45-65 °C and pH 5.5-8.0, with optima of 60 °C and pH 6.5. The substrates utilized by strain 45B(T) were xylose, cellobiose, glucose, arabinose, sucrose, lactose, maltose, fructose, galactose, mannose, glycerol, xylan, carboxymethylcellulose and yeast extract. The main fermentation product from xylose and cellobiose was ethanol (0.70 and 0.45 g ethanol per gram of consumed sugar, respectively). Acetate, lactate, propionate, carbon dioxide and hydrogen were also produced in minor quantities. 1,3-Propanediol was produced when glycerol-containing medium was supplemented with yeast extract. The major cellular fatty acids were anteiso-C(15:0), C(16:0), iso-C(16:0), C(15:1), iso-C(14:0), C(13:0) and C(14:0). The polar lipids diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an aminoglycolipid and 15 other unidentified lipids were predominant. The DNA G+C content of strain 45B(T) was 32.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequence similarity revealed that strain 45B(T) is located within the Gram-type positive Bacillus-Clostridium branch of the phylogenetic tree. On the basis of morphological and physiological properties and phylogenetic analysis, strain 45B(T) represents a novel species, for which the name Caloramator boliviensis sp. nov. is proposed; the type strain is 45B(T) (=DSM 22065(T)=CCUG 57396(T)).
Data on saponins, xylan and cellulose yield obtained from quinoa stalks after pressurized hot water extraction
(Elsevier BV, 2018) Alicia Gil‐Ramírez; Daniel Martín Salas-Veizaga; Carl Grey; Eva Nordberg Karlsson; Irene Rodríguez‐Meizoso; Javier A. Linares‐Pastén
Extraction of Glucuronoarabinoxylan from Quinoa Stalks (Chenopodium quinoa Willd.) and Evaluation of Xylooligosaccharides Produced by GH10 and GH11 Xylanases
(American Chemical Society, 2017) Daniel Martín Salas-Veizaga; Rodrigo Villagomez; Javier A. Linares‐Pastén; Cristhian Carrasco; María Teresa Álvarez; Patrick Adlercreutz; Eva Nordberg Karlsson
Byproducts from quinoa are not yet well explored sources of hemicellulose or products thereof. In this work, xylan from milled quinoa stalks was retrieved to 66% recovery by akaline extraction using 0.5 M NaOH at 80 °C, followed by ethanol precipitation. The isolated polymer eluted as a single peak in size-exclusion chromatography with a molecular weight of >700 kDa. Analysis by Fourier transform infrared spectroscopy and nuclear magnetic resonance (NMR) combined with acid hydrolysis to monomers showed that the polymer was built of a backbone of β(1 → 4)-linked xylose residues that were substituted by 4-O-methylglucuronic acids, arabinose, and galactose in an approximate molar ratio of 114:23:5:1. NMR analysis also indicated the presence of α(1 → 5)-linked arabinose substituents in dimeric or oligomeric forms. The main xylooligosaccharides (XOs) produced after hydrolysis of the extracted glucuronoarabinoxylan polymer by thermostable glycoside hydrolases (GHs) from families 10 and 11 were xylobiose and xylotriose, followed by peaks of putative substituted XOs. Quantification of the unsubstituted XOs using standards showed that the highest yield from the soluble glucuronoarabinoxylan fraction was 1.26 g/100 g of xylan fraction, only slightly higher than the yield (1.00 g/100 g of xylan fraction) from the insoluble fraction (p < 0.05). No difference in yield was found between reactions in buffer or water (p > 0.05). This study shows that quinoa stalks represent a novel source of glucuronoarabinoxylan, with a substituent structure that allowed for limited production of XOs by GH10 or GH11 enzymes.
Integrated process for sequential extraction of saponins, xylan and cellulose from quinoa stalks (Chenopodium quinoa Willd.)
(Elsevier BV, 2018) Alicia Gil‐Ramírez; Daniel Martín Salas-Veizaga; Carl Grey; Eva Nordberg Karlsson; Irene Rodríguez‐Meizoso; Javier A. Linares‐Pastén
Production of a lipolytic enzyme originating from Bacillus halodurans LBB2 in the methylotrophic yeast Pichia pastoris
(Springer Science+Business Media, 2005) Santosh Ramchuran; Virginia A. Vargas; Rajni Hatti‐Kaul; Eva Nordberg Karlsson