Plastics have become ubiquitous in both their adoption as materials and as environmental contaminants.Widespread pollution of these versatile, man-made, and largely petroleum-derived polymers has resulted from their long-term mass production, inappropriate disposal, and inadequate end of life management. Polyethylene (PE) is at the forefront of this problem, accounting for one third of plastic demand in Europe in part due to its extensive use in packaging (European Parliament, 2020). Current recycling and incineration processes do not represent sustainable solutions to tackle plastic waste, especially once it becomes littered, and the development of new waste-management and remediation technologies are needed. Mycoremediation (fungal-based biodegradation) of PE has been the topic of several studies over the last two decades. The utility of these studies is limited by an inconclusive definition of biodegradation and a lack of knowledge regarding the biological systems responsible. This review highlights relevant features of fungi as potential bioremediation agents, before discussing the evidence for fungal biodegradation of both high-and low-density PE. An up-to-date perspective on mycoremediation as a future solution to PE waste is provided.

Phthalate esters (PEs, Phthalates) are environmentally ubiquitous as a result of their extensive use as plasticizers and additives in diverse consumer products. Considerable concern relates to their reported xenoestrogenicity and consequently, microbial-based attenuation of environmental PE concentrations is of interest to combat harmful downstream effects. Fungal PE catabolism has received less attention than that by bacteria, and particularly fungi dwelling within aquatic environments remain largely overlooked in this respect. We have compared the biocatalytic and biosorptive removal rates of din -butyl phthalate (DBP) and diethyl phthalate (DEP), chosen to represent two environmentally prominent PEs of differing structure and hydrophobicity, by marine-, freshwater-, and terrestrial-derived fungal strains. Bisphenol A, both an extensively used plastic additive and prominent environmental xenoestrogen, was included as a reference compound due to its well-documented fungal degradation. Partial pathways of DBP metabolization by the ecophysiologically diverse asco-and basidiomycete strains tested were proposed with the help of UPLC-QTOF-MS analysis. Species specific biochemical reaction steps contributing to DBP metabolism were also observed. The involved reactions include initial cytochrome P450-dependent monohydroxylations of DBP with subsequent further oxidation of related metabolites, de-esterification via either hydrolytic cleavage or cytochrome P450-dependent oxidative O-dealkylation, transesterification, and demethylation steps-finally yielding phthalic acid as a central intermediate in all pathways. Due to the involvement of ecophysiologically and phylogenetically diverse filamentous and yeast-like fungi native to marine, freshwater, and terrestrial habitats the results of this study outline an environmentally ubiquitous pathway for the biocatalytic breakdown of plastic additives. Beyond previous research into fungal PE metabolism which emphasizes hydrolytic de-esterification as the primary catabolic step, a prominent role of cytochrome P450 monooxygenase-catalyzed reactions is established.

Serpula wood-decay fungi occupy a diverse range of natural and man-made ecological niches. Serpula himantioides is a forest-floor generalist with global coverage and strong antagonistic ability, while closely related species Serpula lacrymans contains specialist sister strains with widely differing ecologies. Serpula lacrymans var. shastensis is a forest-floor specialist in terms of resource preference and geographic coverage, while Serpula lacrymans var. lacrymans has successfully invaded the built environment and occupies a building-timber niche. To increase understanding of the cellular machinery required for niche adaptation, a detailed study of the P450 complement of these three strains was undertaken. Cytochrome P450 monooxygenases are present in all fungi and typically seen in high numbers in wood decay species, with putative roles in breakdown of plant extractives and lignocellulose metabolism. Investigating the genomes of these related yet ecologically diverse fungi revealed a high level of concordance in P450 complement, but with key differences in P450 family representation and expression during growth on wood, suggesting P450 proteins may play a role in niche adaptation. Gene expansion of certain key P450 families was noted, further supporting an important role for these proteins during wood decay. The generalist species S. himantioides was found to have the most P450 genes with the greatest family diversity and the highest number of P450 protein families expressed during wood decay.

Phthalate esters (PEs) are environmentally ubiquitous micropollutants that are used as plasticizers and additives in diverse consumer products. Considerable concern relates to their reported xenoestrogenicity and the microbial-based attenuation of environmental PE concentrations is of interest to combat harmful downstream effects. Fungal PE catabolism has received less attention than that by bacteria, and particularly marine fungal species remain largely overlooked in this respect. We have compared the biocatalytic and biosorptive removal rates of di-n-butyl phthalate (DBP) and diethyl phthalate (DEP), chosen as two environmentally prominent PE representatives (exhibiting differing structures and hydrophobicities), by marine- and freshwater fungal strains. Bisphenol A, both an extensively used plastic additive and prominent environmental xenoestrogen, was included as a reference compound due to its previously well-documented fungal degradation. Partial pathways for DBP metabolization by these ecophysiologically diverse ascomycetes were proposed with the help of UPLC-QTOF-MS analysis. Species-specific biochemical reaction steps contributing to DBP metabolism were also observed. The involved reactions include initial cytochrome P450-dependent monohydroxylations of DBP with subsequent further oxidation of related metabolites, de-esterification via either hydrolytic cleavage or cytochrome P450-dependent oxidative O-dealkylation, transesterification, and demethylation steps - finally yielding phthalic acid as a central intermediate in all pathways. Beyond previous research into fungal PE metabolism which emphasises hydrolytic de-esterification as the primary catabolic step, a prominent role of cytochrome P450 monooxygenase-catalysed reactions is established.