Effect of Growing <i>Miscanthus x giganteus</i> on Soil Microbial Communities in Post-Military Soil

Growing a second generation energetic plant Miscanthus x giganteus (Mxg) in former military sites appears to be a promising way to use such areas with synergic phytoremediation of contaminants (organic pollutants, potential toxic metals). Effect of Mxg growth on soil microbial communities during a two-year pot experiment with real post-military soil (Sliač, Slovakia) and the effect of potential toxic metal concentration was studied by analyses of microbial activities and phospholipid fatty acids (PLFA). Year-on-year positive changes in microbial community structure and state were detected (higher ratios of G+/G&#8722; bacteria and fungal/bacterial PLFA, and a decrease of stress indicators trans/cis and cy/pre PLFA). Portion of gram-positive bacteria correlated negatively with potential toxic metal concentrations; however, the concentration of potential toxic metals was not identified as the main stress factor&#8212;the access to bioavailable nutrients was more important. Overall, Mxg growth generally exhibited a positive effect on soil microorganisms

Biodegradation of High Concentrations of Aliphatic Hydrocarbons in Soil from a Petroleum Refinery: Implications for Applicability of New Actinobacterial Strains

At present, there is great demand for new resistant and metabolically active strains of biodegrading bacteria capable of degrading high concentrations of petroleum pollutants. In this study, we undertook a series of pot-based biodegradation experiments on soil from a petroleum refinery lagoon heavily polluted with aliphatic hydrocarbons (81.6 &plusmn; 2.5 g&middot;kg&minus;1 dry weight) and metals. Periodical bioaugmentation with either a mixture of isolated degraders identified as Bacillus sp. and Ochrobactrum sp. or biostimulation with nutrient medium, singly or in combination, did not produce any significant decrease in hydrocarbons, even after 455 days. Inoculation with Gordonia rubripertincta CWB2 and Rhodococcus erythropolis S43 in iron-limited media, however, resulted in a significant decrease in hydrocarbons 45 days after bioaugmentation. These actinobacterial strains, therefore, show significant potential for bioremediation of such highly polluted soils