Approved with the following edits included or clarified 
-	The Introduction does not seem to spell out that the challenge is distinguishing the fluorescence  of methanogens  from  plant or other material in rumen samples- isn’t that the biggest challenge to overcome ?  it just says it can see methanogens – this can be tightened up I think. 
-	The acknowledgements should include PGGRC if the work goes back into the SSIF contract period prior to August 2021  - if its later and in the RGP period only then  they are probably OK.   If you mention PGGRC then that might suffice – there is no web presence for the RGP -  people looking it up might not find it.