Dear Dr. Elul and Co-Workers,

thank you for submitting your responses to Biogeosciences. All four reviewers appreciate the study and considered the manuscript well written; however all reviewers raised concerns that justify major revision. I conclude from your responses that you will be able to sufficiently address the concerns raised. Major points are:

- Missing molecular information (e.g., PilA proteins and FASTA files). Please provide.

- Missing geochemical information. Please add this information to the main manuscript (not the supplementary). The majority of reviewers considered geochemical information crucial to interpret the data.

- Please remove speculations about the capability of Methanothrix conducting AOM, since this conclusion appears not to be justified by your data.

- The possibility of ANME's conducting AOM in the incubations should be discussed.

- Please add thermodynamic considerations as suggested by one of the reviewers.

After I received your revised manuscript, it will be send back to at least 2 experts for a second round of reviews.

Let me know in case you have any questions.
Tina Treude

Dear Michal and Orit,

both reviewers are satisfied with your revisions (and so am I) and suggest that the manuscript is ready for publication. I am therefore pleased to inform you that I accept your manuscript subject to very minor technical corrections (see below).

With kind regards
Tina Treude

Technical Corrections:
- L138 of main text and S.DB.7 (p10 of supplement): McrA (not mcrA)
- L354: italicize pilA (gene name)
- S.DB.7 on page 10 of supplement: OmcS and PilA (not omcS and pilA)
- "bona fide" is two words, please correct throughout the manuscript