Bioconversion of elephant grass (Pennisetum purpureum) acid hydrolysate to bacterial cellulose by Gluconacetobacter xylinus.

AIMS: To evaluate the possibility of elephant grass acid hydrolysate converting into bacterial cellulose (BC) produced by Gluconacetobacter xylinus CH001 and to characterize the morphology and structure of the cellulose produced. METHODS AND RESULTS: Acid-hydrolysed and detoxified elephant grass acid hydrolysate was inoculated with G. xylinus CH001. After 14 days of static fermentation, about 6·4 g l(-1) of BC could be generated. Meanwhile, 60·4% (w/w) of BC yield on sugar consumption was obtained. Scanning electron micrographs illustrated that the network of cellulose fibres became denser, and the diameter changed with the growth. FT-IR spectra showed almost same results for all the BC samples collected on different culture time. X-ray diffractograms demonstrated that the crystalline form of BC was cellulose I, the crystallinity increased to 53·58%, and the crystallinity index reached up to 99%. CONCLUSIONS: Elephant grass acid hydrolysate could be utilized efficiently for BC production by G. xylinus CH001. Structure analysis on the cellulose produced showed its potential of being excellent material for further application. SIGNIFICANCE AND IMPACT OF THE STUDY: Our studies for the first time examined the bioconversion of low-cost elephant grass into high-value BC and the changes in its morphology and structure following the culture time.