Isolation, Identificat ion and Biological Characteristics of A Strain of Purpureocillium lilacinum

Objective The study was conducted to investigate the growth, protease and chitinase activities of a strain of Purpureocillium lilacinum isolated from the stroma of Aschersonia aleyrodis on citrus under different culture conditions, with a view to providing a theoretical basis for the use of P. lilacinum as a biocontrol agent.

Method The strains of the stroma of A. aleyrodis from Hongjiang orange leaves were isolated and purified by tissue isolation, identified by a combination of morphological characteristics and molecular methods, and their protease and chitinase activities were determined by the Folin-phenol and DNS method.

Result The strain ZJPL1812 was identified as P. lilacinum by morphological observation and ITS sequence analysis. The best culture temperature for the strain was 30℃, and the suitable pH value was 5.0-9.0. The best mycelial growth was achieved when ammonium dihydrogen phosphate and maltose were used as the nitrogen and carbon sources; the highest protease activity was produced when peptone and sucrose were used as the nitrogen and carbon sources; and the highest chitinase activity was achieved when ammonium nitrate and soluble starch were used as the nitrogen and carbon sources.

Conclusion The strain can use many different kinds of nitrogen and carbon sources, with a wide range of acid-base adaptability and strong environmental adaptability. And it produces high protease and chitinase activities, indicating that it has some potential in biological control.