Picture from Cony Decok, Université Catholique de Louvain, Belgium

Pycnoporus puniceus

The genus Pycnoporus is a cosmopolitan group of basidiomycete fungi from the order Polyporales, the major group of wood decayers in temperate and tropical forests. The lignocellulose contained in the wood of standing trees and in dead wood contributes significantly to carbon storage on land. Because they are able to degrade the aromatic and saccharide polymers of wood, Pycnoporus fungi play a role in global carbon cycling.

White-rot filamentous fungi such as Pycnoporus species have a high potential for biotechnological processes, particularly for lignocellulosic feedstock biorefinery. The lignocellulose from plant biomass is a source of renewable carbon for the production of biofuels and chemicals, including high-value chemicals. Notably, complex raw materials from different origins (dedicated crops, agricultural and forestry wastes) and biorefinery wastes provide organic polymers and saccharides that can be converted to chemicals without impact on land usage for food/feed production or the preservation of natural areas.

Pycnoporus emerged in the early 1990s as an extraordinary resource to identify novel enzymes for efficient biomass degradation or transformation and became a genus of choice for biotechnological applications. Pycnoporus species were first highlighted for their original metabolic pathways involved in the conversion of plant cell wall aromatic compounds into high value molecules, e.g. aromas and antioxidants, and for their potential to produce a wide range of enzymes of industrial interest, such as glycoside hydrolases and lignin oxidases. Oxidases in particular are of great interest for the bioconversion of plant raw materials and plant wastes into valuable products, for biopulping and biobleaching of paper pulp, and for the biodegradation of organopollutants, xenobiotics and industrial contaminants. One long-known useful feature of the genus Pycnoporus is the ability to overproduce high redox potential laccases - multi-copper extracellular phenoloxidases - among other ligninolytic enzymes.

The genus Pycnoporus belongs to the Trametes phylogenetic clade, and is morphologically similar in all characters except for the conspicuous bright reddish-orange color of the basidiocarp. Pycnoporus puniceus (Fr.) Ryvarden, Norw. Jl Bot. 19: 236 (1972) [Basionyme; Trametes punicea Fr., Nova Acta R. Soc. Sci. ups, Ser. III, vol.1:98 1(1): 98, 1851] is close to P. sanguineus but differs by a thick fruit-body, larger and irregular pores (1-3 mm), and a cinnabar pileus becoming first brownish and finally blackish. First described from the Paleotropical area, Pycnoporus puniceus has since been found in the Neotropics. It develops mainly on dead logs in sun-exposed clearings. The extremophile features of P. puniceus and the several DNA insertions in ITS sequences make this species particularly interesting. The genome sequence of Pycnoporus puniceus allows the exploration of enzymes to be used as biocatalysts in plant biomass processing, among other applications. It will be used to deepen our understanding of the functional diversity within the genus, and of its enzymatic capabilities in relation to lignocellulose breakdown.