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Table 1 Summary of reported structural changes in lignocellulosic substrates caused by swollenin preparations obtained through different strategies of protein expression and production

From: Functional characterization of the native swollenin from Trichoderma reesei: study of its possible role as C1 factor of enzymatic lignocellulose conversion

Native source/produced in/purification/aMm Substrates Experimental setup; employed methods Effects Ref.
T. reesei/S. cerevisiae/CS/~75 kDa Mercerized cotton fibers 0.25 µgSwo/gsubstrate, 25 °C, 4 h; light microscopy Local disruption of cotton fibers, no release of sugars [18]
T. reesei/S. cerevisiae/CS/~75 kDa Whatman No. 3 filter paper 5 mL CS/filter paper strip, room temperature, 15 min; paper strength test Reduction of tensile strength and average peak load (15–20 %) [18]
T. reesei/A. niger/AC/~80–95 kDa Valonia sp. cell wall fragments 10 µgSwo/gsubstrate, 45 °C, 48 h; AFM, light microscopy Partial disintegration to isolated fibers, no release of sugars [18]
A. fumigatus/A. oryzae/AC/~85 kDa Avicel PH-101, filter paper (603 cellulose thimbles) 0.8 µgSwo/mgAvicel, 8 µgSwo/mgfilter paper, 40 °C, 72 h; light microscopy, visual examination Avicel PH-101 particle size reduction (~50 %), effect is pH- and temperature-dependent; complete disruption of filter paper, no release of sugars [34]
T. reesei/K. lactis/IMAC/~100 kDa Whatman No. 1 filter paper, α-cellulose, Avicel PH-101, sigmacell 101 20 µgSwo/mgsubstrate, 45 °C, 48 h; XRD, laser diffraction Reduction of CrI (~10 up to 22 %) and particle size (up to ~30 %) was observed for all substrates except Sigmacell [37]
T. reesei/K. lactis/IMAC/~100 kDa Whatman No. 1 filter paper 20 µgSwo/mgsubstrate, 45 °C, 48 h; SEM, photography Deagglomeration of filter paper (reduction of particle size and count); SEM showed an increased surface roughness; no swelling was observed [37]
T. asperellum/E. coli/refolding, AC/~35–50 kDa Avicel PH-101 5 µgSwo/mgsubstrate, 50 °C, 91 h; light microscopy Partial disruption of Avicel PH-101 particles [38]
T. pseudokoningii/A. niger/HIC/~75 kDa Avicel PH-101, filter paper 5–20 µgSwo/mgAvicel, 0.5–2 µgSwo/mgfilter paper, 40 °C, 48–72 h; light microscopy, XRD No effects were observed by applying light microscopy; CrI was increased (88–90 %) [40]
T. reesei/T. reesei/IMAC, IE/n.a. Mercerized cotton fibers 10 µgSwo/mgsubstrate, 50 °C, overnight; CBM adsorption assay, SEM Available surface for CBMs was increased (~38 %); SEM showed a smoothed surface upon TrSwo1 treatment [41]
T. reesei/E. coli and N. tabacum/CS/n.a. Mercerized cotton fibers 0.2–2 µgSwo/mgsubstrate, 37 °C or 50 °C, 8 h; phase contrast microscopy Fiber expansion, inner fiber structure was altered independent of the TrSwo1 source [28]
P. oxalicum/T. reesei/precipitation, IMAC/~90 kDa Avicel PH-101 4 µgSwo/mgsubstrate, 50 °C, 48 h; light microscopy, protein binding assay Partial disruption of Avicel PH-101 particles; B max for cellulases was increased (~20 %) [39]
T. reesei/T. reesei/IMAC, IE/n.a. Dissolving pulp, various lignocellulosic pulps 50 µgSwo/mgsubstrate, 50 °C, overnight; high-resolution fiber quality analyzer Fragmentation was observed to a low extent for dissolving pulp fibers but not for lignocellulosic pulps [42]
Orpinomyces sp. strain C1A/E. coli/refolding, IMAC/~67 kDa Cotton fibers 0.25–5 µgSwo/mgsubstrate, 39 °C, 12 h; ESEM, Congo red cotton assay Average cotton fiber width was increased (~56 %); dye adsorption was increased (CAE ~0.4 for 5 µgSwo/mgsubstrate) [78]
  1. aMm apparent molecular mass, CS enriched culture supernatant, AC affinity chromatography, IMAC immobilized metal adsorption chromatography (via His-tag), HIC hydrophobic interaction chromatography, IE ion exchange chromatography, n.a. not available