Production and accumulation of surfactants during the chemical oxidation

a b s t r a c t A soil contaminated with polycyclic aromatic hydrocarbons (PAH) was treated in laboratory slurry reactors with three chemical oxidants: (1) modified Fenton chemistry (MFC) with hydrogen peroxide (HP), (2) MFC with calcium peroxide (CP) (Cool-Ox TM ), and (3) sodium persulfate activated with Fe chelated using ethylenediaminetetraacetic acid (EDTA). A bioreactor served as a control. Samples of slurry filtrate were tested to quantify emulsification of PAH and concentrations of bulk surfactants, using the critical micelle dilution method. All three oxidants produced surfactants reaching levels above the critical micelle concentration (CMC), though the surfactants were removed at the end of treatment. The surfactants emulsified the PAH, and resulted in greater overall removal of 5-and 6-ring PAH than biodegradation alone. Treatment with CP-MFC resulted in the highest concentration of surfactants (four times the CMC), the most emulsification of PAH, and the highest removal of 5-and 6-ring PAH. None of the chemical treatments significantly reduced counts of culturable heterotrophic microorganisms

Molecular Characterization of the Murine Neural Retina Leucine Zipper Gene, Nrl

The NRL gene (D14S46E) is expressed in cells of human retina and encodes a putative DNA-binding protein of the leucine zipper family. Here we describe the analysis of the murine homolog of the NRL gene, Nrl. Various cDNAs resulting from alternate polyadenylation are characterized. The deduced polypeptide sequence is highly conserved between mouse and human, with an identical basic motif and leucine zipper domain. The nucleotide sequences in the 5' and 3'-untranslated regions also show significant homology. The 3'-untranslated region contains a polymorphic AGG- trinucleotide repeat. The murine Nrl gene consists of three exons; of these, the first is untranslated. The 5'-upstream promoter region has no canonical TATA box, but contains consensus binding site sequences for several DNA-binding proteins. Analysis of RNA from adult mouse tissues confirms the retina-specific expression of Nrl. This study provides the basis for dissecting the cis -regulatory elements involved in the retina-specific expression and for the development of an experimental model to investigate the function or any diseases associated with this gene in humans.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30468/1/0000096.pd

Pyrosequence analyses of bacterial communities during simulated in situ bioremediation of polycyclic aromatic hydrocarbon-contaminated soil

Barcoded amplicon pyrosequencing was used to generate libraries of partial 16S rRNA genes from two columns designed to simulate in situ bioremediation of polycyclic aromatic hydrocarbons (PAHs) in weathered, contaminated soil. Both columns received a continuous flow of artificial groundwater but one of the columns additionally tested the impact of biostimulation with oxygen and inorganic nutrients on indigenous soil bacterial communities. The penetration of oxygen to previously anoxic regions of the columns resulted in the most significant community changes. PAH-degrading bacteria previously determined by stable-isotope probing (SIP) of the untreated soil generally responded negatively to the treatment conditions, with only members of the Acidovorax and a group of uncharacterized PAH-degrading Gammaproteobacteria maintaining a significant presence in the columns. Additional groups of sequences associated with the Betaproteobacterial family Rhodocyclaceae (including those associated with PAH degradation in other soils), and the Thiobacillus, Thermomonas, and Bradyrhizobium genera were also present in high abundance in the biostimulated column. Similar community responses were previously observed during biostimulated ex situ treatment of the same soil in aerobic, slurry-phase bioreactors. While the low relative abundance of many SIP-determined groups in the column libraries may be a reflection of the slow removal of PAHs in that system, the similar response of known PAH-degraders in a higher-rate bioreactor system suggests that alternative PAH-degrading bacteria, unidentified by SIP of the untreated soil, may also be enriched in engineered systems