“Estudio del desarrollo de comunidades microbianas degradadoras de fenantreno adsorbido a un soporte de poliestireno como modelo del suelo.”

ANA M. LÓPEZ, A. BOSCH, O. M. YANTORNO, M. T. DEL PANNO

Villa Carlos Paz, Córdoba, Argentina

Congreso; VI Congreso Argentino de Microbiología General; 2009

Sociedad Argentina de Microbiología General (SAMIGE)

Study of a phenanthrene-degrading community in a simple soil model. Ana M. López*, M. A. Bosch, O. M. Yantorno, M. T. Del Panno. CINDEFI (CCT-UNLP) Calle 50 y 115, (1900) La Plata, Argentina. *anitamisiones@hotmail.com The polycyclic aromatics hydrocarbons (PAH) are relevant environmental contaminants due to their toxicity, mutagenesis and carcinogenesis properties. The principal process of PAH degradation in the environment is done by the microorganisms, involving the selection of populations with specifics degrading capabilities. The PAH biodegradation in soil is affected by their low bioavailability, due to their low water solubility and their tendency to be adsorbed to the soil organic matter.With the aim to know the microbial communities growth in soil chronically contaminated with PHA, a simple model solid phase preloaded with phenanthrene was studied. We describe a study using Amberlite XAD2 (Sigma), a porous resin of polystyrene, in bath system with liquid mineral medium (LMM). The adsorption capacity of the model was 10.87 mg of phenanthrene/g of XAD2 and the phenanthrene desorption was less than 7% after 30 days of incubation under abiotic condition. An enrichment culture of phenanthrene degrading bacteria was obtained by using a petrochemical contaminated soil. Duplicated batch systems were prepared by inoculation of 1ml of enrichment culture in 20 ml of LMM containing 2g of XAD2 preloaded with phenanthrene. The systems were incubated during 30 days at 28ºC. A 10% of colonized solid phase was removed, washed and transferred to fresh systems. As a whole four transfers were done. The growth was monitored by phenanthrene degrading bacteria counts and FT-IR from planktonic and sessile populations. An increase of three orders of magnitude was detected after the fourth transfer. The FT-IR analysis from the communities established in the third and fourth transfers showed differences in the carbohydrates region (1200-900cm-1). These differences could be seen in both the relative intensity of the bands respect to proteins (Amida II) and the peaks position. In the fourth transference, after 30days of incubation, an increase in the amida II:carbohydrate relation was detected in the sessile population. That increase was corresponded with an increase of the sessile degrading population.The adhesion to XAD2 without phenanthrene of the cells culture was determined. A 10% of colonized solid phase from fourth transfer was removed, washed and inoculated in fresh systems to study the changes in the community during the solid phase colonization. The colonization was monitored by PCR-DGGE method. The visual inspection of the gel demonstrated changes in the communities during the incubation. Some populations from the inoculum did not colonize the solid phase. While some others populations not detected in the inoculum, were detected during the incubation on the solid phase. This dynamic would be a consequence of the competence between degrading populations, which are expressing different strategies to promote the phenanthrene availability.