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Published on: June 23, 2022
Hydrophobins from Aspergillus Mediate Fungal Interactions with Microplastics
Ross R Klauer1, Rachel Silvestri1, Hanna White1
1Chemical and Biomolecular Engineering, University of Delaware, 150 Academy St., Newark, Delaware 19716, United States.
Abstract:
Microplastics cause negative environmental consequences such as the release of toxic additive leachates, increased greenhouse gas emissions during degradation, and threaten food chains. Microplastic particles are known to serve as a vector for the transport of microbes (fungi and bacteria) to new environments, threatening biodiversity. Robust biofilm formation makes fungi candidates for collecting and remediating environmental microplastics. However, fungal-microplastic colonization mechanisms have not yet been explored. In this work, we aim to understand which fungal molecules mediate microplastic binding. We examine the common fungal genus Aspergillus, which we found binds microplastics tightly, removing particles from suspension. Upon inoculation of Aspergilli with microplastic particles, up to 3.85 ± 1.48 g of microplastics were flocculated per gram of dry fungal biomass; this phenomenon was observed across various plastics ranging in size from 0.05 to 5 mm. Gene knockouts revealed that hydrophobins drive microplastic-fungi binding, evidenced by a decrease in flocculation relative to that of wild-type Aspergillus fumigatus. Moreover, purified hydrophobins flocculated microplastics independently of the fungus, validating their ability to bind to microplastics. Our work elucidates a role for hydrophobins in fungal colonization of microplastics and highlights a target for mitigating the harm of microplastics through engineered fungal-microplastic interactions.
Insights
Fungi, particularly Aspergillus, can bind and remove microplastics from water. Specific fungal molecules called hydrophobins are key to this microplastic-fungi interaction, offering a new remediation strategy.
Area of Science:
- Environmental Science
- Microbiology
- Biotechnology
Background:
- Microplastics pose significant environmental threats, including toxic leachate release and microbial transport, impacting ecosystems and food chains.
- Fungi, known for robust biofilm formation, are potential agents for microplastic remediation, but the mechanisms of their interaction remain unclear.
Purpose of the Study:
- To investigate the molecular mechanisms underlying fungal binding and flocculation of microplastic particles.
- To identify specific fungal molecules responsible for mediating the interaction between fungi and microplastics.
Main Methods:
- Quantified microplastic flocculation by the common fungal genus *Aspergillus* across various plastic sizes.
- Utilized gene knockout experiments in *Aspergillus fumigatus* to identify key molecules involved in microplastic binding.
- Purified and tested the microplastic-binding capacity of identified fungal molecules independently.
Main Results:
- *Aspergillus* species effectively flocculated microplastics, removing up to 3.85 g of plastic per gram of fungal biomass.
- Gene knockouts demonstrated that hydrophobins are essential for the tight binding of microplastics to fungi.
- Purified hydrophobins alone were sufficient to flocculate microplastics, confirming their direct binding capability.
Conclusions:
- Hydrophobins play a crucial role in the colonization of microplastics by fungi.
- This research identifies hydrophobins as a target for developing engineered fungal-microplastic interactions for environmental remediation.
