Biogas, a mixture of mainly methane and carbon dioxide,
is produced during the anaerobic digestion of biomass
by a complex microbial network. Due to its high
methane yield per hectare, maize is the most widely
used energy crop in Germany for biogas production [1].
Usually, whole plants are harvested, chopped and
ensiled for conservation. Ensilage also serves as a pretreatment
measure for enhanced biogas production.
The production of maize silage is a complex biochemical
process, where bacteria produce a number of organic
acids and alcohols from the maize plant material
which is rich in carbohydrates, mainly starch, cellulose
and hemicellulose. Several chemical and microbial silage
additives are used to control the ensilage process and prevent
undesirable kinds of silage fermentation. To stimulate
the ensilage process, homofermentative and/or heterofermentative
consortia or single strains of lactic acid bacteria
are used. The homofermentative bacterial metabolism