This gradual acidification promotes the development of acid-tolerant LAB species such as Lactobacillus brevis, Lactobacillus
plantarum and L. buchneri (Holzer et al., 2003), which convert water-soluble carbohydrates (WSCs) mainly into lactic acid.
This is the fermentation phase, which starts when the ensiled mass has become anaerobic. It usually lasts for several days or
weeks, during which different groups of facultative aerobic or anaerobic microorganisms naturally found in plants compete
for available nutrients. In well-processed silage, LAB dominate the fermentation, rapidly producing the low pH conditions
that help to preserve the silage. In the event of accidental soil incorporation, a long aerobic phase or slow acidification, the
microbial communities in the silage will be dominated by Clostridia, yeasts, molds and accidentally incorporated pathogenic
microorganisms such as Listeria sp.