ARS | Publication request: CHARACTERIZATION OF EXTRACELLULAR LYTIC ENZYMES PRODUCED BY THE POSTHARVEST BIOCONTROL AGENT CANDIDA OLEOPHILA

Submitted to: Abstract of International Horticultural Congress
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2003
Publication Date: June 21, 2003
Citation: BAR-SHIMON, M., YEHUDA, H., GOLDWAY, M., WISNIEWSKI, M.E., DROBY, S. CHARACTERIZATION OF EXTRACELLULAR LYTIC ENZYMES PRODUCED BY THE POSTHARVEST BIOCONTROL AGENT CANDIDA OLEOPHILA. ABSTRACT OF INTERNATIONAL HORTICULTURAL CONGRESS. 2003.

Technical Abstract: Enhancing the efficacy of biocontrol agents may be the most important need to assure their success as a viable alternative to the use of synthetic fungicides for the control of postharvest diseases of fruit. In our efforts to identify genetic traits of the yeast, Candida oleophila (the yeast used in the postharvest control product, Aspire), that may play an important role in biocontrol activity and determining their potential to enhance efficacy, we have been studying the ability of the yeast to produce fungal cell-wall-degrading-enzymes. Our study has focused on four enzymes secreted by the yeast: exoglucanase, endoglucanase, chitinase, and protease. The influence of the type of carbon source and rate of growth on the production of these enzymes by the yeast antagonist was determined by using calorimetric assays and plates containing specific substrates utilized by these enzymes. SDS-PAGE and activity gels of partially purified enzyme preparations were used to study isozyme profiles. In addition, a full-length gene (CoEXG1) of a secreted 1,3-B-glucanase was cloned from this yeast and analyzed. Sequencing analysis revealed that CoEXG1 carries the signature pattern of the five glycohydrolases family, has a putative secretion leader, and has a high degree of identity to other yeast 1,3-B-glucanases. C. olephila transformants harboring two copies of the CoEXG1 and its putative promoter region exhibited increased production (at least 2-fold) of B-1,3 glucanase. Cloning and sequence analysis of chitinase genes from C. oleophila is underway.