Screening of Trichoderma strains by optimized conditions in test plate media for siderophore production and measuring of cellulytic enzyme

The production of siderophore and cellulase by Trichoderma species is one of the effective indexs in plant growth, effective control and management of pathogens as well as application in industry. Therefore, primary screening of best isolates is very important based on the defined indicators.

In this study, the optimal conditions for the qualitative and quantitative production of siderophore and cellulase were investigated using test plate method for the initial screening of 27 Trichoderma strains. For measuring cellulase enzymes (Endoglucanase, exoglucanase and beta glucosidase), the reactive dyes phenol red, congo red (0.5, 0.05 and 0.015%) were used at pH levels of 4, 5, 7 and 9 with carbon sources including Avicel, CMC and cellobiose. Quantitative measurement of cellulase was investigated using the dinitrosalicylic acid method. Screening of Trichoderma strains for siderophore production was studied by CAS agar method as mycelial culture and crude extract in a well method.

The results of this research showed phenol red 0.015% under pH5 is the best reagent for detection of cellulase, Because of there is no inhibition on mycelial growth and the purple zone diameter is clear. In quantitative cellulase assay, the highest enzyme specific activity is related to T. harzianum CT-763 with 3 U/mg. T. atroviride CT-482, CT-473 and CT-865 were known as active strains in siderophore production, which were able to produce two types of siderophore, hydroximate and catechol. The results of siderophore production in liquid medium using the well method showed that T. afroharzianum CT-891 has the highest siderophore production by creating a halo zone of 1.2 cm, while T. harzianum CT566 produced the lowest amount of siderophore without creating halo.

Considering the application efficiency using of siderophore and cellulase in sustainable agriculture and importance of the role of Trichoderma species in production these metabolites, the well method for siderophore and dinitrosalicylic acid method for cellulase detection suggested. In this study T. atroviride and T. harzianum species had the highest production in siderophore and cellulase, respectively