For what it is worth, I posted a link to the stream in another thread dealing with "Plumes of Methane". The reason for not starting a new thread is that earlier I posted a link to Mumma's DPS40 talk that is working that relates to a recent paper being published regarding Martian local concentrations of methane. During the lecture Mumma noted that the regions where the methane was observed seemed to relate to places seen by MRO that indicate possible subsurface movement. This could indicate that the methane is coming from the subsurface. Atreya has written a few papers on subsurface abiotic production of methane and has also speculated on how this can occur at somewhat shallower depths prior to Mumma's discovery.

Biotic methane is neither ruled in nor ruled out as yet according to what Mumma said in the DPS lecture. So methane may still remain as a possible biomarker. McKay and Porco recently wrote a paper regarding the purity of methane as compared to other present hydrocarbons suggesting that a composition that is more than 99.9 percent pure methane is a further biomarker. Perhaps since Mumma's DPS presentation, measurements have been made of other hydrocarbons that might indicate that this "softer" biomarker has been teased out of the data or whether the concentrations favor the abiotic interpretation.