The Effect of pH, Metal Ions, and Insoluble Solids on the Production of Fumarate and Malate by Rhizopus delemar in the Presence of CaCO3
Round 1
Reviewer 1 Report
In this paper, the effects of different conditions on the production of fumaric acid and malic acid by Rhizopus delemar in the presence of CaCO3 were studied. There are many research contents in this paper, and some interesting phenomena were also found. This study provides a relatively simple method for the sustainable production of malic acid from R. delemar.
- In the experiment of this paper, it is more reasonable to measure by the amount of substance than by weight, especially when comparing CaCO3 with MgCO3 and calculating the relationship between the output of FA and Ma and the use of CaCO3.
- Many discussions and conclusions in this paper are the same as those in reference 28, and the differences need to be explained particularly.
- There are a lot of mistakes in references, such as the missing of the name of this article, for example: ref. 7, 14, 15, 17, 18, 27, 28.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript intitled: “The effect of pH, metal ions, and insoluble solids on the production of fumarate and malate by Rhizopus delemar in the presence of CaCO3” describes the effect of CaCO3 in the production of fumarate and malate by Rhizopus delemar, investigating the reasons for that. They also produced fumarate followed by in situ hydration of fumarate to malate.
The manuscript is well written, very clear and experiments are performed with careful considerations. Several results support their conclusions. This study can be of reference for future studies.
Small corrections are needed:
Do not initiate sentences with numbers: ex page 4, line 134; page 19, line 568; page 20, line 586; page 21, line 640
Table 1: Specify ICP and PS
Page 19, line 536 : degree symbol is missing in “40 C”
Line: 551: (SI2mL each)???
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript is well presented and written, I only have some minor comments to improve it:
Figure 2a does not have error bars, please add them
Page 6 lines 190-191. Ethanol has a pKa of 16, therefore it exists at a protonated species at pH below 14. Thus, the statement made is false (Ethanol’s hydroxyl group is known to 190 cause the pH to be slightly basic), please erase this.
Page 7 lines 219-220. pH will be higher when adding MgCO3 simply because you are adding 20% more carbonate (as moles) when adding 100 g/L of MgCO3 instead of 100 g/L of CaCO3, please state this in the manuscript.
Figure 3, add error bars to all data
Page 9, line 291. Separate 3.9mm as 3.9 mm
Page 12, line 356. Separate 100h as 100 h
Page 14, line 396. Separate 80h as 80 h
Figure 7, add error bars to all data
Page 16, line 430. Separate 477h as 477 h
Page 17, lines 488 and 498. Separate 72h as 72 h
Page 18, line 505. Separate 101h as 101 h
Page 18, line 508. Separate 112h as 112 h
Page 18, lines 522-523. “a slight increase in pH occurred due to increased ethanol concentrations in the fermentation broth”. It is inferred that ethanol per se is increasing pH, which is not true. Rewrite this please.
Page 19, line 536 and 538. Change “120 hours” to 120 h, and “18 hours” to 18 h
Page 19, line 540. Use L for liters in “8 × 106 ml -1” (8 × 106 mL -1)
Page 19, line 548 and 552. Change “1 hour” to 1 h, and ”24 hours” to 24 h
Page 19, line 551. This is not clear: “SI2mL”
Page 19, line 553. Change “for a different fermentations” to “for different fermentations”
Replace hours for h throughout the remainder text
Page 19, line 574. Separate 2mm as 2 mm
Page 20, line 586. Separate 10M as 10 M
Page 20, line 593. Write minutes as min
Page 20, line 595. Fix: immpbilised
Page 20, line 606-607. Separate 36h and 200h as 36 h and 200 h
Page 20, line 614. Separate 477h as 477 h
Page 20, line 616. Change “The slow variations in pH was intended” to “The slow variation in pH was intended” or “The slow variations in pH were intended”
Page 20, line 619. Separate 72h as 72 h
Page 21, line 635. Separate 1M as 1 M
Page 21, line 642. “infections” as in contaminations?
Page 21, line 648. Delete the extra parenthesis in “(0.3 mL L-1 H2)SO4)”
Please add a table that establishes MA and FA production (in g/L) reported by others using R. delemar, compare it to the productions of both in this work (highest concentration)
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I have no other question.
