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Potential of Wood-Rotting Fungi to Attack Polystyrene Sulfonate and Its Depolymerisation by Gloeophyllum trabeum via Hydroquinone-Driven Fenton Chemistry.

Krueger MC, Hofmann U, Moeder M, Schlosser D - PLoS ONE (2015)

Bottom Line: Up to 80% reduction in Mn of PSS where observed when fungal cultures were additionally supplemented with 2,5-dimethoxy benzoquinone, the oxidized from of 2,5-DMHQ.In contrast, white-rot fungi were unable to cause substantial depolymerising effects despite the expression of lignin-modifying exo-enzymes.Our results indicate that brown-rot fungi might be suitable organisms for the biodegradation of recalcitrant synthetic polymeric pollutants.

View Article: PubMed Central - PubMed

Affiliation: Department Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.

ABSTRACT
Synthetic polymers often pose environmental hazards due to low biodegradation rates and resulting accumulation. In this study, a selection of wood-rotting fungi representing different lignocellulose decay types was screened for oxidative biodegradation of the polymer polystyrene sulfonate (PSS). Brown-rot basidiomycetes showed PSS depolymerisation of up to 50 % reduction in number-average molecular mass (Mn) within 20 days. In-depth investigations with the most efficient depolymeriser, a Gloeophyllum trabeum strain, pointed at extracellular hydroquinone-driven Fenton chemistry responsible for depolymerisation. Detection of hydroxyl radicals present in the culture supernatants showed good compliance with depolymerisation over the time course of PSS degradation. 2,5-Dimethoxy-1,4-hydroquinone (2,5-DMHQ), which was detected in supernatants of active cultures via liquid chromatography and mass spectrometry, was demonstrated to drive the Fenton processes in G. trabeum cultures. Up to 80% reduction in Mn of PSS where observed when fungal cultures were additionally supplemented with 2,5-dimethoxy benzoquinone, the oxidized from of 2,5-DMHQ. Furthermore, 2,5-DMHQ could initiate the Fenton's reagent-mediated PSS depolymerisation in cell-free systems. In contrast, white-rot fungi were unable to cause substantial depolymerising effects despite the expression of lignin-modifying exo-enzymes. Detailed investigations with laccase from Trametes versicolor revealed that only in presence of certain redox mediators limited PSS depolymerisation occurred. Our results indicate that brown-rot fungi might be suitable organisms for the biodegradation of recalcitrant synthetic polymeric pollutants.

No MeSH data available.


Related in: MedlinePlus

Hydroxyl radical generation by G. trabeum under varied culture conditions.Production of TBARS from 2-deoxyribose monitored at 530 nm was used as an indicator. Conditions shown: culture in regular Wetzstein medium (■); azide-inactivated (●); no iron (♦); quinone-supplemented (▲). Symbols represent means ± standard deviation for triplicate cultures; standard deviations smaller than symbol size are not shown.
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pone.0131773.g004: Hydroxyl radical generation by G. trabeum under varied culture conditions.Production of TBARS from 2-deoxyribose monitored at 530 nm was used as an indicator. Conditions shown: culture in regular Wetzstein medium (■); azide-inactivated (●); no iron (♦); quinone-supplemented (▲). Symbols represent means ± standard deviation for triplicate cultures; standard deviations smaller than symbol size are not shown.

Mentions: Production of TBARS was used as a proxy for the production of hydroxyl radicals under four different culture conditions (Fig 4). Sodium azide-inactivated cultures showed practically no absorbance from deoxyribose-derived TBARS. Likewise, cultures deprived of iron showed an only weakly increased absorbance during the whole time course of cultivation. In contrast, quinone-supplemented cultures showed a clearly stimulated TBARS production during the first four days of cultivation and dropped to the level of regular cultures afterwards. Regular fungal cultures (i.e. those active cultures containing iron and PSS, but no other supplements) produced only low levels of TBARS during the first days of cultivation, but increased TBARS generation to an intermediate level after approximately one week and maintained that level until the end of the experiment at 20 days.


