Lignocellulolytic Capability of Endophytic Phyllosticta sp.

Abstract

The Dothideomycetes represent the largest fungal class of Ascomycota. It is an ubiquitous class of fungi whose members span a wide spectrum of lifestyles and host interactions. The endophytic fungus Phyllosticta is one members of the Dothideomycetes, causing disease in economic crops. Phyllosticta was screened for the degradation of lignocellulosic biomass of commercial relevance, such as rice straw, rice husk, sorghum, wheat straw, miscanthus, lavender flower, and lavender straw. The highest degrading strains were identified from an initial screen and further analyzed for the secretion of lignocellulosic enzymes during growth on the different biomasses. With Phyllosticta capitalensis (MFLUCC14-0233), maximum activity of arabinase (944.18 U/ml culture), cellulase (27.10 U/ml), xylanase (10.85 U/ml), pectinase (465.47 U/ml), and laccase (35.68 U/ml) activities could be detected in the secretome during growth on lavender flowers and lavender straw. Phyllosticta capitalensis is thus an interesting new strain for the production of lignocellulosic enzymes during growth on cheap agro-industrial biomass. Keywords:Agro-industrial residues; Biological pretreatment; Dothideomycetes; Lignocellulosic biomass; Lignocellulytic enzyme; Phyllosticta IntroductionThe Dothideomycetes represent the largest fungal class within the phylum Ascomycota. It is a ubiquitous class of fungi whose members span a wide spectrum of lifestyles and host interactions [1][2][3]. Members of the Dothideomycetes can cause disease in every major crop [4]. Approximately 1,300 genera and 19,000 species have been identified either as endophytes, plant pathogens, or as saprophytes degrading plant biomass, thus threatening agriculture and food security throughout the world [5][6][7][8]. In addition to their mode of life, the Dothideomycetes are known for producing secondary metabolites grouped into four main categories based on their biosynthetic origin: polyketides, non-ribosomal peptides, terpenoids and tryptophan derivatives [9]. These secondary metabolites can be both toxic and beneficial to plants and humankind in applications such as agrochemicals, antibiotics, immunosuppressant's, antiparasitics, antioxidants and anticancer agents [10]. New Dothideomycetes are still being discovered worldwide and a large number of these strains remained unexplored regarding their potential use in biotechnology [11][12].Endophytes provide a broad variety of bioactive secondary metabolites with unique structures and so this class of fungi could be used as potential "nanofactories" producing a range of "green" alternatives to currently employed chemicals [13]. Although the ecological significance of endophytes is not completely clear, it is known that these fungi can exploit dead leaves immediately after their senescence and before they fall from the tree [14], and so could be also exploited for the production of enzymes acting on plant biomass.A well-known representative of Dothideomycetes fungi in metabolite studies is Phyllosticta (with a Guignardia anamorph)...