ACID-HYDROLYSIS BEHAVIOR OF MICROBIAL CELLULOSE-II

A mutant strain of Acetobacter xylinum produces cellulose of anomalous band-like form ('native band'), and this material has been found to b e cellulose II, presumably having a folded-chain structure (according to recent work by Kuga et al.). In addition to the previous results of electron diffraction, X-ray analysis showed that this band material w as composed of virtually pure cellulose II. We have studied the acid h ydrolysis behaviour of this material to obtain additional evidence for the proposed structure. When hydrolysed with 1 N hydrochloric acid at 100 degrees C, the degree of polymerization (DP) of the material decr eased rapidly from 322 (<(DPw)over bar>/<(DPn)over bar> = 3.83) to 18. 3 (<(DPn)over bar> = 1.19). The latter value (levelling-off DP) corres ponds to the observed width (10 nm) of strand-like constituents of the band material. The sample dissolved in and regenerated from 8.75% aqu eous sodium hydroxide lost its original characteristic morphology and became irregular-shaped agglomerates. The levelling-off DP of this reg enerated sample was 55.2 (<(DPw)over bar>/<(DPn)over bar> = 2.53), a t ypical value for common regenerated celluloses. These findings as a wh ole strongly suggest that the cellulose molecules in the native band a re selectively cleaved at sharply folded parts by acid, producing frag ments of the length of folding periodicity.