微生物原果胶酶高产菌株的筛选及发酵特性的研究

从24种不同来源的样品中筛选得到一株编号为XZ3的原果胶酶高产菌株，其酶活达126．4U／ml。通过对菌落形态及孢子囊形态的观察，初步鉴定是曲霉属菌株。在不同发酵时间内测定发酵液中还原糖、pH、湿菌体重、PPase及PGase活性。结果表明：该菌株发酵过程中，发酵液中的还原糖含量在菌体生长初期升高很快，在对数生长期又迅速下降；发酵液的pH保持恒定：菌体产酶与菌体生长几乎同步且PPase与PGase活性的变化规律一致，比值在一定范围内保持恒定。

Study on Strains Screening for Producing Protopectinase and Its Fermentation Properties

A strain XZ3, of high protopectinase activity, was screened out from 24 samples originated differently. Its enzymaticactivity arrived at about 126.4U/ml. The strain was identified as Aspergillus sp. by surveying the colony and sporangiumconformations. Studies on the pH, the content of reducing sugar, the weight of wet mycelium and the PPase and PGase activityof the fermentation system , determined in different time, showed that in the course of fermentation, the volume of reducing sugarincreased quickly in the early stage while decreased quickly when the mycelium was in logarithmic growth stage. The pH keptstable in the fermentation. The change of enzymatic activity was synchronous with the growth of mycelium and the ratio ofPPase and PGase activity kept constant to a certain extent.