Optimizing the HS medium for the production of microbial cellulose nanofibers using Acetobacter xylinum

Bacterial cellulose synthesized by some microorganisms, including Acetobacter xylinum, has been widely used in various industries due to its specific properties. The purpose of this study was to optimize the cultivation condition for the production of microbial cellulose in a new culture medium.   Materials & In this experimental study, new sources of carbon and nitrogen were added to the Hestrin-Schramm medium, containing A. xylinum, and incubated for 7 days under static conditions. Carbon sources included glucose, galactose, fructose, lactose, sucrose, maltose, ethanol, methanol, inositol, glycerol, xylose, and mannitol and nitrogen sources included ammonium sulfate, ammonium nitrate, sodium nitrate (1, 3, 6, 9  g/l HS medium), peptone and yeast extract (5, 10, 15, 20  g/l  HS medium). Sodium alginate and sodium acetate were used to investigate the viscosity effect and to adjust the medium pH. Scanning electron microscopy, X-ray diffraction, and FTIR spectroscopy technique were used in order to confirm the cellulose production. Sodium alginate and sodium acetate were used to investigate the viscosity effect and determine the pH adjustment. Scanning electron microscope, X-ray diffraction and FTIR spectroscopy technique were used in order to confirm the cellulose production.   Four carbon sources including glycerol (without a significant drop in pH), glucose, fructose, and inositol produced the highest amount of cellulose, respectively. Organic nitrogen sources, particularly peptone, had a great impact on cellulose production, unlike mineral nitrogen sources. The optimum amount of sodium alginate as the viscosity agent and sodium acetate as the buffer was 1.2 and 3 gram per liter of culture medium, respectively. X-ray diffraction showed the highest crystallinity index in medium containing glucose, fructose, inositol, and glycerol, respectively. The amount and intensity of infrared absorption in FTIR scanning of the products of culture media containing glucose and glycerol and comparing them with other similar cellulose graphs confirmed the cellulose production. Furthermore, Scanning Electron Microscopy studies clearly showed a nanofiber structure of microbial cellulose in media with better carbon sources.   According to our findings, glycerol and peptone have the most impact on microbial cellulose production. It was also indicated that addition of 2.1 g/ L sodium alginate to the culture medium as the viscosity agent along with pH control during the process by adding 3 g/ L sodium acetate can have a significant effect on cellulose production.