Determination of protease and chitinase activities from Paecilomyces variotii NV01 isolated from Dak Lak pepper soil

Abstract

The filamentous fungus Paecilomyces is currently being developed as a biocontrol agent against plant parasitic nematodes, which often cause black leaf disease in pepper and coffee trees. Nematode eggs and cuticles are the infection sites for biocontrol agents that penetrate those areas by the production of lytic enzymes. Paecilomyces variotii NV01 was isolated from pepper soil from the Dak Lak province. The purpose of this work is to study the activity of protease and chitinase in the strain Paecilomyces variotii NV01. The protease activity was determined to be 82.3 U/ml in a 0.65% casein substrate concentration after 84 hours of culture, which was 6 folds higher than with a basal medium (12.7 U/ml). Exo-chitinase activity was found to be 37.28 U/ml after 84 hours of culture in a chitin substrate concentration of 0.75%, which is 4 folds greater than the basal medium. It was found that adding Ca²⁺ to the medium drastically altered chitinase activity, increasing it by 10.5%. A 5 mM concentration of Ca²⁺ was found to affect chitinase activity but not protease activity. Furthermore, the percentage of Meloidogyne sp. nematodes killed by Paecilomyces variotii NV01 after 96 hours of culture was 50.4%. Further study should be carried out in order to use this fungal strain to control plant parasitic nematodes.