Identification of WxL and S-Layer Proteins from Lactobacillus brevis with the Ability to Bind Cellulose and Xylan
Round 1
Reviewer 1 Report
The authors should provide the original files for WB data. They submitted the edited data. Uncropped full membrane images have to be provided
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors address a topic including xylanase, which releases xylo-oligosaccharides from dietary xylan. They stimulate growth of the gut bacteria lactobacilli. Many lactobacilli adhere to dietary fibers, which may facilitate assimilation of xylo-oligosaccharides and help them gain competence in the gut. The authors indicate that in wheat arabinoxylan supplemented with a xylanase, the identification of genes encoding four putative cell surface WxL proteins (Lb630, Lb631, Lb632, and Lb635) and one S-layer protein (Lb1325) with either cellulose- or xylan-binding ability are key. Their analysis revealed three aromatic residues (F30, W61, and W156) that might be involved in interaction of the protein with cellulose. Homology search in the genome of Enterococcus faecium identified three WxL proteins with conserved counterparts of these three aromatic residues and they were also discovered to be able to bind cellulose and xylan. The authors conclude that there is a specific role of the cell surface WxL and S-layer proteins in assisting cell adhesion of L. brevis to plant cell wall polysaccharides.
In my opinion, it is a good study, but it looks like more a pilot study and the conclusions are substantially very speculative. The experiments have been performed correctly, but the interpretation is too emphatic.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
Thank you very much to the Editor of International Journal of Molecular Sciences for allowing me to review the paper entitled ‘Identification of WxL and S-layer proteins from Lactobacillus brevis with the ability to bind cellulose and xylan’. The present study suggests a role of the cell surface WxL and S-layer proteins in assisting cell adhesion of Lactobacillus brevis to plant cell wall polysaccharides.
Major comments:
The paper is based on the relatively rich literature (27 items), but only 59% of used publications are from the last TEN years. Please introduce some new items.
Lack of LIMITATIONS of study (at the end of DISCUSSION).
Minor comments:
INSTEAD OF:
Then cells were washed twice with a PC buffer (10 mM citric acid-Na2HPO4, pH 5.0, 75 mM NaCl) and suspended in the same buffer to an OD600 of 0.7.
SHOULD BE:
Then cells were washed twice with a PC buffer (10 mmol/L citric acid-Na2HPO4, pH 5.0, 75 mmol/L NaCl) and suspended in the same buffer to an OD600 of 0.7.
INSTEAD OF:
The soluble extract was passed through a Ni-affinity column resin and the resin was washed with a binding buffer (20 mM Tris-HCl, pH 7.4, 500 mM NaCl). The bound proteins were eluted using the elution buffer (20 mM Tris-HCl, pH 7.4, 500 mM NaCl, 500 mM imidazole). The fractions with pure proteins were pooled, concentrated, and changed to a protein storage buffer (50 mM Tris-HCl, pH 7.4, 150 mM NaCl).
SHOULD BE:
The soluble extract was passed through a Ni-affinity column resin and the resin was washed with a binding buffer (20 mmol/L Tris-HCl, pH 7.4, 500 mmol/L NaCl). The bound proteins were eluted using the elution buffer (20 mmol/L Tris-HCl, pH 7.4, 500 mmol/L NaCl, 500 mmol/L imidazole). The fractions with pure proteins were pooled, concentrated, and changed to a protein storage buffer (50 mmol/L Tris-HCl, pH 7.4, 150 mmol/L NaCl).
Author Response
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Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
I appreciate the raw files provided by the authors. In general, the paper is OK and can be published after some revisions. The most important issue, in my opinion, is that the authors do not demonstrate the topography of cells attachment to the cellulose fibres. Though technically it is very easy to isolate the fibres and produce SEM and/or AFM images of the cells attached to these fibres. This would provide some insights on the cell surface structure in relation to attachment.
- What was the size distribution of cellulose and xylan particles? How stable the suspension was?
- Please provide additional experimental details, e.g. for SDS-PAGE which equipment was used, voltage, time, imaging instrumentation, etc.
- Additional references related to this study are suggested for citation:
- https://doi.org/10.1111/1751-7915.13584
- https://doi.org/10.1155/2017/9869145
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
The manuscript was succinctly revised with substantially a paragraph added in the discussion.
Author Response
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Author Response File: Author Response.docx
Round 3
Reviewer 2 Report
The manuscript is of poor quality and despite some improvements it does not reach the level of IJMS.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
