Fungal appressoria as mechanochemical organelles for polyurethane degradation
5 affiliations
- 1Laboratory of Experimental Marine Biology & Center of Deep Sea Research, Shandong Province Key Laboratory of Marine Biodiversity and Bio-resource Sustainable Utilization, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- 2Marine Academy of Zhejiang Province, Hangzhou, China
- 3Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, China
- 4College of Earth Science, University of Chinese Academy of Sciences, Beijing, China
- 5Key Laboratory of Ocean Space Resource Management Technology, Ministry of Natural Resources, Hangzhou, China
Abstract
Polyurethane (PU) is a synthetic polymer characterized by highly stable urethane linkages that hinder biological turnover. Although fungi have been implicated in PU degradation, the molecular mechanisms that couple polymer surface sensing to enzymatic depolymerization remain largely undefined. Here we show that the marine-derived fungus Alternaria alternata FB1 employs a surface-sensing signaling pathway that drives appressorium-mediated degradation of both polyester and polyether PUs. Contact with hydrophobic polymer surfaces rapidly induces melanized appressoria that mechanically penetrate the polymer matrix and promote its oxidative and hydrolytic depolymerization. Integrative transcriptomic analysis and targeted gene disruption identify the mucin-like surface sensor Msb2 as an upstream component of the polyurethane surface-sensing machinery. Loss of Msb2 disrupts MAPK and Ca2+ signaling, impairs appressorium differentiation, and reduces expression of degradative enzymes. Biochemical profiling further reveals multiple urethane-hydrolyzing enzymes that expand the known catalytic repertoire for PU bond cleavage. Together, these findings establish a mechanistic framework linking surface recognition, appressorium development, and polymer degradation, providing insight into how fungi transform recalcitrant polyurethane materials. Author summary: Plastics are now found in nearly every environment on Earth, yet most are extremely difficult for living organisms to break down. Polyurethane is one such plastic and is widely used in foams, coatings, and adhesives. While some fungi have been reported to degrade plastics, we still know little about how these organisms recognize synthetic materials and activate the cellular processes needed to transform them. In this study, we investigated how a marine fungus responds when it encounters polyurethane surfaces. We found that the fungus forms specialized structures normally used to penetrate plant tissues. These structures allow the organism to tightly attach to the plastic surface and concentrate enzymes that break chemical bonds within the material. Using genetic and transcriptomic approaches, we identified a membrane protein that acts as a sensor for hydrophobic surfaces and triggers a signaling pathway controlling this response. This pathway coordinates cellular differentiation and enzyme production, enabling the fungus to interact with and degrade polyurethane. Our findings reveal how existing fungal genetic programs can be redirected to interact with synthetic materials, providing new insight into the biological mechanisms that may influence the persistence of plastics in the environment.
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BibTeX
@article{fei2026fungal,
title = {{Fungal appressoria as mechanochemical organelles for polyurethane degradation}},
author = {Fan Fei and Zhenjie Su and Rui Liu and Rongrong Gao and Chaomin Sun},
journal = {PLOS Genetics},
year = {2026},
month = aug,
doi = {10.1371/journal.pgen.1012292},
url = {https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1012292},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Fungal appressoria as mechanochemical organelles for polyurethane degradation
AU - Fan Fei
AU - Zhenjie Su
AU - Rui Liu
AU - Rongrong Gao
AU - Chaomin Sun
PY - 2026
DA - 2026/08/31
JO - PLOS Genetics
DO - 10.1371/journal.pgen.1012292
UR - https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1012292
AB - Polyurethane (PU) is a synthetic polymer characterized by highly stable urethane linkages that hinder biological turnover. Although fungi have been implicated in PU degradation, the molecular mechanisms that couple polymer surface sensing to enzymatic depolymerization remain largely undefined. Here we show that the marine-derived fungus Alternaria alternata FB1 employs a surface-sensing signaling pathway that drives appressorium-mediated degradation of both polyester and polyether PUs. Contact with hydrophobic polymer surfaces rapidly induces melanized appressoria that mechanically penetrate the polymer matrix and promote its oxidative and hydrolytic depolymerization. Integrative transcriptomic analysis and targeted gene disruption identify the mucin-like surface sensor Msb2 as an upstream component of the polyurethane surface-sensing machinery. Loss of Msb2 disrupts MAPK and Ca2+ signaling, impairs appressorium differentiation, and reduces expression of degradative enzymes. Biochemical profiling further reveals multiple urethane-hydrolyzing enzymes that expand the known catalytic repertoire for PU bond cleavage. Together, these findings establish a mechanistic framework linking surface recognition, appressorium development, and polymer degradation, providing insight into how fungi transform recalcitrant polyurethane materials. Author summary: Plastics are now found in nearly every environment on Earth, yet most are extremely difficult for living organisms to break down. Polyurethane is one such plastic and is widely used in foams, coatings, and adhesives. While some fungi have been reported to degrade plastics, we still know little about how these organisms recognize synthetic materials and activate the cellular processes needed to transform them. In this study, we investigated how a marine fungus responds when it encounters polyurethane surfaces. We found that the fungus forms specialized structures normally used to penetrate plant tissues. These structures allow the organism to tightly attach to the plastic surface and concentrate enzymes that break chemical bonds within the material. Using genetic and transcriptomic approaches, we identified a membrane protein that acts as a sensor for hydrophobic surfaces and triggers a signaling pathway controlling this response. This pathway coordinates cellular differentiation and enzyme production, enabling the fungus to interact with and degrade polyurethane. Our findings reveal how existing fungal genetic programs can be redirected to interact with synthetic materials, providing new insight into the biological mechanisms that may influence the persistence of plastics in the environment.
SN - 1553-7404
ER -