Synthesis of Super-High-Viscosity Poly-γ-Glutamic Acid by pgdS-Deficient Strain of Bacillus licheniformis and Its Application in Microalgae Harvesting
, Xin Li 1,*, Dongbo Cai 2, Yangyang Zhan 2, Xin Ma 2 and Shouwen Chen 2,*Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsINTRODUCTION
The idea in lines 47-49 is not well connected with the rest of the documented.
In line 50, "remains lower". What does it mean?
With scientific names, the first time is written in its complete form (Bacillus subtilis). After that, it must always be written in its condensed form, even with other species of the same genera (B. subtilis, B. licehniformis). Please upgrade the format throughout the document
and re-write the last paragraph since it mixes two works.
The last paragraph of the introduction works as a prelude to the research; please only outline the objectives without explaining the results.
METHODS
Which algal strain was used?
from where was sourced the strain?
Which culture media was used?
please describe the culture conditions of algal production
RESULTS
Author Response
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Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsSynthesis of Super-high Viscosity Poly γ-Glutamic Acid by the 2 pgdS-Deficient Strain of Bacillus licheniformis and its Application in Microalgae Harvesting 1. Author must improve the Introduction section for better coherence? For instance, consider enhancing the flow by reorganizing some parts. Moving the discussion on γ- PGA’s characteristics and applications (such as biodegradability, water solubility, etc.) to the beginning would provide readers with valuable context before presenting the experimental procedures. 2. The author should use a consistent format for terms, such as molecular weight (Mw). Currently, the manuscript refers to molecular weight in both Mw and kDa. Standardizing terminology throughout will improve readability. 3. Authors must elaborate on the significance of the findings regarding pgdS gene knockout in Bacillus licheniformis WX-02 and its effect on γ-PGA production? Additionally, clarifying why gene deletion is preferred over post-synthesis modifications (such as environmental pH alterations or grafting) would enhance the study's practical relevance for industrial applications. 4. In the methodology section, the author should provide more detail on strain and plasmid selection. For example, include a sentence explaining why B. licheniformis WX-02 was chosen as the parental strain and clarify the specific function of plasmid T2(2)-Ori in enabling gene knockout. 5. The author should provide a more thorough explanation here of how kanamycin sensitivity was used to confirm these events. 6. Cite relevant literature to support the methodology and experimental design. 7. Mention if any control experiments were conducted to validate the results. 8. The study mentions that knocking out the pgdS gene led to oxygen insufficiency and nitrite accumulation. Providing more mechanistic insights into how this gene knockout affects these parameters would be beneficial. 9. Ensure that all units and measurements are clearly stated and consistent throughout the text.
Comments on the Quality of English Language10. Check the spelling and grammatical errors.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsIt is an interesting work whe the pgdS gene in Bacillus licheniformis WX-02 was knocked out using homologous recombination, and the batch fermentation performances of the recombinant strain WX-ΔpgdS were compared to those of WX-02.
In the introduction, little reference is made to the use of microalgae as a wastewater treatment technology. This topic should be discussed before entering into the harvesting strategy with low energy consumption.
There is also a lack of content on alternatives for using or adding value to algal biomass.
L. 95 to 99: dd the references from which information was taken for the production medium.
l. 215-221: Nitrate removal is referred to in the abstract and analysis of results as an achievement. However, nothing is said about nitrate in the introduction. In the methods there is not enough information to understand how the nitrate appeared and why it is important to analyze its removal. Rephrase and introduce this information in the introduction and methods.
l. 228-232: the same for nitrite…
Author Response
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Reviewer 4 Report
Comments and Suggestions for Authors1. Indicate the fermentation conditions for the production of PGA in the abstract.
2. The role/applications of PGA should be clearly discussed in the Introduction.
3. In Figure 2, please clearly mention in the graph which line is wild-type and which is recombinant strain.
4. Could the authors provide insights into the yield and cost-effectiveness of producing γ-PGA with the pgdS-deficient B. licheniformis strain in comparison to other strains or commonly used chemical flocculants in microalgae harvesting?
5. What operational and environmental benefits does γ-PGA offer over synthetic polymers in the context of microalgae harvesting? Are there any potential limitations or concerns regarding its biodegradability that the authors could address?
6. Can the authors comment on the reusability or stability of γ-PGA across various environmental factors (e.g., temperature, pH) that are relevant to industrial-scale microalgae harvesting?
Author Response
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Author Response File: Author Response.pdf
