ผลของออกซิเจนและสารอาหารในอาหารเลี้ยงเชื้อต่อการสร้างเซลลูโลส ของแบคทีเรีย / โดยอังคณา พันธ์ศรี = Effects of oxygen and medium compositions on bacterial cellulose synthesis / Angkana Phunsri
The objective of this research was to study the effect of dissolved oxygen on cellulose production in Acetobacter sp. TISTR975 in coconut water. It was found, that the optimum cellulose production was obtained at 2.5 cm height after 8 days of incubation in coconut medium containing 5.1% sucrose with pH 4.75 in the static culture. Although the initial dissolved oxygen has been reported to affect height, volume and surface area of cellulose producing during cultivation, the result revealed that even dissolved oxygen decrease to nearly zero level at 6 hour post cultivation, the production of cellulose still remained. The result also showed that cellulose production was depending proportionally on the surface area. Cellulose was accumulated at the surface of the medium where the film contacted directly with air. With shaking condition, the optimum cellulose production was obtained after incubation in coconut medium containing 4.98% sucrose with pH 4.9 and 100 rpm rotary shaking. The increase in dissolved oxygen by increasing shaking over 100 rpm, led to the decrease of cellulose production due to the conversion of glucose to gluconic acid during metabolism. When thickening agent of carboxymethyl cellulose (CMC), xanthan gum and carageenan were added to the medium, the cellulose products obtained had different appearance. Only CMC was found to increase cellulose production. The effect of concentration of CMC from 0.1 to 0.3% on cellulose production was studied. It was found that CMC at 0.2% increased cellulose production by 1.42 times to that of control within 3 days. Higher CMC concentration decreased the cellulose production due to the lowering in dissolved oxygen which effected on cells growth.