β-1,4-glucosaminoglucan (GG) was prepared from the sheath of a sulfur-oxidizing bacterium Thiothrix nivea. Recently, GG was found to be adsorbed by cellulose (paper) and is therefore potentially applicable as an aminating agent for cellulose. We attempted to increase the yield of GG using a fed-batch cultivation method. Furthermore, the behavior of GG molecules in water was theoretically and experimentally investigated. NMR analysis in combination with molecular dynamics calculation suggested that GG molecules tend to form soluble aggregates in water. It was experimentally revealed that the self-aggregation is enhanced by the addition of NaCl and reduced temperature. Adsorption of GG onto cellulose via hydrogen bonding was confirmed by molecular dynamics simulation. Adsorption was also promoted in the presence of NaCl but was inhibited by a reduction in temperature. Only 11% of the amino groups in the GG-treated paper was reactive, suggesting that GG molecules adsorbed by the paper were forming aggregates.
Keywords: Thiothrix nivea; Glucosaminoglucan; adsorption; aggregation; cellulose.