Rhizosphere and Endophytic Bacteria Associated to Ocimum basilicum L. with Decaclorobiphenyl Removal Potential

摘要

Basil (Ocimum basilicum L.) is a hyperaccumulative herbaceous plant that has the ability to grow in contaminated soils and is believed to harbor a wide variety of bacterial species resistant to recalcitrant toxic chemical compounds. The objective of this work was to evaluate the potential for removal of decaclorobiphenyl PCB-209 by bacteria associated with the O. basilicum plant. A total of 34 endophytes and 52 strains from the rhizosphere of this plant were isolated using selective culture media. The adaptive capacity of the bacteria in phenol and Arochlor 1242 was initially determined and then a set of bacteria was selected and their removal potential of decachlorobiphenyl PCB-209 was evaluated. The phylogenetic analysis of 16S rRNA gene grouped to the O. basilicum isolates within bacterial genera Acinetobacter, Bacillus, Lysinibacillus, Novosphingobium, Pseudomonas, Rhizobium, Sphingobium, Stenotrophomonas, and Terribacillus as well as bacterial strains Pseudomonas taiwanensis BS-1, Rhizobium nepotum BS-2, Terribacillus sacharophilus BS-3, Stenotrophomonas rhizophila BS-4, Bacillus arybhattai BS-5, and Lysinibacillus macroides BS-6 showed the ability to adapt and use phenol and Arochlor 1242 as source of C. The strains BS-4 isolated from the root of the plant showed a higher potential from the removal of the PCB-209 (390.75 mg L-1) at an initial concentration of 500 mg L-1 and also had the ability to synthesize biosurfactant (EI = 60%) compared to the other strains evaluated. The diversity of bacteria associated to O. basilicum had biological qualities that may contribute to their adaptation and proliferation in an environment contaminated by PCB and be used efficiently as bioremediation to relieve agricultural soils contaminated by persistent organic compounds.