7th joint conference "Joint Microbiology & Infection Conference 2024" of the DGHM and VAAM

Prof. Dr.

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Professor

Abstract: Terrestrial ecosystems are exposed to extensive pollution with microplastics (MP), with agricultural practices and unintentional dispersal especially impacting arable soils. A profound understanding of the interactions of MP with physical, chemical, and microbial factors in agricultural soils is critical to assess impacts on crop production. Our research, as part of the Collaborative Research Center 1357 “Microplastic” at the University of Bayreuth, aims to elaborate a comprehensive insight into the response of prokaryotic and fungal soil microbiota to MP pollution. We employ environmental samples, bench-scale microcosms, and controlled greenhouse experiments to determine MP-induced alterations in the overall taxonomic and functional diversity of soil- and plant-associated microbiota, as well as changes in soil biogeochemical parameters and processes. In soil microcosms, we show that soil microbes tend to be more clearly responsive to biodegradable vs. conventional plastics, but that effects vary with soil type. Next, maize (Zea mays) and strawberries (Fragaria × ananassa) were cultivated in soils amended with different types of conventional (LDPE, PET, PS) or biodegradable (PBAT) MP. The results reveal a distinct influence of plant hosts on prokaryotic soil microbiomes, largely overruling direct impacts of MP in both plant systems. However, variations in alpha diversity were evident, depending on the plant species, root proximity, and also on some, but not all plastic types. Interestingly, the degree of mycorrhization of maize plants was markedly reduced only for one polymer type. Our ongoing work aims to unravel the metabolic potential and functional context of microbial taxa most responsive to plastic amendment. We also discuss a polymer-specific approach towards extracting and characterizing environmental plastisphere microbiota, based on isopycnic density separation. Overall, our research within the CRC “Microplastic” advances the curent understanding of the intricate interplay between soil, soil microbes and microplastics as soil pollutant. This is an important contribution to the development of sustainable management strategies for soils and agroecosystems. 

Studying the impacts of microplastics on microbes in agricultural soil

Environmental Microbiology & Processes

Invited Talk

Metagenomics of the open ocean Plastisphere: a novel microbial niche with unique functional potential

IntroductionPlastic pollution in the oceans has become a major concern and focus of research in the last decades. Research so far has focused on the distribution of plastics and the taxonomic composition of the microbes living on plastic particles (termed Plastisphere). However, a functional understanding of the Plastisphere is lacking and thus its impact on global ecosystem functioning is unknown.GoalsThe aim of this study was to examine the functional potential and genetic adaptation of the open ocean Plastisphere based on a comparative metagenomics study with the surrounding seawater microbiome. Materials &amp; MethodsPlastic particles were collected from the North Atlantic and North Pacific Garbage patch on research cruises in summer 2019. Metagenomic DNA samples were extracted and sequenced. The resulting sequencing data was differentially binned into bacterial metagenome-assembled genomes (MAGs). The MAGs were used for Hidden Markov Model profiling utilizing public KEGG profiles of metabolic pathways, nitrogen cycling and others relevant for a surface-attached lifestyle in the oligotrophic open ocean.ResultsMore than 1700 Plastisphere MAGs were reconstructed and compared to &gt;450 corresponding seawater MAGs from the Tara Oceans project. The Plastisphere displayed a distinct microbiome that is similar across ocean basins and different to the surrounding seawater on the taxonomic class level. The Plastisphere further contains a higher genomic potential for coping with UV induced stress, as well as for diverse carbon utilization pathways, nitrogen fixation and uptake of essential elements (Ni, Po).SummaryThe open ocean Plastisphere is a complex assemblage of auto- and heterotrophic bacteria which appears to select for bacteria capable to cope with different stressors as well as having high metabolic flexibility. Our metagenomic study highlights that the open ocean Plastisphere displays a distinct functional profile, enabling microbes to thrive in an oligotrophic ocean.

