Biosynthesis and Properties Control of Bacterial Cellulose

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Bacterial cellulose (BC) productivity has been enhanced by the presence of 3.5% concentration of yeast extract in the medium as high as twice of the standard culture(0.5% yeast extract). Cell growth increased markedly with an increase in yeast extract concentration. pH of the medium decreased from the initial 5.9 to the range of 3.5-4.5 during 2 days incubation, however, after the prolonged incubation gradual increasing in pH was observed. Glucose as a carbon source was nevertheless consumed thoroughly during 4 days incubation, cellulose production proceeded slowly as long as 15 days incubation. An excess of yeast extract in the medium appear to play an role in the activator for cellulose biosynthesis. Bacterial cellulose (NBC) produced by Acetobacter xylinum (A.xylinum) has both great mechanical strength and biodegradability.The properties were controlled by the incorporation of water-soluble polymers (WSP) such as carboxymethyl cellulose (CMC), methyl cellulose (MC) and polyethylene … More glycol (PEG). Small amounts of the WSPs were added to the standerd Hestrin-Schramm medium.The WSPs were incorporated into BC during incubation. The cellulose composite (BCC) will be a kind of interpenetrating polymer.The BCC yield by weight were 1.5 times for MC and 1.8 times for CMC as compared with the weight of NBC control. The contents of MC and CMC in the BCC were checked by elemental analysis of C%, 45% for CMC and 20% for MC,respectively. From the X-ray analysis, the diffraction of (110) appeared sharply as a resuli of the disorientation of (110). The WSPs influence the preferential orientation of BC.Young's modulus of the BCC was about 1-3 times that of NBC (30-40GPa). BCC (CMC) was degraded completely by cellulase for 6 hr, while only 20-40% of BCC (MC) was degraded for 48hr. For degadation test in native soil, all BCC samples were degaded considerably at 30ﾟC for 4 weeks as well as NBC.There is some possibility to control a biodegadability of BC.The method of BCC production will be used to synthesize a new type of BC having both excellent biodegradability and other functions. The most effective incubation methods for NBC production were examined in various mode of bioreactor, and then on the basis of the results, the bioreactor with rotating-disk has been designed. Less