FORMATION OF MICROBIAL COMMUNITIES IN OIL SHALE CHEMICAL INDUSTRY SOLID WASTES DURING PHYTOREMEDIATION AND BIOAUGMENTATION
Oil shale thermal processing has resulted in solid waste dump sites containing up to 100 million tons of solid waste. The processed oil shale contains complex mixture of organic and inorganic compounds and is highly toxic. Laboratory and field experiments were carried out in order to test the effect of phytoremediation and bioaugmentation for remediation of pollutants in semi-coke. Microbial community of aged (ca 10 ten years) semi-coke is characterized by few dominant populations and possesses low diversity. Changes in microbial community structure and activity occurred in semicoke as a result of phytoremediation and bioaugmentation. The phytoremediation increased the number of bacteria and diversity of microbial community in semi-coke as well as microbial biomass. The general trend was the increase of proportion of biodegradable bacterial numbers within microbial community due to the treatment. Highest values for all measured microbiological parameters were found in rhizosphere samples. Within a two and half year period starting from establishment of test plots, the concentration of phenolic compounds decreased up to 100% and oil products more than three times at plots with vegetation compared to control. Bacterial biomass consisting of three bacterial strains was applied to three experimental plots. These three bacterial strains Pseudomonas mendocina PC1, P. fluorescens PC24 and P. fluorescens PC18 degrade phenols via catechol meta, catechol or protocatechuate ortho or via the combination of catechol meta and protocatechuate ortho pathways, respectively. Bioaugmentation increased biodegradation intensity of oil products up to 50% compared to untreated planted controls and enhanced plant growth, but the effect of bioaugmentation on microbial community parameters was shortterm. Our results indicate that increased biodegradation activity was due to proliferation of specific microbial groups, changes in taxonomic diversity of bacterial community and catabolic genes.
KeywordsMicrobial Community Catabolic Gene Untreated Plot Rhizosphere Sample Pseudomonas Mendocina
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