Transcriptome Analysis Revealed the Molecular Mechanism of Acetic Acid Increasing Monascus Pigment Production in Monascus ruber CICC41233

Round 1

Reviewer 1 Report

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Author Response

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Reviewer 2 Report

This study addressed the effect of the addition of acetic acid to standard rice flour medium on the growth of filamentous fungus Monascus ruber and production of industrially important Monascus pigments (MPs). The authors find that acetic acid enhances both growth and MP production. This is in contrast to the addition of HCl at the same pH. Transcriptomic analysis of differentially expressed genes between the control group, the acetic acid group, and the HCl group at 2 days and 6 days growth revealed mainly differences in primary metabolism, leading to the conclusion that the addition of acetic acid as a carbon source enhanced the production of the precursors of MP biosynthesis, acetyl-CoA and malonyl-CoA, as well as energy stores in the form of ATP, NADH and NADPH. However, growth in the presence of acetic acid also increased the expression of genes implicated in the direct production of MPs. The conclusions are supported by the data and provide a framework for enhanced large-scale production of MPs.

One minor comment: It would be helpful to provide the final concentration of acetic acid used in the media. 

Author Response

Comments 1. One minor comment: It would be helpful to provide the final concentration of acetic acid used in the media.

Response 1. Thank you for your careful review. We have marked the concentration of acetic acid in detail in the manuscript. 2 mL acetic acid (34.94 mM) was added to1 L rice flour fermentation medium.