Contribution of DHN melanin to survival and growth of Neoarthrinium moseri in extreme environments

Abstract

Epiphyte Neoarthrinium moseri is a sordariomycete found in tropical forests in Colombia and Brunei. Whole genome analysis revealed a high potential for secondary metabolite (SM) production and cultivation on different media resulted in the expression of different yet unknown SMs. Additionally, microbiological assessment using different types of stresses (salinity, pH, temperature) indicated tolerance of the fungus to extreme environments. Under certain laboratory conditions, N. moseri forms black and tear-shaped conidia. The fungus shares this feature with its close relative Pestalotiopsis fici. We were able to identify the Biosynthetic Gene Cluster (BGC) responsible for the expression of 1,8-dyhydroxynaphthalene (DHN) melanin in N. moseri by comparing genomic data of N. moseri and P. fici. Deletion of the according polyketide synthase (PKS) resulted in loss of black color and tear-like shape of the conidia. However, in both strains DHN melanin-deficiency is not lethal to the strain. In this work we investigated the contribution of DHN melanin to the tolerance of N. moseri to extreme environments. In addition to the already used test conditions for microbiological assessment (salinity, pH, temperature), we tested the wildtype and the DHN-melanin deficient strain for their susceptibility to among others oxidative and heavy metal stress.