Biodegradable polymers boost reproduction in the earthworm Eisenia fetida.

Microplastic contamination in soil has become a global environmental threat as it adversely affects terrestrial organisms like earthworms as well as soil properties. Especially biodegradable polymers have recently been used as an alternative to conventional polymer types, although their impact remains poorly understood. Thus, we studied the effect of conventional (polystyrene: PS, polyethylene terephthalate: PET, polypropylene: PP) versus aliphatic polyesters classified as biodegradable polymers (poly-(l-lactide): PLLA, polycaprolactone: PCL) on the earthworm Eisenia fetida and soil properties (pH and cation exchange capacity). We addressed direct effects on the weight gain and reproductive success of E. fetida, and indirect effects, like changes in the gut microbial composition as well as the production of short-chain fatty acids by the gut microbiota. Earthworms were exposed for eight weeks in an artificial soil amended with two environmentally relevant concentrations (1 % and 2.5 % (w/w)) of the different microplastic types. PLLA and PCL boosted the number of cocoons produced by 135 % and 54 %, respectively. Additionally, exposure to these two polymers increased number of hatched juveniles, changed gut microbial beta-diversity, and increased the production of the short chain fatty acid lactate compared to the control treatments. Interestingly, we also found a positive effect of PP on the earthworm's bodyweight and reproductive success. The interaction of microplastic and earthworms decreased soil pH by about 1.5 units in the presence of PLLA and PCL. No polymer effect on the cation exchange capacity of soil was found. In general, neither the presence of conventional nor biodegradable polymers had any adverse effects on any of the studied endpoints. Our results suggest that the effects of microplastic highly depend on the polymer type, and that the degradation of biodegradable polymers might be enhanced in the gut of earthworms, which implies that they may use biodegradable polymers as a potential carbon source.

Mitomycin C-induced effects on aerobic methanotrophs in a landfill cover soil; implications of a viral shunt?

A viral shunt can occur when phages going through a lytic cycle, including lysogenic phages triggered by inducing agents (e.g. mitomycin C), results in host lysis and the release of cell constituents and virions. The impact of a viral shunt on the carbon, including methane cycle in soil systems is poorly understood. Here, we determined the effects of mitomycin C on the aerobic methanotrophs in a landfill cover soil. To an extent, our results support a mitomycin C-induced viral shunt, as indicated by the significantly higher viral-like particle (VLP) counts relative to bacteria, elevated nutrient concentrations (ammonium, succinate), and initially impaired microbial activities (methane uptake and microbial respiration) after mitomycin C addition. The trend in microbial activities at <2 days largely corresponded to the expression of the pmoA and 16S rRNA genes. Thereafter (>11 days), the active bacterial community composition significantly diverged in the mitomycin C-supplemented incubations, suggesting the differential impact of mitomycin C on the bacterial community. Collectively, we provide insight on the effects of mitomycin C, and potentially a viral shunt, on the bacteria in the soil environment.

Detection and identification of Staphylococcus aureus using magnetic particle enhanced surface plasmon spectroscopy.

In this work, an approach for SPR spectroscopy using the liSPR system is examined that combines signal amplification by PCR and magnetic nanoparticles in one injection step. Therefore, the synthesis of PCR products was performed on the beads similar to a solid-phase PCR, termed PCR-on-a-bead. The functionality of this PCR was proven using an enzymatic assay. For validation the detection of oligonucleotides by SPR, an asymmetric PCR product was investigated. A signal increase upon binding of the PCR product to the specific probes was observed. In addition, surface regeneration of the chip was examined and reuse for at least two times ascertained. Amplification of the SPR signal by magnetic beads was verified but no signal was detected for PCR products immobilized on particles prior to injection.

Crystallographic analysis of Neisseria meningitidis PorB extracellular loops potentially implicated in TLR2 recognition.

Among all Neisseriae species, Neisseria meningitidis and Neisseria gonorrhoeae are the only human pathogens, causative agents of bacterial meningitis and gonorrhoea, respectively. PorB, a pan-Neisseriae trimeric porin that mediates diffusive transport of essential molecules across the bacterial outer membrane, is also known to activate host innate immunity via Toll-like receptor 2 (TLR2)-mediated signaling. The molecular mechanism of PorB binding to TLR2 is not known, but it has been hypothesized that electrostatic interactions contribute to ligand/receptor binding. Strain-specific sequence variability in the surface-exposed loops of PorB which are potentially implicated in TLR2 binding, may explain the difference in TLR2-mediated cell activation in vitro by PorB homologs from the commensal Neisseriae lactamica and the pathogen N. meningitidis. Here, we report a comparative structural analysis of PorB from N. meningitidis serogroup B strain 8765 (63% sequence homology with PorB from N. meningitidis serogroup W135) and a mutant in which amino acid substitutions in the extracellular loop 7 lead to significantly reduced TLR2-dependent activity in vitro. We observe that this mutation both alters the loop conformation and causes dramatic changes of electrostatic surface charge, both of which may affect TLR2 recognition and signaling.