Poblaciones microbianas en perfiles de suelos afectados por hidrocarburos del petróleo en el estado de tabasco, Mexico

Oil incorporation into the soil may generate modifications to the vertical distribution of bacteria and fungi populations. Many environmental contingencies occurs in the State of Tabasco by oil leakages and spills in the marshy soils, rivers, streams and lagoons. Although there are reports that explain the distribution pattern of bacteria and fungi populations across the soil profile related to soil organic matter and humidity, the effect caused by oil is unknown. Identification of layers and horizons of Gleysols (Endoaquents and Hydraquents) influenced by oil leakages and spills from pipelines and pits for oil-gas separation was performed at oil field La Venta and Complejo Procesador de Gas La Venta. Microorganisms were counted by means of the plate count technique on surface by dilutions, isolation of pure culture and isolate characterization. Soils have high contents of organic matter, nitrogen, phosphorus, potassium and high cationic exchange capacity. Soil humidity is above 100% in superficial and underlying horizons, with high contents of total petroleum hydrocarbons in superficial horizons and lower in the underlying. No correlation was found between microbial populations and soil organic matter or with total petroleum hydrocarbons; however, correlation was found with soil humidity in soil without contamination, and in soil with chronic contamination. Oil decreased drastically bacteria's and fungi populations in soil with chronic contamination. Significant correlation is present between microbial populations, organic matter, humidity and total petroleum hydrocarbons in soil with 115 211 mg kg ^-1 of total oil hydrocarbons.