Effects of reaction conditions on cellulose structures synthesized in vitro by bacterial cellulose synthases

Cellulose was synthesized by cellulose synthases extracted from the Komagataeibacter xylinus (formerly known as Gluconacetobacter xylinus). The effects of temperature and centrifugation of the reaction solution on the synthesis products were investigated. Cellulose with number-average degree of polymerization (DPn) roughly in the range 60-80 and cellulose II crystal structure was produced under all conditions. The amount of cellulose varied with temperature and centrifugation, and the centrifugation at 2000 x g also slightly reduced the DPn. Cellulose production was maximal around the temperature 35 degrees C and without centrifugation. At higher temperatures and during centrifugation at 2000 x g the proteins started to denature, causing differences also in the morphology of the cellulosic aggregates, as seen with electron microscopy. These observations serve as a basis for discussions about the factors affecting the structure formation and chain length of in vitro synthesized cellulose. (C) 2015 Elsevier Ltd. All rights reserved.