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A study of properties and enzymatic hydrolysis of bacterial cellulose

Kashcheyeva, Ekaterina I., Gladysheva, Evgenia K., Skiba, Ekaterina A., Budaeva, Vera V.
Cellulose 2019 v.26 no.4 pp. 2255-2265
Fourier transform infrared spectroscopy, X-ray diffraction, cellulose, crystal structure, culture media, drying, enzymatic hydrolysis, hydrolysates, oat hulls, reducing sugars, scanning electron microscopy, thermogravimetry
This study evaluates how bacterial cellulose (BC) properties influence the efficiency of enzymatic hydrolysis. BC was produced by the Medusomyces gisevii Sa-12 symbiotic culture in an enzymatic hydrolyzate obtained from oat hulls and was characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and X-ray diffraction. The enzymatic hydrolysis was examined with dried BCs unwashed and washed of culture medium components and cell debris, as well as with wet BC washed of culture medium components, at initial solid loadings of 10 and 30 g/L. The enzymatic hydrolysis of the BC sample unwashed of culture medium components and cell debris exhibited a substrate conversion degree of 56.3–66.6%. The conversion degree of the BC samples washed of culture medium components and cell debris was 89.4–99.5%. The removal of culture medium components and cell debris increased the conversion degree by 1.5 times. The drying of wet BC was found to decrease the enzymatic hydrolysis rate but it did not affect the conversion degree: the maximum yield of reducing sugars of 99.5% was achieved in 56 h for dried BC and in 16 h for wet BC. The substrate’s impurity content (growth medium components and cells) and moisture had the greatest effect on the performance of enzymatic hydrolysis of BC. The high BC crystallinity index of 90% was found to be not a determinant for the enzymatic hydrolysis efficiency.