Giant panda are carnivorous bears which feed almost exclusively on plant biomass (i.e. bamboo). The potential contribution of its gut microbiome to lignocellulose degradation has been mostly investigated with cultivation-independent approaches. Recently, we reported on the first lab-scale cultivation of giant panda gut microbiomes and described their actual fermentation capacity. Fermentation of bamboo leaf using green dung resulted in a neutral pH, the main products being ethanol, lactate and H2. Fermentation of bamboo pith using yellow dung resulted in an acidic pH, the main product being lactate. Here, we cultivated giant panda gut microbiomes to test 1) the impact of mixed dung as inoculum; 2) the fermentation capacity of solid lignocellulose as opposed to organics-rich biofluids in the dung; 3) the artificial shift of pH from neutral to acidic on bamboo leaf fermentation. Our results indicate that i) gut microbiomes fermentation of solid lignocellulose contributes up to a maximum of 1/3 even in the presence of organics-rich biofluids; ii) alcohols are an important product of bamboo leaf fermentation at neutral pH; iii) aside hemicellulose, gut microbiomes may degrade plant cell membranes to produce glycerol; iv) pH, rather than portion of bamboo, ultimately determines fermentation profiles and gut microbiome assemblage.