Biosynthesis and Properties Control of Bacterial Cellulose

培养基中添加3.5%浓度的酵母提取物可提高细菌纤维素（BC）的产量，其浓度高达标准培养物（0.5%酵母提取物）的两倍。随着酵母浸膏浓度的增加，细胞生长明显增加。在2天的孵育过程中，培养基的pH值从最初的5.9下降到3.5-4.5，但孵育时间延长后，pH值逐渐升高。然而，作为碳源的葡萄糖在4天的孵育过程中被完全消耗，纤维素的产生在长达15天的孵育过程中缓慢进行。培养基中过量的酵母提取物似乎在纤维素生物合成的活化剂中起作用。由xylinum醋酸杆菌（actobacter xylinum）生产的细菌纤维素（NBC）具有很高的机械强度和生物降解性。通过掺入水溶性聚合物（WSP）如羧甲基纤维素（CMC）、甲基纤维素（MC）和聚乙二醇（PEG）来控制其性能。少量wsp加入标准Hestrin-Schramm培养基中。在孵育期间将WSPs纳入BC。纤维素复合材料（BCC）将成为一种互穿聚合物。与NBC对照相比，MC对照的BCC重量产率为1.5倍，CMC对照为1.8倍。采用C%、CMC为45%、MC为20%的元素分析法测定BCC中MC和CMC的含量。从x射线分析来看，（110）的衍射由于（110）的失向而明显出现。WSPs影响BC的择优取向。BCC的杨氏模量约为NBC （30-40GPa）的1-3倍。纤维素酶对BCC （CMC）的降解时间为6小时，而对BCC （MC）的降解时间仅为20-40%。在原生土中进行降解试验时，所有BCC样品在30°C和NBC下均有明显的降解。有可能控制BC的生物降解性。该方法将用于合成一种具有良好生物降解性和其他功能的新型生物降解菌。在不同的生物反应器模式下，考察了产NBC的最有效的培养方法，并在此基础上设计了转盘式生物反应器。少

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