Department of Agricultural and Biological Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
J Biol Eng. 2009 Jul 24;3:12. doi: 10.1186/1754-1611-3-12.
Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS) were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC) production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L) that was 2.5-fold greater than the control (2.82 g/L). The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93%) and similar crystal size (5.2 nm) to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher Tmax compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC. The results clearly demonstrated that implementation of PCS within agitated fermentation enhanced BC production and improved its mechanical properties and thermal stability.
细菌纤维素已被应用于食品工业，例如用于制作低卡路里的甜点、沙拉和加工食品。它也被应用于造纸行业，以提高纸张强度；应用于电子行业，用于制造音响扬声器的声膜；应用于制药行业，作为过滤膜；以及应用于医疗领域，作为伤口敷料和人造皮肤材料。在这项研究中，为了提高木醋酸杆菌生产细菌纤维素的产量，分别在发酵培养基中实施了不同类型的塑料复合支撑体（PCS）。根据细菌纤维素的产量，选择了最佳的营养化合物组成的 PCS。选择的 PCS 被应用于生物反应器中，以考察其在分批发酵中的对细菌纤维素生产的影响。使用 X 射线衍射（XRD）、场发射扫描电子显微镜（FESEM）、热重分析（TGA）和动态机械分析（DMA）对所生产的细菌纤维素进行了分析。在 13 种 PCS 中，由于其高氮含量、适中的氮浸出率和足够的生物质附着在 PCS 上，选择了 SFYR+型 PCS 作为木醋酸杆菌生产细菌纤维素的固体支撑体，用于分批生物膜反应器。PCS 生物膜反应器的细菌纤维素产量（7.05 g/L）是对照（2.82 g/L）的 2.5 倍。XRD 结果表明，PCS 生长的细菌纤维素表现出更高的结晶度（93%）和相似的晶体尺寸（5.2nm），与对照相同。FESEM 结果表明，木醋酸杆菌附着在 PCS 上，生成了交织的细菌纤维素产物。TGA 结果表明，PCS 生长的细菌纤维素保留了约 95%的水分能力，低于悬浮细胞反应器中生产的细菌纤维素。PCS 生长的细菌纤维素的 Tmax 也高于对照。最后，DMA 结果表明，与对照的细菌纤维素相比，PCS 生物膜反应器中生成的细菌纤维素增加了其机械性能值，即断裂应力和杨氏模量。结果清楚地表明，在搅拌发酵中实施 PCS 可以提高细菌纤维素的产量，并改善其机械性能和热稳定性。
