Grasses andRhodococcuserythropolisBacteria for Bioremediation of Naturally Polluted Soils with Hydrocarbons

Biochemical tests to determine the biodegradability potential of bacterial strains in PAH polluted sites

Although the use of degrading-bacteria is one of the most efficient methods for the bioremediation of polluted sites, detection, selection and proliferation of the most efficient and competing bacteria is still a challenge. The objective of this multi-stage research was to investigate the effects of the selected bacterial strains on the degradation of anthracene, florentine, naphthalene, and oil, determined by biochemical tests. In the first stage, using the following tests: (a) biosurfactant production (emulsification, oil spreading, number of drops, drop collapse, and surface tension), (b) biofilm production, (c) activity of laccase enzyme, and (d) exopolysaccaride production, the three bacterial strains with the highest degrading potential including Bacillus pumilus, B. aerophilus, and Marinobacter hydrocarbonoclasticus were chosen. In the second stage using the following tests: (a) bacterial growth, (b) laccase enzyme activity, and (c) biosurfactant production (emulsification, oil spreading, and collapse of droplet) the degrading ability of the three selected bacterial strains plus Escherichia coli were compared. Different bacterial strains were able to degrade anthracene, florentine, naphthalene, and oil by the highest rate, three days after inoculation (DAI). However, M. hydrocarbonoclasticus showed the highest rate of florentine degradation. Although with increasing pollutant concentration the degrading potential of the bacterial strains significantly decreased, M. hydrocarbonoclasticus was determined as the most efficient bacterial strain.