Abstract
Polycyclic aromatic hydrocarbons (PAHs) are toxic, mutagenic and among the most damaging chemical compounds with regard to living organisms. Because of their persistence and wide distribution removal from the environment is an important challenge. Here we report a new Nano container matrix based on the deep sea archaea-derived RHCC-Nanotube (RHCC-NT), which rapidly and preferentially binds low molecular weight PAHs. Under controlled-laboratory conditions and using fluorescence spectroscopy in combination with X-ray crystallography and MD simulations, we quantified the real-time binding of low molecular weight PAHs (2–4 rings) to our substrate. Binding coefficients ranged from 5.4 ± 1.6 (fluorene) to 32 ± 7.0 μM (acenaphthylene) and a binding capacity of 85 pmoles PAH per mg RHCC-NT, or 2.12 μmoles in a standard 25 mg sampler. The uptake rate of pyrene was calculated to be 1.59 nmol/hr∙mol RHCC-NT (at 10 C). Our results clearly show that RHCC-NT is uniquely suited as a monitoring matrix for low molecular weight PAHs.
Highlights
Discovered growing on the periphery of deep-sea hydrothermal vents, Staphylothermus marinus is a heterotrophic hyperthermophilic archaea that requires elemental sulfur for growth
Transfer free energy based on molecular dynamics simulations and structural studies based on X-ray crystallography to determine the Polycyclic aromatic hydrocarbons (PAHs) location within the RHCC-NT
Fluorescence assays were used to examine the binding of RHCC-NT to PAHs as they allow discrimination between PAHs in solution and those bound to the RHCC-NT, as well as the ability to monitor PAH uptake as a function of time (Fig. 2)
Summary
Discovered growing on the periphery of deep-sea hydrothermal vents, Staphylothermus marinus is a heterotrophic hyperthermophilic archaea that requires elemental sulfur for growth. The ability of S. marinus to sequester elemental sulfur from its environment relies in part on the Right Hand Coiled-Coil Nanotube (RHCC-NT), a protein fragment in the surface layer of the microorganism. The RHCC-NT encapsulates elemental cyclo-octasulfur in a hydrophobic cavity with a diameter of ~8.4 Å, where it is available for metabolism These cavities, adapted to capture the small, hydrophobic cyclo-octasulfur are of a suitable size to encapsulate low molecular weight PAHs9. We studied the ability of the nanotube to uptake PAHs by using pyrene as a model compound. These binding experiments were coupled with calculations of the www.nature.com/scientificreports/. Our studies provide an insight for future binding site optimization within the nanotube, with the end goal to use it as a monitoring device in the field application
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