Review for 10.1186/s12876-020-01195-1 (2020)

Reviewer ’s report  
 
Title: Intestinal fl ora imbalance affects bile acid metabolism a nd is associated with gallstone 
formation.  
 
Version: 1 Date: 05 Dec 2019  
 
Reviewer: Prashant Nighot  
 
Reviewer's report:  
 In the manuscript titled, 'Intestinal microbes affect bile acid metabolism involved in gallstone 
formation,' Qiang Wang and co -authors studied and analyzed the fecal microbiota composition in 
gallstone patients. The authors show that compared to controls, the diversity of fecal microbiota 
is reduced and the abundance of Firmicutes is also decreased. Furthermore, the 7a -
dehydroxylating gut bacteria were significantly increased while cholesterol -lowering bacteria 
were reduced in gallstone patients.  
* The auth ors mentioned that there was an increase in free bile acids and secondary bile 
acids in the enterohepatic circulation. In methods or results section, I could not find what kind of 
samples were tested and how the samples were processed in these experiments.  
* One potential limitation of this study is that the fecal microbial composition may not 
reflect small intestinal microbiota. This point may be included in the discussion section.  
* The authors concluded that "gut microbiota dysbiosis affects gallstone fo rmation through 
changes in bile acids and cholesterol metabolism." (page 11, line 8 -10) Though the study shows 
convincing changes in the fecal microbiota in the gallstone patients, the study is correlative at 
best. The causal role of  
        dysbiosis and altered bile acid and cholesterol metabolism is not established. I suggest the 
conclusion and the title should be modified accordingly.  
* I suggest that the authors should include Institutional human subject study number in the 
manuscript.  
* Please correc t the sentence on page 3 line 60 - page 4 line 1.  
* The subheading on page 6 line 52 can be improved (mention the groups instead of '2 
groups').  
* Labeling the individual panels in the fig. 6 A and B (with phylum, class, order, family, 
and genus) will make  it easier for the readers.  
* Mention Fig 7 E in the results text (page 8, line 19 -20). 
* Please correct the figure 7 legend, panel K.  
* The manuscript needs language editing at several places.  
 
Are the methods appropriate and well described?  
If not, please specify what is re quired in your comments to the authors.  
 
No 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, plea se explain in your comments to the authors.  
 
No 
 
Are you able to assess any statistics in the manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further  
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, f ees, funding, or salary from an 
organisation that may in any way gain or lose financially from the publicat ion of this 
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation t hat may in any way gain or lose 
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or are you current ly applying for any patents  relating to the content of the 
manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any ot her financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have  no competing interests' 
below. If your reply is yes to any, please giv e details below.  
 
I declare that I have no competing interests.  
 
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