Enhancing Bioactive Cordycepin Production via Precision Fermentation with an Engineered Aspergillus oryzae
and Sukanya Jeennor *
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this study, the authors explored the condition of producing bioactive cordycepin by controlling the fermentation using engineered Aspergillus oryzae. The result is interesting. But I suggest to modify the manuscript before accept.
1. There are some formatting errors in the MS, and the author should carefully check and make revisions, such as excessive spaces.
2. In lines 38-39, the authors shoed that the cordycepin production can reach 8.6–14.3 g/L in the mutant C. militaris strain. While, in this study, the concentration is 1.7g/L. Some discussion should be given to show the results is competitive.
3. Have the microorganisms used in the experiment been preserved? If so, please provide the deposit number.
4. For figure 2b-c, this response surface seems irregular, which means that the fermentation conditions chosen by the author are not suitable. The author should provide an explanation for this.
5. The word “submerged fermentation (SmF)” only appears once, the abbreviation can be deleted.
6. In section 2.7, all instruments should indicate detailed information, including HLPC.
7. In lines 60-70, the authors should highlight the innovation about the research.
8. What is the basis for the author's selection of these research conditions? In fact, there are many factors that affect microbial growth.
9. Further discussion is needed on the mechanism of changing fermentation conditions to increase product concentration.
Author Response
Comments and Suggestions for Authors
In this study, the authors explored the condition of producing bioactive cordycepin by controlling the fermentation using engineered Aspergillus oryzae. The result is interesting. But I suggest to modify the manuscript before accept.
- Thank you for your kind suggestions and comments. According to the queries raised by the reviewer. I would like to give answers and more information point by point.
- There are some formatting errors in the MS, and the author should carefully check and make revisions, such as excessive spaces.
Response 1. Thank you for pointing this out, some letters and excessive spaces in manuscript were carefully checked and revised.
- In lines 38-39, the authors showed that the cordycepin production can reach 8.6–14.3 g/L in the mutant militaris strain. While, in this study, the concentration is 1.7g/L. Some discussion should be given to show the results is competitive.
Response 2. According to your suggestion, more discussion on the optional of cordycepin production by A. oryzae compared with the C. militaris strain was added (P. 8, lines 279-283).
- Have the microorganisms used in the experiment been preserved? If so, please provide the deposit number.
Response 3. The deposit number of the engineered A. oryzae strain in culture collection (TBRC-BMGC 438) was added (P. 2, line 81)
- For figure 2b-c, this response surface seems irregular, which means that the fermentation conditions chosen by the author are not suitable. The author should provide an explanation for this.
Response 4. Adenine is an important precursor that is directly linked to cordycepin production in A. oryzae. However, for short-production period, over supplementation of adenine in culture (2.0 g/L) resulting the high residual adenine that might interfere product quality (P. 6, lines 210-213). As this limitation, the adenine concentrations of 0.5–1.5 g/L were used for DOE analysis. Therefore, the skewed response plot of adenine concentrations on cordycepin production might be observed (Figure 2B and 2C). To address this issue, the sentence was added on P. 7 (lines 248-251).
- The word “submerged fermentation (SmF)” only appears once, the abbreviation can be deleted.
Response 5. Thanks for your kind suggestion. As there were five SmF words in the manuscript (P2, lines 69 and 88; P8, lines 276 and 286; P9, line 289). I would like to maintain this abbreviation.
- In section 2.7, all instruments should indicate detailed information, including HLPC.
Response 6. The information of HPLC instrument was added in section 2.7 (P. 5 line 172)
- In lines 60-70, the authors should highlight the innovation about the research.
Response 7. According to your kind suggestion. The highlight of BBD and RSM analysis for medium optimization was added (P2, lines 69-74)
- What is the basis for the author's selection of these research conditions? In fact, there are many factors that affect microbial growth.
Response 8. Thank you for the good question. Yes, there are many factor affecting cell growth. For DOE analysis in this study, the factor was selected based on previous studies (Jeennor et al., 2023). They studied the effect of carbon sources (C5-C6 sugar), nitrogen sources (organic and inorganics, data not shown) and precursors (adenine, adenosine, glycine and glutamic) for cordycepin production and found that glucose, yeast extract and adenine are major factors for growth and cordycepin production of A. oryzae. However, their interactive concentrations on biomass and cordycepin production have not been understood. As such, DOE analysis was performed in this study to investigate the optimal glucose, yeast extract, and adenine concentrations for high cordycepin productivity by the engineered A. oryzae strain (P2, lines 64-69).
Jeennor, S.; Anantayanon, J.; Panchanawaporn, S.; Chutrakul, C.; Vongsangnak, W.; Laoteng, K. Efficient de Novo Production of Bioactive Cordycepin by Aspergillus oryzae Using a Food-Grade Expression Platform. Microb Cell Fact 2023, 22, 253.
- Further discussion is needed on the mechanism of changing fermentation conditions to increase product concentration.
Response 9. Additional discussion on fermentation strategies enhancing the product concentration was added in the section 3.3 (P. 8-9, Lines 283-288)
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript represents an investigation of the ooptimization of the cultivation condition of A. oryzae strain for cordycepin production and evaluation of the compound`s stability. The paper is well structured and informative. The topic is interesting and up to date.
I recoment a different type of presentation of figure 3. It is not clear what the letters a,b,c, represent and there is no information in the caption.
Author Response
The manuscript represents an investigation of the optimization of the cultivation condition of A. oryzae strain for cordycepin production and evaluation of the compound`s stability. The paper is well structured and informative. The topic is interesting and up to date.
- Thank you for your kind suggestions and comments. According to the queries raised by the reviewer. I would like to give answers and more information point by point.
I recoment a different type of presentation of figure 3. It is not clear what the letters a,b,c, represent and there is no information in the caption.
Response1 . Additional information of a,b,c letters in Figure 3 was given in figure legend (P. 10, lines 328-330).
Author Response File: Author Response.docx
