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A hardwood biochar was examined for its potential use as an amendment to aid in the phytostabilization of a severely-contaminated soil at a former sulfuric acid recycling factory site. The soil, which has remained unvegetated for nearly a century, contained high pseudo-total concentrations of lead, arsenic and antimony and was both highly acidic and hydrophobic due to the presence of petroleum-based acid tar. Three application approaches were tested with 10 and 20% (vol/vol) biochar: Incorporation into soil, top-dressing on the surface, and layering within the soil. The results suggest that the homogeneous mixing of the hardwood biochar into soil would not promote the long-term restoration at this site due to its inherently low alkalinity relative to the very high net acidity of the existing soil. In contrast, surface application of biochar resulted in the most successful growth of Canada wild-rye grass by exploiting the properties inherent to biochar alone. [ABSTRACT FROM AUTHOR]

Abstract: Culture-dependent DGGE (CD DGGE) fingerprinting of the 16S rRNA gene was used to characterize mixed bacterial communities recovered on agar plates. Using R2A Agar as a growth medium, CD DGGE analysis resulted in clear banding patterns of sufficient complexity (16–32 major bands) and reproducibility to investigate differences in bacterial communities in a silt loam soil. Replicate CD DGGE profiles from plates inoculated with less-dilute samples (10−3) had a higher band count and were more similar (72–77%) than profiles from more-dilute samples (51–61%). Different culture media and incubation conditions resulted in distinct community fingerprints and increased the cumulative number of unique bands detected. When CD DGGE fingerprints were compared to profiles constructed from 16S rRNA genes obtained from culture-independent clone libraries (CB DGGE profiles) 34% of the bands were unique to the culture-dependent profiles, 32% were unique to the culture-independent profiles and 34% were found in both communities. These data demonstrate that culture-independent DGGE profiles are supplemented by the distinct bands detected in culture-dependent profiles. CD DGGE can be a useful technique to follow the dynamics of distinct culturable fractions of the soil bacterial community. [Copyright &y& Elsevier]