Analysis of secondary metabolite biosynthetic gene clusters in lichen metagenomes

Abstract

Lichens are organisms resul-ng from the symbio-c associa-on between a fungus and a photosynthe-c partner, a green alga or a cyanobacterium. The unique chemical diversity that results from this way of life reveals numerous compounds with various therapeu-c interests. To exploit this poten-al, I use a recent method of genome reconstruc-on for six species of Pel-gera lichens and highlight the capabili-es of automated bioinforma-cs tools in the context of this metagenomic study. ASer obtaining the genome assemblies, the gene-c mo-fs involved in the biosynthesis of secondary metabolites of cyanobionts were inves-gated with automated bioinforma-cs tools. In a first step, this study demonstrated the validity of the metagenomic assembly protocol to reconstruct the genome of cyanobionts of the genus Nostoc from Pel-gera species collected in the wild. In a second step, the inves-ga-on of the Nostoc genomes revealed a remarkably high biosynthe-c poten-al and promise for the discovery of new natural products. The gene clusters mainly detected were associated with the NRPS (non-ribosomal pep-de synthetases) and PKS (polyke-de synthases) enzyme synthesis pathways. On the other hand, the majority of the gene-c biosynthe-c pathways detected in this study had no biological descrip-on to date. These observa-ons highlighted the interest in automated methods in the search for new metabolomic profiles. Finally, the iden-fica-on of par-cularly rich secondary metabolite synthesis poten-als revealed by cyanobionts from P.appalacchensis, P.asia-ca, P.borenquensis, and P.mikado species, suggested a gene-c heritage.