Effective enhancement of ramie anaerobic continuous flow degumming by chitosan and its microbiological mechanism

Based on a novel bio-degumming system, the effect of chitosan on the degumming effect of ramie was investigated. The degumming effect indexes before and after the addition of chitosan were assessed, and the enzyme activities (pectinase, xylanase, ligninase and cellulase) were detected. Meanwhile changes in microbial community structure were evaluated. Furthermore, the electron-donating effect of chitosan and cellulose was further simulated by Fukui function. Degumming effect indexes showed the addition of chitosan could effectively increase the breaking strength of degummed ramie (from 6.04 to 6.59 cN/dtex), reduce the fineness (from 10.06 to 8.039 dtex), so that more gums were removed (the residual gum ratio reduced from 16.55 % to 12.09 %) and more cellulose was retained in the degummed ramie (cellulose content increased from 78.01 % to 80.96 %). Enzyme activity measurements revealed that the addition of chitosan increased the activity of degumming enzymes (pectinase, xylanase and ligninase), while decreased cellulase activity. The addition of chitosan induced changes of the community structure, with an increase of degumming microorganisms and a decrease of cellulose-degrading microorganisms. According to Fukui function, chitosan has a stronger electron donating ability than cellulose, which might be one important reason for the changes in enzyme activities and community structures.