Chromium-reducing microorganisms in bioremediation of heavy metals contaminated soil

Mnogobrojne industrijske aktivnosti, osim koristi za ljudsku populaciju, imale su za posledicu povećanje sadržaja teških metala i promene diverziteta živih organizama u životnoj sredini. Cilj ovog rada bio je ispitivanje uticaja visokih koncentracija teških metala na mikrobni diverzitet zemljišta i mogućnosti primene ekoremedijacionih tehnologija u cilju saniranja posledica industrijske aktivnosti. Istraživanja su obavljena na području bivše fabrike “Rog” (Ljubljana, Republika Slovenija). Ispitivanje mikrobnog diverziteta obavljeno je primenom standardnih metoda. Rezultati istraživanja ukazuju da je brojnost hrom-rezistentnih bakterija i gljiva bila različita i zavisila je od koncentracije hroma u podlozi, pH vrednosti podloge i lokacije uzorkovanja. Iz kontaminiranih uzoraka zemljišta, ukupno su izolovana 53 izolata hrom-rezistentnih bakterija. Među njima dominiraju gram-pozitivne štapićaste sporogene bakterije. Morfološkom i molekularnom identifikacijom bakterijski izolati su svrstani u rod Bacillus sp. Rast hrom-rezistentnih gljiva je zavisio od istih faktora kao i kod hrom-rezistentnih bakterija. Gljive su morfološki identifikovane i svrstane u rodove Alternaria sp., Fusarium sp. i Penicillium sp. Stepen redukcije Cr(VI) zavisio je od njegove početne koncentracije, bakterijskih izolata i vremena inkubacije. Svi bakterijski izolati su bili sposobni za kompletnu ili delimičnu redukciju različitih početnih koncentracija Cr(VI). Precizno morfološki okarakterisane i molekularno identifikovane mikrobne populacije u interakciji sa biljkama tolerantnim na prisustvo metala, predstavljaju nezamenljive karike bioremedijacionih tehnologija. Rezultati ove doktorske disertacije imaju, osim naučnog, i aplikativni značaj i mogu se primeniti u remedijaciji zemljišta kontaminiranih industrijskim otpadom.The numerous industrial activities, except of the benefits for the human population, resulted in an increase in the content of heavy metals and a change in the diversity of living organisms in the environment. The aim of this disertation was to examine the influence of high concentrations of heavy metals on the microbial diversity of the soil and the possibility of applying ecoremediation technologies in order to remedy the consequences of industrial activity. The research was carried out on the location of the former factory "Rog" (Ljubljana, Republic of Slovenia). Examination of microbial was carried out with using of standard methods. The results of the study indicate that the number of chromium-resistant bacteria and fungi was different and it depended on the concentration of chromium in the substrate, substrate pH and sampling location. From contaminated soil samples, 53 isolates of chromium-resistant bacteria were isolated. Among them, gram-positive rod-shaped spore-forming bacteria dominate. By morphological and molecular identification, bacterial isolates are classified into the genus Bacillus sp. The growth of chromium resistant fungi depend on the same factors as for chromium-resistant bacteria. Fungi have been morphologically identified and classified into the genus Alternaria sp., Fusarium sp. and Penicillium sp. The degree of reduction Cr (VI) depended on its initial concentration, bacterial isolates and incubation times. All bacterial isolates were capable of complete or partial reduction of different initial concentrations of Cr (VI). Precisely morphologically characterized and molecularly identified microbial populations interacting with plants tolerant to the presence of metals are irreplaceable players in bioremediation technologies. The results of this dissertation have scientific and applicative significance, and can be applied in the remediation of soil contaminated with industrial waste