Study of a bacterial consortium adapted to low bioavailability to phenanthrene, as potential inoculant to chronically PAH contaminated soils.

ANA MARIA LOPEZ; ROCIO MEDINA; ALEJANDRA BOSCH; OSVALDO M YANTORNO; MARIA TERESA DEL PANNO

Barcelona

Congreso; AquaConsoil Barcelona 2013; 2013

AquaConSoil

Polycyclic aromatic hydrocarbons (PAHs) are common environmental pollutants produced by industrial operations using fossil fuels as well as by natural events such as forest fires (Berthe- Corti et al. 2007). Microorganisms are the major agents mineralizing PAH in terrestrial environments, either using them directly as carbon and energy source or via co-metabolism - when other substrate constitute the primary carbon sourse (Ortega et al., 1998). Microbial transformations of PAHs do not only have a special impact in nature but they also play key roles in various technological applications of microorganisms, such as wastewater treatment, biodegradation, bioremediation, and biocatalysis. PAHs have a strong tendency to adsorb onto solid surfaces especially hydrophobic sites. A reduction in water concentration due to their adsorption can modify the accessibility and bioavailability of PAHs and thus, decrease or enhance their biodegradation (Semple et al., 2007). The establishment of microniches of PAH degrading bacteria in a PAH contaminated soil represents a process strongly influenced by both, the manner in which the PAH are exposure in the soil and bacterial capability to develop physiological strategies to adapt to the different PAH bioavailability (Johnsen et al., 2005). In order to reduce phenanthrene bioavailability to different degrees, Grosser and coworkers (Grosser et al., 2000) proposed the establishment of enrichment cultures in which solid organic phases were used. They also reported that different phenanthrene-utilizing bacteria inhabiting the same soils may be adapted to different phenanthrene bioavailabilities. In addition, the authors showed that the range of phenanthrene bioavailabilities obtained using solid phases with different sorptive properties provides a useful approach for determining the effects of contaminant sorption on microbial selection and for cultivating and characterizing microorganisms that may have more relevance in natural environments. Due to the reduced bioavailability that characterizes chronically hydrocarbons contaminated soils, the bioaugmentation with cultures obtained by enrichment in solid phase systems, could be a promissing strategy to apply in aged contaminated soils. In this context, the objective of this work was to study four bacterial component obtained from a degrader phenanthrene consortium by using solid phases with a resin XAD2 preloaded with phenanthrene, and to rebuild a defined degrading consortium from them. The isolated strains were identified by 16S rRNA and phenotypically characterized using the conventional assays. Furthermore, their main phenotypic features and biochemical characteristics where analyzed by Fourier-transform infrared spectroscopy (FT-IR). The phenanthrene degradation was studied from both in the strain pure cultures and from the defined consortium. Our results showed that the application of XAD2 preloaded with phenanthrene culture systems represents a selective environment towards substrate colonizing bacterial species and allow us study the different strategies to enhance the PAH uptake and allow the bacterial survival in oligotrophic conditions.