Native Cellulose II Production by Acetobacter Xylinum Under Physical Constraints

Acetobacter xylinum, which normally produces ribbon-like microfibrils of cellulose I, occasionally synthesizes a band-like cellulose (native band, or NB) having a cellulose II crystal structure with a putative folded-chain structure. In contrast to a previous finding of NB production by a mutant strain of A. xylinum, we found that the wild-type strain also produced NB when incubated on agar plate medium. Incubation of the same strain in liquid media of varying viscosity with the addition of polyethylene glycol (PEG) resulted in the production of normal ribbon at low viscosities and NB at high viscosities. This behaviour was independent of the molecular weight of PEG and there seemed to be a critical level in viscosity for the switching from ribbon production to NB production. These findings strongly suggest that NB production is induced by a low mobility of cells in the culture medium due to physical constraints.