The food waste used as a substrate in our study has
inherent microflora that began the fermentation process
before feedstock sampling and freezing (suggested for the
presence of VFA in the feedstock characterization). In this sense, indigenous microflora as Megasphaera can be issued
into the reactor by feeding. Among others, the Megasphaera
genus is a typical beer spoilage bacteria, and despite their
anaerobic nature, some of these bacteria can survive in
aerosols [34]. Moreover, Megasphaera is commonly reported in
hydrogen-producing systems fed with food wastes, such as
cheese whey [35], waste bread [36] and cafeteria waste, even
after heat-treated inoculum is used [8], which suggests the
presence of this genus in food waste.