Referee 2’s Review (Hossam Ashour, Ph.D.):

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N.B. These are the comments made by the referee when reviewing an earlier version of this paper. Prior to publication the manuscript has been revised in light of these comments and to address other editorial requirements.
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The manuscript of Bharadwaj et al tested the importance of N-terminal valine residue in stabilizing GH10 xylanase from Bacillus sp under poly-extreme conditions. The study was carefully designed but not so well presented. The manuscript has numerous spelling and grammatical mistakes that need to be fixed.

I will point out a few of these mistakes. However, the authors need to closely examine and revise their manuscript. I would suggest consulting a native english speaker and performing a simple spell check before re-sending the manuscript!

1- Abstract: change it's to its (change everywhere)
CD in the abstract needs to be spelled out.
last line of abstract: and IS therefore of major significance

2-Introduction: Line 6: Change role into roles
The authors mention that the surface residues of a protein are generally tolerant to substitution, What do the authors mean by "tolerant to substitution". To me "tolerant to substitution" is equivalent to "cannot be substituted".

Last paragraph of introduction: poly-extreme and not poly-extree

3-Results:

First paragraph: secretary sequence??? Probably the authors mean secretory sequence?

Mass spec : Please spell out.

The "linker region" also gets processed (change get into gets)

Second paragraph: full of grammatical mistakes. Re-write

Third paragraph: "Furthermore, it also increases the hydrophobicity" till the end of the paragraph, re-write (numerous grammatical mistakes)

P. 7: and thus demonstrated (not demonstrate)

Thermally most unstable ?? correct it.

Last paragraph of results.
proportionally to its molecular weight?? please correct the grammer.

V1A and V1 mutants were (and not are) relatively more sensitive

Activity of all (and not al)

Might indicate (not be indicating) irreversible structural changes...

4-Discussion: Second paragraph is too long, break down.
thereby (and not there by)

were mutated (and not were mutate)

Fourth paragraph: Furthermore (and not Further)

compared to less stable variants (and not variant)

6th paragraph: broad-spectrum nature?? Fix

have shown (and not have showed)

The whole discussion section needs to be revised grammatically. It is also redundant and inconclusive. The authors need to focus on the main points and main message of the paper in the discussion section.

5- Table 1: Protinase? Succeptable?

Can the authors speculate on the role of N-terminal valine residue in other extreme conditions? What if there was a combination of extreme conditions? Will the Val1 still be helpful?

The very poor presentation of the manuscript depreciated the rigorous work done and gave hard time for the reviewer in following up with the experiments.

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Hossam M Ashour, Ph.D.
Department of Microbiology and Immunology
Faculty of Pharmacy
Cairo University
Egypt 11562