The bioavailability of metals can be influenced not only by soil properties but also by other species living at polluted sites. However, in laboratory experiments, usually only one test species is used to estimate bioavailability. In this study, a two-species approach was applied to assess the impact of the earthworm Lumbricus rubellus on the bioavailability of cadmium and lead to the springtail Folsomia candida using natural soils from a gradient of metal pollution. Earthworms were kept in half of the soil replicates for 4 weeks. Subsequently, the uptake and elimination kinetics of cadmium and lead in F. candida exposed for 21 days to the soils was determined. Earthworm activity affected soil properties but did not significantly affect metal uptake rate constants in springtails. The slightly higher uptake due to the presence of earthworms, which was consistent in all tested soils and for both metals, suggests that further research is needed on the role of species interactions in affecting metal bioavailability in soil.
- MeSH
- ampicilin analogy a deriváty chemie MeSH
- biologická dostupnost MeSH
- členovci chemie účinky léků MeSH
- kadmium chemie farmakologie MeSH
- kinetika MeSH
- Oligochaeta účinky léků MeSH
- olovo chemie farmakologie MeSH
- půda MeSH
- znečištění životního prostředí MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Bio-artificial polymeric systems are a new class of polymeric constituents based on blends of synthetic and natural polymers, designed with the purpose of producing new materials that exhibit enhanced properties with respect to the individual components. In this frame, a combination of polyvinyl alcohol (PVA) and chitosan, blended with a widely used antibiotic, sodium ampicillin, has been developed showing a moderate behavior in terms of antibacterial properties. Thus, aqueous solutions of PVA at 1 wt.% were mixed with acid solutions of chitosan at 1 wt.%, followed by adding ampicillin ranging from 0.3 to 1.0 wt.% related to the total amount of the polymers. The prepared bio-artificial polymeric system was characterized by FTIR, SEM, DSC, contact angle measurements, antibacterial activity against Staphylococcus aureus and Escherichia coli and antibiotic release studies. The statistical significance of the antibacterial activity was determined using a multifactorial analysis of variance with ρ < 0.05 (ANOVA). The characterization techniques did not show alterations in the ampicillin structure and the interactions with polymers were limited to intermolecular forces. Therefore, the antibiotic was efficiently released from the matrix and its antibacterial activity was preserved. The system disclosed moderate antibacterial activity against bacterial strains without adding a high antibiotic concentration. The findings of this study suggest that the system may be effective against healthcare-associated infections, a promising view in the design of novel antimicrobial biomaterials potentially suitable for tissue engineering applications.
- MeSH
- ampicilin * chemie farmakologie MeSH
- antibakteriální látky * chemická syntéza chemie farmakologie MeSH
- chitosan * chemie farmakologie MeSH
- Escherichia coli růst a vývoj MeSH
- polyvinylalkohol * chemie farmakologie MeSH
- Staphylococcus aureus růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
Volatiles produced by bacterial cultures are known to induce regulatory and metabolic alterations in nearby con-specific or heterospecific bacteria, resulting in phenotypic changes including acquisition of antibiotic resistance. We observed unhindered growth of ampicillin-sensitive Serratia rubidaea and S. marcescens on ampicillin-containing media, when exposed to volatiles produced by dense bacterial growth. However, this phenomenon appeared to result from pH increase in the medium caused by bacterial volatiles rather than alterations in the properties of the bacterial cultures, as alkalization of ampicillin-containing culture media to pH 8.5 by ammonia or Tris exhibited the same effects, while pretreatment of bacterial cultures under the same conditions prior to antibiotic exposure did not increase ampicillin resistance. Ampicillin was readily inactivated at pH 8.5, suggesting that observed bacterial growth results from metabolic alteration of the medium, rather than an active change in the target bacterial population (i.e. induction of resistance or tolerance). However, even such seemingly simple mechanism may provide a biologically meaningful basis for protection against antibiotics in microbial communities growing on semi-solid media.
- MeSH
- amoniak metabolismus MeSH
- ampicilin chemie farmakologie MeSH
- antibakteriální látky chemie farmakologie MeSH
- koncentrace vodíkových iontů MeSH
- kultivační média chemie metabolismus MeSH
- mikrobiální testy citlivosti MeSH
- rezistence na ampicilin MeSH
- Serratia účinky léků růst a vývoj metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- ampicilin farmakologie chemie MeSH
- antibakteriální látky farmakologie chemie MeSH
- cefalosporiny farmakologie chemie MeSH
- cefamyciny farmakologie chemie MeSH
- karbapenemy farmakologie chemie MeSH
- laktamy MeSH
- rezistence na penicilin MeSH
- sulbaktam farmakologie chemie MeSH
- Publikační typ
- přehledy MeSH
