Zymomonas mobilis
Zymomonas mobilis is a rod-shaped, gram- negative bacterium. Usually the bacteria are immobile, in the movable stage, it has 1-4 polar flagella. The cells usually occur in pairs and are rod-shaped. Zymomonas mobilis is acid tolerant, it grows at pH values from 3.5 to 7.5.
Zymomonas mobilis is a facultative anaerobe and produced by fermentation energy. It grows, however, even in environments with low oxygen concentration, thus also microaerobically. Zymomonas mobilis is used for the alcoholic fermentation of the juice of the agave Agave americana. The resulting fermented drink is called pulque. Therefrom by distillation of "real" tequila is derived. Glucose of Agavensafts is not degraded in this fermentation as in the alcoholic fermentation by yeast via glycolysis, but via the Entner- Doudoroff pathway.
Fermentation runs 3 - to 4- times faster than with yeast and the ethanol yield is higher: 92 to 94 % over 88 to 90 % for yeast. However, the substrate of claims Zymomonas mobilis are higher than those of similar yeasts, will be only about 3 sugar degraded, molasses and the like can not be used as a substrate. The resulting biomass can be difficult or impossible to be fed.
System
Zymomonas mobilis is the only species of its genus, which belongs to the family Sphingomonadaceae. The other genera of the family are not facultative anaerobic, they can only grow with oxygen ( obligately aerobic ).
There are two subspecies:
- Zymomonas mobilis subsp. francensis
- Zymomonas mobilis subsp. mobilis
In some cases a third, Zymomonas mobilis is still subsp. pomaceae, calculated to do so.