| 摘要: | 木質醋酸菌(Komagataeibacter xylinus, K.xylinus)具有好氧性，可將葡萄糖、果糖、乳糖轉化為醋酸，並產生細菌纖維素 (Bacterial cellulose, BC)。細菌纖維素為K. xylinus所生產的胞外多醣體，其具有高商業價值，包含高結晶性、高保水力、高生物相容性、奈米級網狀結構等特性。在其他文獻中，以饋料批次發酵 (fed-batch)進行K. xylinus培養，其生物反應器為單一開口，因此僅能從上方饋料而造成細菌纖維素分層，因此本研究以市售之茶壺作為培養裝置，藉由側管抵達細菌纖維素下方進行饋料。
本研究先以HS培養基 (Hestrin and Schramm medium, 1954) 在20 g/L、10 g/L葡萄糖進行K. xylinus培養，再將研究分為兩種策略: 其一，以初始10 g/L葡萄糖作為基質進行批次發酵，使葡萄糖快速降低，其產量為1.18 g/L；進行饋料批次發酵，在培養第4天、第6天分別饋入3 g/L、8 g/L葡萄糖，其最終產量為2.83 g/L，與批次發酵相比產量增加了139.83 %，且細菌纖維素仍保持完整無分層。將細菌纖維素進行材料分析: FTIR其官能基並無改變且無新的官能基出現；TGA發現細菌纖維素可達360-376℃之熱穩定性；XRD分析細菌纖維素計算出結晶度可達87-89%；DSC分析細菌纖維素之熔點介於173-187℃；以FE-SEM觀察細菌纖維素呈現圓柱、棒桿狀。
其二，以初始20 g/L葡萄糖進行批次發酵，其產量為3.92 g/L；在第4天、第7天饋入7 g/L、3 g/L葡萄糖，所得到之產量為5.97 g/L，與批次發酵相比，產量增加34.62 %。將細菌纖維素進行材料分析: FTIR其官能基並無改變且無新的官能基出現；TGA發現細菌纖維素可達368-378℃之熱穩定性；XRD分析細菌纖維素計算出結晶度可達87-91%；DSC分析細菌纖維素之熔點介於179-185℃；以FE-SEM觀察細菌纖維素呈現圓柱、棒桿狀。
Komagataeibacter xylinus is aerobic, can convert glucose, fructose, and lactose into acetic acid and produce bacterial cellulose. Bacterial cellulose is an extracellular polysaccharide produced by K. xylinus. It has high commercial value, including high crystallinity, high water retention, high biocompatibility, nanoscale network structure equipment is and other characteristics. In other papers, K. xylinus culture with fed-batch fermentation, its bioreactor is a single opening. Therefore, it can only be fed from above, causing bacterial cellulose to stratify. This study uses commercially available teapots as bioreactor.
In this study, HS medium was used to culture K. xylinus at 20 g/L and 10 g/L glucose. Then divide the research into two strategies: first, batch fermentation with the initial 10 g/L glucose as the substrate, that glucose is quickly consumed, and its output is 1.18 g/L; carry out fed-batch fermentation, feed 3 g/L and 8 g/L glucose on the 4th and 6th day of culture respectively, the final output is 2.83 g/L, which is an increase of 139.83% compared with batch fermentation, and the bacterial cellulose remains intact without delamination. Material analysis of bacterial cellulose: FTIR has no changes in its functional groups and no new functional groups appear; TGA found that bacterial cellulose can reach a thermal stability of 360-376°C; XRD analysis of bacterial cellulose calculates that the crystallinity is go to 87-89%; DSC analysis of the melting point of bacterial cellulose is between 173-187℃; FE-SEM observation of bacterial cellulose is cylindrical and rod-shaped.
Second, the initial 20 g/L glucose was used for batch fermentation, and the yield was 3.92 g/L; on the 4th and 7th day, 7 g/L and 3 g/L glucose were fed in, and the yield was 5.97 g/L, compared with batch fermentation, the yield increased by 34.62%. Material analysis of bacterial cellulose: FTIR has no changes in its functional groups and no new functional groups appear; TGA found that bacterial cellulose can reach a thermal stability of 368-378℃; XRD analysis of bacterial cellulose calculates that the crystallinity is go to 87-91%; DSC analysis of the melting point of bacterial cellulose is between 179-185°C; FE-SEM observation of bacterial cellulose is cylindrical and rod-shaped. |
