EFFECT OF DIFFERENT NUTRIENT SOURCES IN THE BIOREMEDIATION OF SOILS CHRONICALLY CONTAMINATED WITH HYDROCARBONS AT CARLINI STATION, ISLA 25 DE MAYO, SOUTH SHETLAND ISLANDS, ANTARCTICA

JULIA VILLALBA PRIMITZ; SUSANA VÁZQUEZ; LUCAS RUBERTO; DÉBORAH COLMAN

San Miguel de Tucumán

Congreso; XII Congreso Argentino de Microbiología General; 2017

SAMIGE

The logistics involved in the operation of Antarctic stations and the development of scientific activitiesentail the risk of contamination by fuels. Previous studies have shown that biostimulation of soilschronically contaminated with Antarctic Gasoil (AGO) produces significant increases in the removal ofhydrocarbons (HC). In this work, we report on the effect of amendment with N and P in differentformulations: inorganic salts, NH4NO3 y Na2HPO4, with (IN) and without (ANA) oxygenation bymixing; Nitrofoska® granular fertilizer (NPK) and OSEII® commercial product (CP), on the efficiency ofHC removal from soils with chronic contamination by gasoil, compared to a system without nutrientaddition (CC). The soil was collected from an area affected by the dripping of a connection betweentwo diesel fuel pipes. Treatments were done in triplicate, simulating biopiles containing 15 kg of soil,which were sampled over 50 days, analyzing the changes in the bacterial communities involved andthe quality and quantity of the remaining HC. Total heterotrophic aerobic (THAB) and hydrocarbondegrading bacteria (THDB) counts were performed on CPS agar and Gasoil agar. The quantification ofhydrocarbons was performed by infrared spectrophotometry (modified ASTM D066 method) and byGC-FID. The V3-V4 region (GC-341F and 518R primers) of the 16S rRNA gene was partially amplifiedin all soil samples to obtain a fingerprinting of the bacterial communities by DGGE (45% -60%denaturing urea/formamide gradient, gels run at 60V and 65 °C for 16h). Both the presence ofnumerous bacterial populations and changes in their relative proportions in the community throughoutthe trial as well as the decrease in HC concentration in CC systems indicate that, even without nutrientaggregation, the native microbiota can metabolize HC with just aerating the soil and at the expense ofthe few available nutrients. However, biostimulated systems resulted in markedly higher HC removalwith respect to CC, with CP as the most efficient. Bacterial counts supported these results, showing agreater proportion of degrading populations in biostimulated systems. With respect to the communitiesinvolved, although it is expected that any intervention in the microenvironment of microorganisms willinfluence its structure, particularly the aggregate of inorganic salts (IN, ANA) and granular fertilizer(NPK) selected communities less diverse than in CC, while the addition of OSEII® (CP) product led tothe development of more diverse communities. Although natural attenuation contributes to the removalof HC in Antarctica, the activity of microorganisms plays a key role in accelerating this process, whichis important in Antarctica given the short periods in which the soils are thawed and accessible to carryout a treatment. The addition of nutrients to balance metabolism favors the biodegradation of HC andincreases their removal in shorter times.