Production and application of bacterial cellulose for a filler of composite materials.

研究了以单晶状态的细菌纤维素（BC）作为复合材料的填料。BC膜经硬脂化后具有疏水性，并由环氧树脂组成。未添加填料的对照和含13%未改性BC膜并以2取代度改性的复合材料的抗拉强度之比分别为1.0、2.0和3.5（比重校正值）。采用接枝共聚法与甲基丙烯酸甲酯（MMA）等进行改性，并与环氧树脂等进行复合。MMA和环氧树脂接枝MFBC复合材料的抗拉强度比未改性MFBC提高50%。为了降低BC的生产成本，采用纤维素原料酶解得到的溶液作为培养基。与使用含有纯葡萄糖酶的标准HS培养基相比，BC的产生量增加了30 ~ 70%。结果表明，其原因是纤维素酶在热灭菌过程中失去了糖化活性。在HS培养基中加入改性纤维素酶后，BC的产率提高了近2倍。纤维素酶分为纯酶、内切酶、外切酶和β -氧化酶。修饰的-氧化酶对增加的贡献最大。这表明该修饰酶通过与葡萄糖形成络合物为葡萄糖键合提供了理想的条件。另一个原因是甘露糖和半乳糖以一定比例与葡萄糖共存。对产纤维素细菌醋酸杆菌的穿梭载体进行了分离。载体由醋酸杆菌质粒形成的PFF6（4.8kB）和由大肠杆菌质粒形成的PUC18（2.7kB）适合插入外源DNA片段，具有10^4/1ug以上的高转化效率。

It was studied to use bacterial cellulose (BC) in the state of single crystallite as a filler for a composite material. BC membrane was stearlated to be given hydrophobicity and composed with epoxy resin. The ratios of tensile strength of the control without the filler and the composite matirials contained 13% of unmodified BC membrane and modified it in the degree of substitution of 2 were 1.0, 2.0, and 3.5 in the value corrected by specific gravity, respectively. Also, BC membrane and BC fiber microfibrilized with a homogenizer (MFBC) were modified by graft copolymerization with methylmetacrylate (MMA) and etc. and composed with epoxy resin and etc. Tensile strength of composite material of MFBC graft polymerized with MMA and epoxy resin increased 50% compared with that used unmodified MFBC.To decrease production cost of BC, solution obtained by enzymatic saccharification of cellulosic materials was used as cultivation medium. In contrast to presuppose amount of producted BC increased 30 to 70% compared with that used standard HS medium with pure glucase. It was cleared that the reason was brougth from the cellulase lost saccharification activity during heat sterilization. Addition of the modified cellulase into the HS medium brougth an increasing of almost 2 times in the yield of BC. Cellulase was seperated pure enzyme, endo-, exo-, and beta oxydase. the modified beta oxydase was most contributed to the increasing. It suggested that the modified enzayme provided a desirable situation for bonding of glucoses by forming a complex with them. The another reason was on the coexistence of mannose and galactose in some ratio with glucose.Shuttle vectrs for cellulose-producing Bacterium Acetobacter were diviloed. The vectors formed PFF6(4.8kB) from plasmid of the acetobactor and it of PUC18(2.7kB) from it of a colon bacillus was fit for insertion of pieces of foreign DNA, and had a high transformation efficiency of the level over 10^4/1ug.