Reintroducing plant coverage in a tropical wetland contaminated with oil and sulfate: rhizosphere effects on Desulfovibrio populations

The Mexican tropical wetland is a coastal system with capacity to support the contamination derived from the extractive industry and the transformation of crude oil, due to its high plant biodiversity and the presence of rhizospheric reducing sulphate bacteria from plants tolerant to crude oil. A field experiment was carried out for nine months to evaluate the adaptation of aquatic plants Leersia hexandra grass and Eleocharis palustris spikerush reintroduced in a wetland contaminated with 75 560 to 118 789 mg kg-1 of weathered petroleum and also with sulfate, derived from oil and gas pipeline leaks, and gaseous emissions. The effect of the weathered oil and sulfate on the dry matter production and the population density of the bacterium Desulfovibrio spp, isolated from the rhizosphere and soil of both plants, were evaluated. The means of the variables had statistical differences (p< 0.05). Weathered oil inhibited dry matter production of L. hexandra but not E. palustris; the effect of petroleum on Desulfovibrio density was very significant negative in the rhizosphere and in the soil of both plants. Sulfate reduced the dry matter of grass. The exposure of Desulfovibrio to sulfate significantly reduced its density in rhizosphere and soil (p< 0.01). We recommend the use of E. palustris for the decontamination of flooded soils contaminated with weathered oil and sulfate. Rev. Biol. Trop. 66(2): 908-917. Epub 2018 June 01.