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In situ label-free imaging of hemicellulose in plant cell walls using stimulated Raman scattering microscopy

View Article: PubMed Central - PubMed

ABSTRACT

Background: Plant hemicellulose (largely xylan) is an excellent feedstock for renewable energy production and second only to cellulose in abundance. Beyond a source of fermentable sugars, xylan constitutes a critical polymer in the plant cell wall, where its precise role in wall assembly, maturation, and deconstruction remains primarily hypothetical. Effective detection of xylan, particularly by in situ imaging of xylan in the presence of other biopolymers, would provide critical information for tackling the challenges of understanding the assembly and enhancing the liberation of xylan from plant materials.

Results: Raman-based imaging techniques, especially the highly sensitive stimulated Raman scattering (SRS) microscopy, have proven to be valuable tools for label-free imaging. However, due to the complex nature of plant materials, especially those same chemical groups shared between xylan and cellulose, the utility of specific Raman vibrational modes that are unique to xylan have been debated. Here, we report a novel approach based on combining spectroscopic analysis and chemical/enzymatic xylan removal from corn stover cell walls, to make progress in meeting this analytical challenge. We have identified several Raman peaks associated with xylan content in cell walls for label-free in situ imaging xylan in plant cell wall.

Conclusion: We demonstrated that xylan can be resolved from cellulose and lignin in situ using enzymatic digestion and label-free SRS microscopy in both 2D and 3D. We believe that this novel approach can be used to map xylan in plant cell walls and that this ability will enhance our understanding of the role played by xylan in cell wall biosynthesis and deconstruction.

Electronic supplementary material: The online version of this article (doi:10.1186/s13068-016-0669-9) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus

Comparison of cellulose’s signature Raman peaks at 1095 and 1123 cm−1 in deacetylated corn stover cell walls with varying amounts of xylan content due to controlled xylanase digestion of xylan. a Raman spectra show little change. b, c The peak heights of 1095 and 1123 cm−1 in cell walls remain constant with varying amounts of cell wall xylan content. All spectrums are normalized. The gray traces indicate the standard deviations
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Fig3: Comparison of cellulose’s signature Raman peaks at 1095 and 1123 cm−1 in deacetylated corn stover cell walls with varying amounts of xylan content due to controlled xylanase digestion of xylan. a Raman spectra show little change. b, c The peak heights of 1095 and 1123 cm−1 in cell walls remain constant with varying amounts of cell wall xylan content. All spectrums are normalized. The gray traces indicate the standard deviations

Mentions: Figure 3 shows the comparison of cellulose-specific Raman bands from the deacetylated corn stover control and the cell wall samples with altered xylan contents. For comparison, these spectra are normalized by the lignin peak at 1604 cm−1. The two cellulose signature peaks, 1095  and 1123 cm−1, show similar shape for all the samples, albeit with significantly different xylan content (Fig. 3a). The peak heights of 1095 and 1123 cm−1 (baseline at 1050 cm−1) remain the same for the control and the enzyme-digested deacetylated corn stover cell wall (Fig. 3b, c). This result is an indication that the cellulose content in the cell wall is not affected by the xylanase treatments used for these samples.Fig. 3


In situ label-free imaging of hemicellulose in plant cell walls using stimulated Raman scattering microscopy
Comparison of cellulose’s signature Raman peaks at 1095 and 1123 cm−1 in deacetylated corn stover cell walls with varying amounts of xylan content due to controlled xylanase digestion of xylan. a Raman spectra show little change. b, c The peak heights of 1095 and 1123 cm−1 in cell walls remain constant with varying amounts of cell wall xylan content. All spectrums are normalized. The gray traces indicate the standard deviations
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5120481&req=5

Fig3: Comparison of cellulose’s signature Raman peaks at 1095 and 1123 cm−1 in deacetylated corn stover cell walls with varying amounts of xylan content due to controlled xylanase digestion of xylan. a Raman spectra show little change. b, c The peak heights of 1095 and 1123 cm−1 in cell walls remain constant with varying amounts of cell wall xylan content. All spectrums are normalized. The gray traces indicate the standard deviations
Mentions: Figure 3 shows the comparison of cellulose-specific Raman bands from the deacetylated corn stover control and the cell wall samples with altered xylan contents. For comparison, these spectra are normalized by the lignin peak at 1604 cm−1. The two cellulose signature peaks, 1095  and 1123 cm−1, show similar shape for all the samples, albeit with significantly different xylan content (Fig. 3a). The peak heights of 1095 and 1123 cm−1 (baseline at 1050 cm−1) remain the same for the control and the enzyme-digested deacetylated corn stover cell wall (Fig. 3b, c). This result is an indication that the cellulose content in the cell wall is not affected by the xylanase treatments used for these samples.Fig. 3

View Article: PubMed Central - PubMed

ABSTRACT

Background: Plant hemicellulose (largely xylan) is an excellent feedstock for renewable energy production and second only to cellulose in abundance. Beyond a source of fermentable sugars, xylan constitutes a critical polymer in the plant cell wall, where its precise role in wall assembly, maturation, and deconstruction remains primarily hypothetical. Effective detection of xylan, particularly by in situ imaging of xylan in the presence of other biopolymers, would provide critical information for tackling the challenges of understanding the assembly and enhancing the liberation of xylan from plant materials.

Results: Raman-based imaging techniques, especially the highly sensitive stimulated Raman scattering (SRS) microscopy, have proven to be valuable tools for label-free imaging. However, due to the complex nature of plant materials, especially those same chemical groups shared between xylan and cellulose, the utility of specific Raman vibrational modes that are unique to xylan have been debated. Here, we report a novel approach based on combining spectroscopic analysis and chemical/enzymatic xylan removal from corn stover cell walls, to make progress in meeting this analytical challenge. We have identified several Raman peaks associated with xylan content in cell walls for label-free in situ imaging xylan in plant cell wall.

Conclusion: We demonstrated that xylan can be resolved from cellulose and lignin in situ using enzymatic digestion and label-free SRS microscopy in both 2D and 3D. We believe that this novel approach can be used to map xylan in plant cell walls and that this ability will enhance our understanding of the role played by xylan in cell wall biosynthesis and deconstruction.

Electronic supplementary material: The online version of this article (doi:10.1186/s13068-016-0669-9) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus