Investigating the Feasibility of Applying Xanthan, Dextran, and Rhizobia Exopolysaccharides for paper reinforcement

Document Type : Original Article


1 Department of Conservation, Faculty of Archaeology, Cairo University

2 the grand Egyptian museum

3 National research Center


A new process using microbial exopolysaccharides (EPSs) was developed recently for paper consolidation. This procedure is completely unique in that, besides inhibiting fungal growth, it also improves the mechanical properties of paper. In the present article, the potential of enhancing the mechanical properties of the treated papers is investigated. three microbial exopolysaccharides (xanthan, dextran, and rhizobia exopolysaccharides) were produced by continuous culture The maximum production of xanthan and dextran were obtained by adding a fresh medium in bioreactor at 182 ml/h (0.091 h-1 dilution rate) and 288 ml/h (0.144 h-1 dilution rate), respectively, while the maximum concentration of Rhizobial exopolysaccharides was recorded at 136 ml/h (0.069 h-1 dilution rate). Continuous cultivation of X. campestris, R. legumin Sarum and L. mesenteroides increased the xanthan, Rhizobial exopolysaccharides and dextran production 23.6, 46.5 and 16.2%, respectively, compared with bioreactor as a batch culture. Tests were undertaken to evaluate improvements in mechanical properties induced by these microbial biopolymers on two types of papers and compared with eight commercial polymers used broadly in paper consolidation. It was found that the exopolysaccharides of xanthan tested acted as reinforcement agents when introduced in the paper, significantly increasing the mechanical properties in comparison with the commercially available polymers used in paper conservation. The effect was significant in different papers tested, demonstrating the protection and strengthening of brittle paper. In addition, a 1.5% concentration of Xanthan functioned as a mold inhibitors; no visible fungal growth was recorded for 90 days in low humidity on Whatman paper treated with Xanthan.


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