Production of Biomodified Bleached Kraft Pulp by Catalytic Conversion Using Penicillium verruculosum Enzymes: Composition, Properties, Structure, and Application

Round 1

Reviewer 1 Report

The enzyme hydrolysis was employed to produce biomodified bleached kraft pulp, which was used to fabricate cryogel. The authors revealed that the properties and structure changes of modified kraft pulp after enzymatic hydrolysis. The properties of the fabricated cryogels are similar with the that from commercial MCC. The topic was interesting. But the followed issues should pay more attention.

1. Line 32, “55...67%” should be changed to “55-67%”. They are also happened in the main text several times.

2. The enzyme hydrolysis of pulp was well known, so the novelty of this study should mainly lay on the cryogel preparation and properties. The title could be changed accordingly.

3. The cryogel properties from biomodified pulp should be present clearly, particular the improvement from the control, which could justify the necessary of this process.

Author Response

Dear reviewer,

We appreciate your attention to our work. We have attempted to follow up on all of your recommendations. We have checked the English language and style of the manuscript and have made revisions. The recommendations are in bold, our comments and answers – in italics.

1. Line 32, “55...67%” should be changed to “55-67%”. They are also happened in the main text several times.

Response 1: We have corrected the sentence, line 32. We have made corresponding corrections throughout the entire text.

2. The enzyme hydrolysis of pulp was well known, so the novelty of this study should mainly lay on the cryogel preparation and properties. The title could be changed accordingly.

Response 2: The issue of complex processing using all polysaccharides remains unresolved despite the background of studying the enzymatic hydrolysis of cellulosic materials. In this work, we attempted to focus on the remaining non-hydrolyzed components of bleached kraft pulp. In terms of bioeconomics development in the forest complex, biomodified with enzymes pulp after washing can serve as an analogue of MCC derived with the use of acid. Moreover, as stated in the discussion, there is an opportunity to control the properties of the resulting product, the performance of which exceeds some of the parameters of conventional MCC. We consider the production of cryogels as another direction of the use of bleached kraft pulp, which allows increasing the added value of the resulting product. Therefore, using this title we wanted to show the key component in the practical implementation of enzymatic hydrolysis of cellulosic materials – biomodified kraft pulp, its properties as an MCC analogue and its application on the example of producing new structures – cryogels.

3. The cryogel properties from biomodified pulp should be present clearly, particular the improvement from the control, which could justify the necessary of this process.

Response 3: Thank you for the important recommendation. We would like to mention that this work is the first to show the possibility of producing cryogels from bleached kraft pulp. On the other hand, the implementation of deep biocatalysis involves not only obtaining glucose-rich hydrolysates, but also pulp with significant changes in composition, structure, and properties. In the paper, we endeavored to answer the following question: Are these polysaccharide by-products suitable for the production of cryogels? Yes, it is possible. However, depending on the degree of bioconversion, we can obtain a product with better or inferior to cryogels made of initial pulp properties. The further strategy of biocatalysis of such materials should be based on obtaining the required properties and further applications in pharmaceutics and other industries.

Reviewer 2 Report

Title – Production of Biomodified Bleached Kraft Pulp by Catalytic Conversion Using Penicillium verruculosum Enzymes: Composition, Properties, Structure and Application

            The manuscript deals with modified kraft pulp produced by enzymes produced by P. verruculosum aiming to produce high-quality cryogels. The English language is good and the authors show interesting results with a very good discussion. Thus, the manuscript has the potential for publication in Catalysts. However, I think the authors must improve the manuscript to submit it to another journal. Below I did some comments (C), questions (Q), or suggestions (S) to improve the manuscript.

Comments:

1.  (S) – Introduction: Please, cite the current world production of cryogels.
2. (S) – Results, pg. 4, line 138: It should be “…BP2, and BP3 had a lower yield of 2.0.…”.
3. (S) – Results, pg. 4, line 142: It should be “…biomodified kraft pulp had a low density of 0.049-0.115.…”.
4. (C) – Materials and Methods, pg. 8, line 261: Please, add the Global Positioning System (GPS) location for the area of the Pulp and Paper Mill.
5. (S) – Materials and Methods, pg. 8, line 264: It should be “…(72 % H₂SO₄, 4 %, 1 h, 121°C) [52] and …”. Please, type as 121°C instead of 121 °C. Do it in all text.
6. (C) – Materials and Methods, pg. 8, line 264: Please, cite the initial activity (for FPase) for the used cocktail.
7. (S) – Materials and Methods, pg. 8, line 273: It should be “The research used enzyme complexes (B1-221-151 and F10)…”.
8. (S) – Materials and Methods, pg. 9, line 277: It should be “…(25%), endoglucanases 1, 2, and 3 (10%), and endoxylanase (2%), determined…”.
9. (C) – Materials and Methods, pg. 9, line 286: Please, cite the enzyme load used in the experiments.
10. (C) – Materials and Methods, pg. 8, line 288: Please, cite the model and supplier for the used centrifuge.
11. (C) – Materials and Methods, pg. 8, line 297: Please, cite the model and supplier for the used centrifuge.
12. If possible cite the Figures and Tables before showing them.
13. References:

Put the microorganism´s name in italic in reference [2].

