Endophytic bacteria with potential for bioremediation of petroleum hydrocarbons and derivatives
Endophytic microorganisms live inside plants and show no apparent damage for the host. They often assist in plants’ survival and facilitate their growth, or they can metabolize organic contaminants. This study aimed to isolate and identify the endophytic bacteria of plants present in impacted areas, as well as to test their ability in petroleum and their derivatives’ degradation. Plant samples were collected in an asphalt mud impacted area, and then they were superficially disinfected. After maceration and fragmentation, they were incubated at 30°C for about 72 h, when growth of microorganisms was observed in culture media. The verification of petroleum and derivatives degradation capacity was performed in ELISA plates, thereby exposing the bacteria to a solution of minimal medium, the dye DCPIP solution (2,6-dicloroindofenol sodium salt) and the petroleum or derivative tested (burning oil, lubricating oil, diesel oil and gasoline). A positive reading for degradation was observed by discoloration of DCPIP. Among nine bacteria tested, three showed degradative activity in different fractions of petroleum, diesel oil and gasoline, and others showed different profiles. Some isolates were identified from the sequencing of 16S DNA, after which they were diagnosed as Bacillus cereus, Staphylococcus pasteuri and Pseudomonas sp. The endophytic bacteria isolated from Cerrado plants confirmed their potential for application in bioremediation processes.
Key words: Endophytic microorganisms, petroleum, bioremediation, Cerrado.