白腐真菌木质素降解酶的反应器发酵

为了获得更高的白腐真菌木质素降解酶的产量和相应的控制策略,应用5L搅拌罐生物反应器对氮限制下(C/N=56/2.2)P.chrysosporium产木质素降解酶进行了放大研究.结果表明,在分批发酵试验中,锰过氧化物酶(MnP)和漆酶(Lac)分别在培养第6d和第7d达到峰值,其酶活随时间的变化规律与摇瓶试验基本相同;而采用氮限制液体培养基进行补料没有获得更高的酶活,因此,可以得出采用发酵液体培养基作为补料液不利于白腐真菌持续产酶.另外,在分批发酵和分批补料发酵过程中,均发现体系pH值变化与白腐真菌生长和次生代谢产酶具有较好的相关性,当白腐真菌进入次生代谢阶段开始产酶时,体系pH值开始下降,随着发酵后期酶活的降低,pH值下降的幅度也逐渐变小,当体系酶活接近为0.0U/L时,pH值基本不再变化.因此,在实际发酵过程中,可以依据体系pH的变化间接了解白腐真菌的生长和产酶情况,而分批补料策略还有待于进一步研究.

Production of Ligninolytic Enzymes in Bioreactor

Production of ligninolytic enzymes under nitrogen limited conditions(C/N=56/2.2) was studied in a 5-L stirred tank bioreactor with a working volume of 2 L for obtaining higher production of ligninolytic enzymes by white rot fungus Phanerochaete chrysosporium BKM-F-1767 and its control strategy.Results show that the manganese peroxidase(MnP) and laccase(Lac) reached peak at the sixth day and the seventh day,respectively,and the variation of them with time in a batch cultivation are similar to the results by agitated Erlenmeyer flasks;however higher enzyme activity was not achieved by applying a fed-batch strategy,in which nitrogen limited medium was fed to the reactor.In addition,variation of pH during cultivation was related to the growth of P.chrysosporium and enzymes production during both batch and fed-batch cultivation.The pH value of liquid medium began to decline when the enzyme activity occurred in the system,and the decline became more and more slow along with the decrease of enzyme activity at the end of fermentation.So,pH would be as a control parameter to find out the growth of P.chrysosporium and enzymes production during incubating P.chrysosporium.However,fed-batch strategy still need further study.