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