Silica Wort Supplementation as an Alternative for Yeast Stress Relief on Corn Ethanol Production with Cell Recycling
, Rafael Soares Douradinho 1, Pietro Mendes Santis Sica 2, Layna Amorim Mota 3, Alana Uchôa Pinto 1, Tamires Marques Faria 1 and Antonio Sampaio Baptista 1Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Authors, Thank you for the chance to read such an interesting manuscript concerning supporting yeast during HGV technologies of starch fermentation.
In my opinion there are minor mistakes that should be improved before publication:
First of all - please check the journal demands if it is possible to place the materials and methods first, before the results and discussion- in my opinion, such paper arrangement is more "ergonomic" to the potential reader.
Below are the listed specific places where some improvements should be made:
Line 129, according to the p-values, it seems to me that if p<0,05, the differences are statistically significant; when p>0,05, there are no significant differences; it should also be clarified in lines 144 and 147 since the authors mention that it was a considerable difference and then they state that for the exact p values(below 0,05) there was no statistical difference)
In Materials and Methods: what was the total fermentation time of T1-T3 samples per cycle, and why were 5 cycles evaluated? Was the feed-batch mode used for all samples or only as an option?
Line 401-406 The enzymatic preparation names/trademarks should be added since the specific preparations may differ with their enzymatic activity.
Line 407—The authors should add the reasoning behind why the solids after the hydrolysis were removed before fermentation. These solids are left in industrial technologies since they contain some unhydrolysed dextrins, allowing the hydrolysis to proceed even during fermentation. However, it is much slower because of the lower-than-optimal temperatures.
Line 425 5 replications are the same as cycle?
Line 433—Was the biomass recycled, or was the new 15g/L dose of fresh yeast added for each cycle?
Line 440 – why was the feeding process 63.75h? Or maybe this is the range of 63-75h?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsComments and Suggestions for Authors
The paper presents a study investigating the impact of silica Wort as a stressor for yeast in the production of ethanol from corn. This manuscript is suitable for publication in the Stresses Journal. Nevertheless, the manuscript still presents some issues that require attention.
Here are my comments and suggestions.
1. It would be beneficial to include more recent references and information about this subject in the introduction section.
2. It is recommended that the following sentence be replaced with a new reference: "This program aims to promote technological innovation in biofuel production and aligns with the international commitments made by Brazil at the 2015 Climate Change Conference (COP21)".
3. Please replace the sentence presented at line 510, "….comparison at a significance level of 5% (p < 0.05)," with , "….comparison at a significance level of 95% (p < 0.05)."
4. For all equipment referenced in the manuscript, please provide the following details: name, manufacturer, and country of production.
5. Please provide a number for each equation used.
6. Please complete the sentence on line 401, which reads, “of water with pH adjusted to 5.8,” with the solution of XXX, conc used. The sentence present on line 468, "Glucose, fructose, and glycerol concentrations were determined from 1 mL samples of wort and wine," should be reformulated. Please provide further details about the method used.
8. The method used to reduce sugars should be detailed, as the results are given but the method is missing from the material and methods section.
9. The method used for trehalose analysis should be detailed.
10. The first subchapter from the material and methods section should be titled Chemicals and reagents used and please provide information about producer, etc.
11. Please provide a detailed account of the novelty of this work in comparison with existing information in the literature.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript may be accepted for publication after completion with the following information:
Introduction
Line 66 - Explain please why was silica used in the amount of 500 mg/l?
Line 401 α-amylase enzyme – give more information on activity of enzyme, producer, country
Line 406 amyloglucosidase enzyme - note as above
Results
During description of results is required to give if the observed changes (decrease or increase) are statistically significant or not. It concerns especially changes at the level of 2-3%.
Materials and methods
Line 433 Thermosacc Dry® strain - producer, country?
Line 468 - Were the samples for sugar and glycerol analysis subjected to any preparation or not?
Line 482 Was the supernatant from wine samples subjected to any treatment before dosing onto the HPLC column?
Line 489 It is suggested to describe in more details the principle for determining trehalose using the anthrone method
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript has been enhanced and I propose its publication.