Oral Presentation

Abstract: Microplastic particles ubiquitously found in the environment are taken up by many organisms. Subsequently, microplastic particles can translocate from the primarily exposed organs, e.g., the gastrointestinal tract or the respiratory organs, into the tissues, likely through cellular internalization. The reasons for cellular internalization are still largely unknown since this has only been shown for specifically surface-functionalized particles. We show that environmentally exposed microplastic particles are internalized into macrophages significantly more often than pristine microplastic particles. We identified biomolecules and microbial biofilms forming an eco-corona on the surface of microplastic particles, suggesting that environmental exposure promotes the cellular internalization of microplastics. Subsequently, we thoroughly analyzed the eco-corona originating from freshwater and saltwater to understand its role in particle-cell interactions better. We found the zeta potential to be increased due to the coating with an eco-corona, alongside with structural biofilm distinctions, which can be one driving factor for enhanced particle-cell interaction. Our results help better understand the particle-cell interaction mechanisms of environmentally exposed microplastic particles. Cellular internalization is a key route by which microplastic particles translocate into tissues, which may cause toxicological effects that affect environmental and human health.

The eco-corona on microplastic particles enhances their interactions with cells

Plastic mineralization by the sooty-mold fungus Capnodium coffeae demonstrated by isotope-tracing and -probing approaches

Plastic pollution represents an increasing environmental burden. Modification of plastic surfaces and degradation by microbes contributes to the removal of plastic from the environment. However, plastic mineralizing organisms are rare, and often mis-classified as such, probably due to the lack of standards. We hypothesize that hydrophobic, waxy surfaces found on tropic leaves that mimic plastic surfaces in terms of hydrophobicity are reservoirs of plastic degrading microbes and developed a standard procedure to unambiguously demonstrate plastic mineralization 1. A strain of the sooty-mold fungus Capnodium coffeae was isolated and tested on media amended with different plastics resulting in enhanced growth with polystyrene and other common plastics. Capnodium coffeae was incubated together with 13C-labelled polystyrene and 13CO2 emissions were followed via cavity ring-down spectroscopy. A continuous increase of polystyrene derived 13CO2 was observed in the headspace indicating polystyrene mineralization. Phospholipid fatty acids stable isotope probing indicated incorporation of polystyrene 13C into the fungal biomass and substantiated the polystyrene mineralizing capabilities of C. coffeae. Thus, we successfully isolated a polystyrene mineralizing fungus, and provide a strategy for the assessment of various microbial plastic metabolizers.1 Rohrbach, S., Gkoutselis, G., Mauel, A., Telli, N., Senker, J., Ho, A., G. Rambold and M.A. Horn. 2024. Setting new standards: Multiphasic analysis of microplastic mineralization by fungi. Chemosphere 349: 141025. DOI: 10.1016/j.chemosphere.2023.141025

Interactions Between High Load of a Bio‑based and Biodegradable Plastic and Nitrogen Fertilizer Affect Plant Biomass and Health: A Case Study with Fusarium solani and Mung Bean (Vigna radiata L.)

Bio-based and biodegradable plastics such as mulching films are widely used in agricultural field sites. However, there are limited studies of their impact on plant development and health even though an important soil-borne plant pathogen F. solani has been reported to associate with various types of bio-based and biodegradable plastics, especially polybutylene succinate-co-adipate (PBSA). To evaluate the influence of PBSA amendment in soils on plant development and health, F. solani and mung bean (V. radiata) were used as models in a modified petri-dish test using soil suspensions. Mung bean seeds were incubated in suspensions with two dilutions (high vs. low dilution with low vs. high PBSA amendment) of soils preincubated 1 year with PBSA under different treatments (combinations of N fertilizer (ammonium sulfate) and PBSA load) in the modified petri dish test. Plant development and disease incidence were recorded with both microscopic and molecular techniques (specific PCR and Illumina amplicon sequencing). Treatment with PBSA and N fertilizer in non-sterile soil suspensions strongly increased the disease caused by F. solani on V. radiata at both low and high soil dilution. At high soil dilution, the F. solani disease incident was 67.5% while at the low dilution the disease incidence reached 92.5%. In contrast, in treatments PBSA but without N fertilizer, non F. solani disease was observed. Apart from F. solani infection, other soil fungi can also infect the mung bean seedlings, especially at low soil dilution levels. Nevertheless, based on this short-term study, we found no evidence that PBSA alone can significantly increase the overall disease incidence.

SFB Session
CRC Microplastic Session

Termin

Chair

Programm

SFB SessionCRC Microplastic Session

Termin

Chair

Programm

SFB Session
CRC Microplastic Session