Studies on sphere-like bacterial cellulose produced by Acetobacter xylinum under agitated culture

Certain strains of the cellulose producing bacteria Acetobacter xylinum have been shown to produce cellulose in the form of isolated sphere like particles. This novel form of cellulose may have applications in many fields ranging from food products to biomedical materials. In this work, we studied sphere-like cellulose formation as a function of agitated culture rotational speeds and flask size. Results clearly showed that cellulose spheres formed with a rotational speed above 100 rpm from JCM 9730 strain. Sphere sizes ranging from 0.5 mm to 10 mm diameter were observed at rotational speeds of 200 rpm (250 ml flask) and 150 rpm (150 ml flask), respectively. Scanning electron microscopy analysis of lyophilized cellulose spheres indicated that culture rotation speed had an impact on the internal structure of the sphere. Larger sphere-like particles produced at 125 RPM exhibited a layered structure whereas the central region did not exhibit a layered structure and was solid and relatively homogenous. Smaller sphere-like particles produced at 150 RPM were hollow but also exhibited a layered structure in the outer shell.