关键词: 外切聚半乳糖醛酸酶, Neosartorya fischeri P1, 果胶, 毕赤酵母

Abstract:

Polygalacturonases has great application value in food and feed industry, so finding new polygalacturonase can not only supply related enzyme information, but also provide more choices for industrial applications. In the study, a thermophilic fungus Neosartorya fischeri P1 was isolated from an acid mine in Yunnan Province. A novel exo-polygalacturonase gene, Nf-pg, was cloned from its genome. The gene Nf-pg was transformed into Pichia pastoris GS115 for heterologous expression. The recombinant enzyme Nf-PG was purified and characterized. The results indicated that the purified Nf-PG was most active at pH 4.5 and 55℃, and showed high stability at pH 2.0~9.0 and good thermal stability. There was still 80% residual enzyme activity after 60 min heat treatment at 50℃. The optimal temperature of deglycosylated recombinant enzyme Nf-PG-D was 50℃. Compared to Nf-PG, enzyme Nf-PG-D showed a decreased thermal stability, but the properties of optimal pH and pH stability were similar to Nf-PG. Product analysis proved that Nf-PG was a strict exo-type polygalacturonase. The excellent properties made Nf-PG an ideal candidate for applying in food processing.

Key words: exo-polygalacturonase, Neosartorya fischeri P1, pectin, Pichia pastoris