Co-Overexpression of RIB1 and RIB6 Increases Riboflavin Production in the Yeast Candida famata
, Oleksii Lyzak 2, Justyna Ruchala 3, Kostyantyn Dmytruk 1 and Andriy Sibirny 1,3,*Round 1
Reviewer 1 Report
The subject of the manuscript is of interest and in the scope of the journal. The aim of the Authors is to construct riboflavin overproducer strain based on the flavinogenic yeast C. famata. However, the study has some flaws and in my opinion, a revision is needed before to be considered for publication in the journal.
Introduction should be improved:
Line 51: “however, each has its own advantages and disadvantages”
Please mention the most important advantages and disadvantages of production of riboflavin using these two microorganisms.
Line 63: use italic to C. famata and please check whole manuscript, there are many such errors.
Line 76: it was already written in line 60.
Material and methods section:
Line 157: please add the conditions – rpm, temp of the shake cultivation.
Discussion - the results are poor discussed. The discussion section have only five references. Please indicate other references with similar results or references from which you can obtain information to help you to discuss your results.
Author Response
Dear Ms. Kelsey Chen Thank you for your mail and comments to our mansucript ID fermentation-1641716 entitled "Co-overexpression of RIB1 and RIB6 increases riboflavin production in the yeast Candida famata". We are grateful to both reviewers for manuscript review and critical comments which we found very useful and agree with all of them. We edited our manuscript correspondingly taking into account each comment of both reviewers. Edited or added text is highlighted in red. Fragment of the text with high similarity (section Introducrion) has been rewritten.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors aimed at improving the production of riboflavin by the yeast Candida famata.
The authors have constructed seven expression cassettes for the overexpression of RIB1, RIB6 and RIB7 containing one, two of three genes in different combinations. Those cassettes were introduced into different strains the wild-type and two overproducers.Overexpression did not affect biomass production while riboflavin production was increased up to 653 mg/L and 403 mg/g of CDW showing an improvement of 13% of riboflavin and a 23% in riboflavin yield. The presented results demonstrate that that the coexpression of RIB1 and RIB6 is an important strategy to improve riboflavin production in yeast.
Minor comments
L120 during editing the restriction sites indicated as underlined in all primers is not shown.
L114 The I for the restriction enzymes do not need to be in italic. For gene expression, it is not indicated which promoter are used for the overexpression. Please clarify this point. Strain names and RIB gene overexpression are indicated as follow: for example, L2/RIB1/RIB6 I would prefer L2/RIB1-RIB6 witch will more clear that in first the strain L2 / then the overexpression plasmid containing the cassette containing the two genes RIB1-RIB6.
L230 Obtained results encourage us to express the combination of RIB1 and RIB6.
The Figure 4 is small and I suggest to have line 1 AD, line 2 BE, line 3 CF with fist the growth on left and riboflavin on right. The figure will be therefore bigger.
Author Response
Dear Ms. Kelsey Chen Thank you for your mail and comments to our mansucript ID fermentation-1641716 entitled "Co-overexpression of RIB1 and RIB6 increases riboflavin production in the yeast Candida famata". We are grateful to both reviewers for manuscript review and critical comments which we found very useful and agree with all of them. We edited our manuscript correspondingly taking into account each comment of both reviewers. Edited or added text is highlighted in red. Fragment of the text with high similarity (section Introducrion) has been rewritten.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors answered properly to all the questions and modified the manuscript accordingly, improving its quality.
Author Response
Thank you for the opinions of the reviewers and their comments.