Author Response

Dear reviewer,

We are very grateful for the work you have done with our paper. We tried to take into account all your recommendations. Please find responses to the comments and suggestions below. We hope that the manuscript’s revised version with corrections and additions meets the acceptable quality for publication in the journal. The recommendations are in bold, our comments and answers – in italics.

(S) – Introduction: Please, cite the current world production of cryogels.

Response 1: The worldwide production of cryogels with specified parameters is based on the intended functions of cryogels. Previous studies have shown that the use of polysaccharides to produce cryogels for medical purposes is an actively developing field within the framework of laboratory research [1-4]. We could not find any information on the industrial production volumes of such materials in open sources. In the manuscript we have outlined the main articles and reviews that describe the current status of production of cryogels for medical purposes using the most common methods.

(S) – Results, pg. 4, line 138: It should be “…BP2, and BP3 had a lower yield of 2.0.…”.

Response 2: We have corrected the sentence, line 138.

(S) – Results, pg. 4, line 142: It should be “…biomodified kraft pulp had a low density of 0.049-0.115.…”.  

Response 3: We have corrected the sentence, line 142.

(C) – Materials and Methods, pg. 8, line 261: Please, add the Global Positioning System (GPS) location for the area of the Pulp and Paper Mill.

Response 4: In the “Kraft pulp” section, we have added GPS coordinates for the Mill.

(S) – Materials and Methods, pg. 8, line 264: It should be “…(72 % H₂SO₄, 4 %, 1 h, 121°C) [52] and …”. Please, type as 121°C instead of 121 °C. Do it in all text.

Response 5: We have corrected the sentence, line 264. We have made corresponding corrections throughout the entire text.

(C) – Materials and Methods, pg. 8, line 264: Please, cite the initial activity (for FPase) for the used cocktail.

Response 6: In the “Enzymes” section, we have added information on the initial activity (FPase) for the used enzyme complexes.

(S) – Materials and Methods, pg. 8, line 273: It should be “The research used enzyme complexes (B1-221-151 and F10)…”.

Response 7: We have corrected the sentence, line 273.

(S) – Materials and Methods, pg. 9, line 277: It should be “…(25%), endoglucanases 1, 2, and 3 (10%), and endoxylanase (2%), determined…”.

Response 8: We have corrected the sentence, line 277. We have made corresponding corrections throughout the entire text.

(C) – Materials and Methods, pg. 9, line 286: Please, cite the enzyme load used in the experiments.

Response 9: In the “Enzymatic hydrolysis” section, we have added information on the dosage of enzyme complexes used in the experiment, line 286.

(C) – Materials and Methods, pg. 8, line 288: Please, cite the model and supplier for the used centrifuge.

Response 10: We have added the name and model of the centrifuge used in the experiment, line 288.

(C) – Materials and Methods, pg. 8, line 297: Please, cite the model and supplier for the used centrifuge.

Response 11: We have added the name and model of the centrifuge used in the experiment, line 297.

If possible cite the Figures and Tables before showing them.

Response 12: In our manuscript we are referring to figures and tables several times. In order to prevent confusion we decided to keep these references.

References: Put the microorganism´s name in italic in reference [2].

Response 13:  We have written in italics the name of the microorganism, reference [2].

References

• Budtova, T., Aguilera, D. A., Beluns, S., Berglund, L., Chartier, C., Espinosa, E., Buwalda, S. J. Biorefinery approach for aerogels. Polymers. 2020, 12, 2779.  https://doi.org/10.3390/polym12122779.
• Shiekh, P. A., Andrabi, S. M., Singh, A., Majumder, S., Kumar, A. Designing cryogels through cryostructuring of polymeric matrices for biomedical applications. European Polymer Journal, 2021, 144, 110234. https://doi.org/10.1016/j.eurpolymj.2020.110234
• Savina, I. N., Zoughaib, M., Yergeshov, A. A. Design and assessment of biodegradable macroporous cryogels as advanced tissue engineering and drug carrying materials. Gels, 2021, 7(3), 79. https://doi.org/10.3390/gels7030079
• Tyshkunova, I. V., Poshina, D. N., Skorik, Y. A. Cellulose Cryogels as Promising Materials for Biomedical Applications. International Journal of Molecular Sciences, 2022, 23(4), 2037. https://doi.org/10.3390/ijms23042037

We would like to thank you once again for the recommendations. They were very helpful in the improvement of our manuscript. We hope that the revised version is of acceptable quality for publication in the Catalysts.