Phospholipase A activity and the biocontrol potential of Trichoderma harzianum and Trichoderma atroviride.

The aim of this work was to study the phospholipase A (PLA) enzyme activity of extracts from Trichoderma harzianum 1A and Trichoderma atroviride αCp8 culture media. Fermentation on submerged culture was performed and PLA activity of extracts was evaluated as a function of culture time. A turbidimetric method for continuous analysis of phospholipase activity was applied. By this, vesicles rather than soluble substrates are used resembling the in vivo environment. In Trichoderma's culture experiments, lecithin phospholipids as inductors promoted a PLA expression level of the same order to the corresponding strain control assay. T. harzianum developed the highest PLA activity and was considered as the most potent strain. Furthermore, the activity level was clearly greater when the culture medium included the plant pathogenic fungus Sclerotium rolfsii. The T. harzianum strain showed the highest PLA potential. Besides, both T. harzianum and T. atroviride, developed higher PLA activity at the first days of culture. In the present work, T. harzianum 1A and T. atroviride αCp8 at a lower level, showed an important PLA potential for S. rolfsii control. On the other side, a lower relative response was observed when both Trichoderma strains were assayed against other pathogens such as Macrophomina phaseolina and Rhizoctonia solani. The present work contributes to the scientific knowledge about PLA activity in Trichoderma and could be useful for technological purposes to prepare formulations for the biological control of S. rolfsii in agriculture. [ABSTRACT FROM AUTHOR]