Figure 2. Three-dimensional response surface plot and con- tour curve for tannase activity showing the effects of agitation rate and MgSO4•7H2O.
above 2% (w/v), this carbon source exhibits a strong catabolic repression of enzyme synthesis [13].
A. G. DE MELO ET AL.
Over cultivation time, the substrate availability de- creases while there is an increase in the hydrolysis prod- uct. This condition may be unfavorable if the enzyme production is regulated by the end-product. The tannase production by A. niger [13] and A. japonicus [19] are repressed by gallic acid, suggesting that the enzyme production in these strains are regulated in this manner. In contrast, Aspergillus sp. GM4 tannase production is induced by gallic acid in cultivation medium, which demonstrates that the presence of the product in the me- dium (at the tested concentrations) does not repress the production process. This response to gallic acid was also observed for tannase produced by Emericella nidulans [22] and Bacillus massiliensis [7]. Gallic acid has been used to induce tannase production and has also been linked to the regulation of this process.
The use of statistical methodology to optimize the culture conditions and to improve enzyme production has been a useful tool for biotechnology and has recently received more attention. Some important parameters should be considered for microorganism growth and se- cretion of biotechnological products of industrial interest. The RSM can be used to analyze the influence of differ- ent parameters on enzyme production, to determine the statistical significance level, and to examine the statisti- cal interactions among the factors involved in the process. The “one-at-a-time” approach showed that four factors (tannic acid, sodium nitrate, agitation rate and incubation period) have the most influence on tannase production in A. niger, and the use of the CCRD and RSM approaches increased the enzymatic production 2-fold (from 9.8 U/mL to 19.7 U/mL) [23]. However, the tannase produc- tion by Aspergillus sp. GM4 increased 2.66-fold using the RSM under optimized conditions in submerged fer- mentation. Tannase production in submerged fermenta- tion by Aspergillus sp. improves at high aeration rates [20], as observed in studies with A. niger and Aspergillus sp. GM4. The agitation rate shows an important effect on the supply of nutrients, especially oxygen, for filamen- tous fungi cultivation. Furthermore, good mixing, mass and heat transfer require a threshold level of agitation. However, high agitation rates can lead to high energy dissipation rates and to high shear stress, which may re- sult in fragmentation and cell and mycelial network damage [24]. Therefore, it is important to find the opti- mal agitation rate for enzyme production without induc- ing mycelium damage.
Others factors that are important to tannase production are the supplementation of the culture medium with an adequate concentration of carbon, nitrogen and mineral
รูปที่ 2 แปลงพื้นผิวตอบสนองสามมิติและเส้นคอนทัวร์สำหรับกิจกรรม tannase ที่แสดงผลของอาการกังวลต่ออัตราและ MgSO4•7H2O ข้างบน 2% (w/v), แหล่งคาร์บอนนี้จัดแสดงปราบปรามการ catabolic ที่แข็งแกร่งของเอนไซม์สังเคราะห์ [13] A. G. DE MELO ET AL ช่วงเวลาเพาะปลูก ที่พื้นผิวมีอยู่เดอ-creases ขณะนั่นเป็นการเพิ่มไฮโตรไลซ์ผลิต-uct เงื่อนไขนี้อาจร้ายผลิตเอนไซม์กำหนดในผลิตภัณฑ์สุดท้าย การผลิต tannase โดยอ.ไนเจอร์ [13] และ A. japonicus [19] มี repressed ด้วยกรด gallic แนะนำว่า การผลิตเอนไซม์ในสายพันธุ์เหล่านี้ถูกควบคุมในลักษณะนี้ ในทางตรงกันข้าม Aspergillus sp. GM4 tannase ผลิตเป็นเกิดจากกรด gallic ในเพาะปลูก ซึ่งแสดงให้เห็นว่า สถานะของผลิตภัณฑ์ฉัน-dium (ที่ความเข้มข้นที่ทดสอบ) ปราบปรามกระบวนการผลิต กรด gallic ตอบนี้ยังได้ถูกตรวจสอบสำหรับ tannase ที่ผลิต โดย Emericella nidulans [22] และคัด massiliensis [7] กรด gallic ถูกใช้เพื่อก่อให้เกิดการผลิต tannase และยังมีการเชื่อมโยงกับข้อบังคับของกระบวนการนี้ The use of statistical methodology to optimize the culture conditions and to improve enzyme production has been a useful tool for biotechnology and has recently received more attention. Some important parameters should be considered for microorganism growth and se- cretion of biotechnological products of industrial interest. The RSM can be used to analyze the influence of differ- ent parameters on enzyme production, to determine the statistical significance level, and to examine the statisti- cal interactions among the factors involved in the process. The “one-at-a-time” approach showed that four factors (tannic acid, sodium nitrate, agitation rate and incubation period) have the most influence on tannase production in A. niger, and the use of the CCRD and RSM approaches increased the enzymatic production 2-fold (from 9.8 U/mL to 19.7 U/mL) [23]. However, the tannase produc- tion by Aspergillus sp. GM4 increased 2.66-fold using the RSM under optimized conditions in submerged fer- mentation. Tannase production in submerged fermenta- tion by Aspergillus sp. improves at high aeration rates [20], as observed in studies with A. niger and Aspergillus sp. GM4. The agitation rate shows an important effect on the supply of nutrients, especially oxygen, for filamen- tous fungi cultivation. Furthermore, good mixing, mass and heat transfer require a threshold level of agitation. However, high agitation rates can lead to high energy dissipation rates and to high shear stress, which may re- sult in fragmentation and cell and mycelial network damage [24]. Therefore, it is important to find the opti- mal agitation rate for enzyme production without induc- ing mycelium damage. อื่น ๆ ปัจจัยที่มีความสำคัญในการผลิต tannase คือ แห้งเสริมกลางวัฒนธรรมกับความเข้มข้นที่เพียงพอของคาร์บอน ไนโตรเจน และแร่ธาตุ
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