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Composts are often highly contaminated with microplastic (MP) of different polymer types and shapes. Being used for various (agricultural) applications, composts are an entry pathway of MP in terrestrial ecosystems. Microplastic particles found in composts are coated with a biofilm due to previous exposure and treatment in biowaste plants. It has been shown that pristine microplastics impact terrestrial organisms on a sublethal level. Until now it remains unexplored how composted polymers affect organisms especially in contrast to pristine MP. Both the compost worm Eisenia fetida and the woodlouse Porcellio scaber encounter those composted MP during food uptake. As they differ in behaviour and diet the effect of MP can differ between organisms. Therefore, we studied the effect of composted and pristine MP in an environmentally relevant concentration on the life-history and oxidative stress levels of E. fetida and P. scaber. We tested three different polymer types (PS, PE and PLA) as fragments and fibres. To understand possible mechanisms behind the observed effects we also characterized the formatted MP biofilm composition via 16SrRNA (bacteria) and ITS (fungi) amplicon sequencing. Interestingly, we found contrasting effects on the organisms. Exposure to composted MP fragments induced a higher weight gain and reproductive output in E. fetida. Oxidative stress was higher for worms incubated in pristine MP while we found no effect for worms in the composted treatments. In contrast P. scaber gained less weight and had higher oxidative stress ingesting food with composted MPs while no effect was found for pristine MP. Also see: https://micro2022.sciencesconf.org/428085/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Background and novelty Due to its worldwide spread, microplastic (size range: 1 µm – 5 mm) has become a major concern in the past decade. It is proven, that microplastic particles (MP) accumulate in the food chain and most probably enter the human body via this path as well. After absorption (i.e., through the gastro-intestinal or pulmonary pathway), MP might be transferred more deeply into tissues increasing the potential of hazardous effects, e.g. local inflammation as well as cellular uptake associated with disturbance of the cellular homeostasis. Numerous studies in the recent years analysed the effect of commercial MP in vitro using model cell lines. Surprisingly, the results showed different and often even contradictory outcomes even when same polymers or size ranges were used. In our work, we aimed to correlate cellular uptake and induced biological responses with well-characterized physico-chemical properties of MPs (e.g., surface chemistry and size range) Results and discussion Uptake as well as noxiousness of particles were hereby highly dependent on their physico-chemical properties and also cell type-related. While epithelial cells showed only little PCI, macrophages engulfed a high number of particles. This interaction process is proved to be size-dependent and related to the respective surface charge. Interestingly, not only surface charge but also the surface charge density plays a crucial role for PCI. Subsequently, the number of engulfed MPs critically influenced the intensity of induced biological responses. While there was little to non-noxiousness effects of the particles to epithelial cells, macrophages showed a PCI-dependent noxiousness in various biological effects. Furthermore, besides surface chemistry, MP morphology and weathering status seemed to play an important role in inducing noxious effects at a wide level of biological effects. Also see: https://micro2022.sciencesconf.org/427172/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

Additional file 1: Figure S1. SMFC performance profile at different electrode spacings, substrate feeding intervals and electrode materials. (a) OCV from first block, the arrow shows point of first substrate feeding; (b) OCV from second block; (c) maximum power trends of the two blocks combined. The trends shown with dotted lines represent CF electrodes. Please refer to Table 1 of the main document for details of the different levels of the variables. Figure S2. Nyquist plots and the fits of SEC–MFCs at different electrode spacing: 2 h, 4 h and 8 h are SEC–MFCs at electrode spacing (ES) of 2, 4 and 8 cm, respectively. Figure S3. Nyquist plots of CF–MFCs at ES of 2, 4 and 8 cm, respectively (N:B Graphs were copied directly from EC-lab V11.32, where the fitting was performed). Figure S4. Taxonomic distribution of the 16S rDNA microbial community profile at the Phylum level. Table S1. Analysis of variance table for the model design. Table S2. Solutions for 2 combinations of categoric factor level. Table S3. Pairwise permanova results based on beta-group-significance (α = 0.05).

Additional file 3: Figure S3. Comparison between promoter motives of TSS located within (inMAI) and outside (exMAI) of the magnetosome island, cultivated under anoxic (0% dO2) and oxic (95% dO2) conditions. The motif logos were created with Weblogo [58].

Additional file 1: Figure S1. Cell growth and magnetic response (Cmag) under A) anoxic (dO2 0%, 10 mM nitrate), B) oxic (dO2 95%, 4 mM ammonium), C) microoxic (dO2 1%, 4 mM nitrate), D) oxic with nitrate (dO2 95%, 4 mM nitrate) conditions. (Scale bar 1 μm). Growth (black and grey lines) and Cmag (colored lines) were depicted for each replicate (circles, diamonds and triangles). The black arrow indicates the sampling timepoint for the RNA-seq experiments.

Additional file 4: Figure S2. Distribution of classified transcription start sites (TSS) under anoxic (0% dO2) and oxic (95% dO2) conditions in the whole genome (pTSS, primary TSS; asTSS, antisense TSS; iTSS, intragenic TSS; oTSS; other TSS).