N~+离子束辐照诱变选育细菌纤维素高产菌株

为获得细菌纤维素(Bacterial cellulose,BC)高产菌株,同时改善BC材料学性能,采用低能N+离子束辐照技术对木醋杆菌(Acetobacter xylinum)进行了诱变选育。将菌落大小、光滑度、致密度、润湿度以及BC膜形成速率、柔韧度、BC产量等作为筛选依据,建立了平板-96孔板-试管筛选体系,筛选得到2株BC产量提高且产物材料学性能改良的目标菌株5D、2D。菌株5D BC产量为4.84 g/L,比出发菌株BC产量提高了89.06%,菌株2D BC产量为4.53 g/L,比出发菌株BC产量提高了76.95%。利用FT-IR、XRD、SEM、拉力试验等方法对目标菌株产物性能进行了研究,结果表明,目标菌株5D、2D发酵BC均具有高于出发菌株发酵BC的结晶度、抗拉强度及较小的断裂伸长率,具有更为致密的层状结构以及清晰的纤维束三维网状结构,表明其具有较为优良的力学性能。目标菌株的获得对BC产量的提高和性能改良奠定了基础。

Mutation Screening to Detect Strains that Produce Bacterial Cellulose at High Yield by N+ Ion Beam Irradiation

In order to obtain strains that produce a high yield of bacterial cellulose (BC) and improve the properties of BC, N+ ion beam irradiation was used to conduct mutation screening in Acetobacter xylinum. A plate-96-well plate-cuvette screening system was established, in which parameters such as the size, smoothness, density, wettability and rate of the colony formation, pliability, and yield of the BC film were chosen as the screening criteria. Two target strains, 5D and 2D, were obtained that could produce BC with improved product properties at an enhanced yield. The BC yields of 5D (4.84 g/L) and 2D (4.53 g/L) were 89.06% and 76.95% higher than that of the original strain, respectively. Fourier transform-infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and a tensile test were used to study the properties of BC. The results showed that the BC produced by the target strains had higher crystallinity and tensile strength, a smaller elongation at break, a denser layered structure, and a clearer three-dimensional network structure compared with the product from the original strain, indicating that they had superior mechanical properties. The success in obtaining the target strains lays a foundation for improving the BC yield and properties.