text: Levan is synthesized in archaea, fungi, bacteria, and a limited number of plant species. Fructans such as levan are synthesized from sucrose, a disaccharide containing glucose and fructose. In plants, the vacuole is where fructan production occurs. Sucrose:sucrose/fructan 6-fructosyltransferase is the fructosyltransferase in the vacuole which creates the beta 2,6 linkages to form the linear form of levan. Bacteria also use a fructosyltransferase known as levansucrase to form levan. These enzymes in bacteria form the 2,1 linkages in the linear basal chains of levan to allow for branching points to occur. Many bacteria produce levan in the cell exterior. This production can be sensitive to temperature, oxygen concentration, pH, and other factors. Levan production in bacteria is typically a sign of growth in population. There are also possible ways to produce by fracturing soybean mucilage.
  Levans are produced by microbes during colonization of a food substrate. Erwinia amylovora exudes levan and amylovoran as part of its biofilm. Together they contribute to its pathogenicity. In 2016, Ua-Arak et al.  developed a sourdough method with high levan output (among other exopolysaccharides).