该文以厌氧瓶和发酵罐研究了嗜热纤维梭状芽孢杆菌(Clostridium thermocellum)在厌氧条件下产纤维素酶的发酵条件,发现在厌氧发酵瓶中,在培养温度55 ℃、初始培养基pH 7、发酵60 h为最佳产酶条件,此时测得酶活为5.12 U/mL。在放大到5 L发酵罐上的厌氧分批发酵条件下的生长曲线、糖耗、补料时间和添加碳源的研究结果发现,培养到16 h后,菌体进入指数生长期,糖耗最大,并确定最佳补料时间为16～48 h,纤维二糖为最佳补料碳源,酶活最高达16.56 U/mL,显著高于发酵瓶。研究结果为利用嗜热纤维梭菌进行工业化发酵生产耐高温纤维素酶提供了依据。
Cellulase is widely used in food industries, but most of the cellulase currently used are not resistant to high temperatures. Clostridium thermocellum is a thermophilic anaerobic bacterium that produces cellulosome with high cellulase activity and hyperthermophilic property. The fermentation conditions of the cellulase production by the bacteria were studied in anaerobic bottles and fermenters. During the anaerobic flask fermentation, the optimum conditions for enzyme production were 55 ℃, pH 7, and 60 h of fermentation . The enzyme activity reached 5.12 U/mL under the above conditions. The growth curve and sugar consumption of the bacteria were studied in 5 L fermenter. Under batch fermentation, the feeding time and addition of carbon source were studied. The results indicated the growth of C. thermocellum turned in to the exponential growth phase after 16 h. Furthermore, optimal feeding time for carbon source was determinated at 16-48 h. Different carbon sources were studied under fed-batch fermentation conditions, cellobiose supplementation led to a significant increase in enzyme activity and reached to 16.56 U/mL, which was significantly higher than that of flask fermentation. The results provide the theoretical basis for industrial production of hyperthermophilic cellulase by C. thermocellum.
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