Discovery of antimicrobial natural products made by Trichoderma spp. and study of their biosynthesis

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Papaya (Carica papaya L.) plantations around the world are being devastated by papaya dieback disease caused by Erwinia mallotivora infections and lead to plant death. Biocontrol measures are the most promising to explore as other strategies such as crop management, chemical treatment or the use of resistant plants are either not manageable or not available. Three strains from the genus Trichoderma have been identified as active against E. mallotivora. This project has for aim to purify and characterise secondary metabolites from those three Trichoderma strains showing bioactivity against E. mallotivora. To do so, the first step will be to purify all major metabolites made by all three strains using HPLC and testing their activity on Gram-negative bacteria, such as Escherichia coli and E. mallotivora. NMR spectroscopy experiments will then be performed on a few metabolites which show strong antimicrobial activity against E. mallotivora to characterise them and elucidate their structure. Once characterised, the genomes of the three strains will be explored to identify candidate BGCs responsible for their production. This will be facilitated as AntiSMASH detection of BGCs has already been performed. After identification of the BGCs, work with CRISPR/Cas9 deletions or heterologous expression coupled with LC/MS analysis and NMR spectroscopy experiments will be performed to elucidate the role of each gene present in the cluster.