Potential of Wood-Rotting Fungi to Attack Polystyrene Sulfonate and Its Depolymerisation by Gloeophyllum trabeum via Hydroquinone-Driven Fenton Chemistry.

Krueger MC, Hofmann U, Moeder M, Schlosser D - PLoS ONE (2015)

Hydroxyl radical generation by G. trabeum under varied culture conditions.Production of TBARS from 2-deoxyribose monitored at 530 nm was used as an indicator. Conditions shown: culture in regular Wetzstein medium (■); azide-inactivated (●); no iron (♦); quinone-supplemented (▲). Symbols represent means ± standard deviation for triplicate cultures; standard deviations smaller than symbol size are not shown.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493105&req=5

pone.0131773.g004: Hydroxyl radical generation by G. trabeum under varied culture conditions.Production of TBARS from 2-deoxyribose monitored at 530 nm was used as an indicator. Conditions shown: culture in regular Wetzstein medium (■); azide-inactivated (●); no iron (♦); quinone-supplemented (▲). Symbols represent means ± standard deviation for triplicate cultures; standard deviations smaller than symbol size are not shown.
Mentions: Production of TBARS was used as a proxy for the production of hydroxyl radicals under four different culture conditions (Fig 4). Sodium azide-inactivated cultures showed practically no absorbance from deoxyribose-derived TBARS. Likewise, cultures deprived of iron showed an only weakly increased absorbance during the whole time course of cultivation. In contrast, quinone-supplemented cultures showed a clearly stimulated TBARS production during the first four days of cultivation and dropped to the level of regular cultures afterwards. Regular fungal cultures (i.e. those active cultures containing iron and PSS, but no other supplements) produced only low levels of TBARS during the first days of cultivation, but increased TBARS generation to an intermediate level after approximately one week and maintained that level until the end of the experiment at 20 days.

Bottom Line: Up to 80% reduction in Mn of PSS where observed when fungal cultures were additionally supplemented with 2,5-dimethoxy benzoquinone, the oxidized from of 2,5-DMHQ.In contrast, white-rot fungi were unable to cause substantial depolymerising effects despite the expression of lignin-modifying exo-enzymes.Our results indicate that brown-rot fungi might be suitable organisms for the biodegradation of recalcitrant synthetic polymeric pollutants.

View Article: PubMed Central - PubMed

Affiliation: Department Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.

ABSTRACT
Synthetic polymers often pose environmental hazards due to low biodegradation rates and resulting accumulation. In this study, a selection of wood-rotting fungi representing different lignocellulose decay types was screened for oxidative biodegradation of the polymer polystyrene sulfonate (PSS). Brown-rot basidiomycetes showed PSS depolymerisation of up to 50 % reduction in number-average molecular mass (Mn) within 20 days. In-depth investigations with the most efficient depolymeriser, a Gloeophyllum trabeum strain, pointed at extracellular hydroquinone-driven Fenton chemistry responsible for depolymerisation. Detection of hydroxyl radicals present in the culture supernatants showed good compliance with depolymerisation over the time course of PSS degradation. 2,5-Dimethoxy-1,4-hydroquinone (2,5-DMHQ), which was detected in supernatants of active cultures via liquid chromatography and mass spectrometry, was demonstrated to drive the Fenton processes in G. trabeum cultures. Up to 80% reduction in Mn of PSS where observed when fungal cultures were additionally supplemented with 2,5-dimethoxy benzoquinone, the oxidized from of 2,5-DMHQ. Furthermore, 2,5-DMHQ could initiate the Fenton's reagent-mediated PSS depolymerisation in cell-free systems. In contrast, white-rot fungi were unable to cause substantial depolymerising effects despite the expression of lignin-modifying exo-enzymes. Detailed investigations with laccase from Trametes versicolor revealed that only in presence of certain redox mediators limited PSS depolymerisation occurred. Our results indicate that brown-rot fungi might be suitable organisms for the biodegradation of recalcitrant synthetic polymeric pollutants.

No MeSH data available.


Related in: MedlinePlus