Bibiana Coppotelli
Center for Research and Development in Industrial Fermentation (CINDEFI) La Plata, Argentina
Title: Effects of bacterial inoculants on soil microbiomes and biodegradation in hydrocarbon contaminated soils
Biography
Biography: Bibiana Coppotelli
Abstract
Over the years, we have collected different bacterial strains belonging to sphingomonadaceae family, which have in common the ability to degrade PAH (polycyclic aromatic hydrocarbons). Their genomes have been fully sequenced (WGS) showing similarities in genes codifying enzymes involved in PAH degradation. All of them showed different degradation kinetics in cultures with phenanthrene as sole carbon source. This differences were confirmed when were inoculated in soil contaminated with phenanthrene. The bioaugmentation of the strain Sphingomonas paucimobilis 20006FA revealed a reduction in genetic and functional diversity of soil, and the accumulation of toxic phenanthrene metabolites reducing efficiency in phenanthrene degradation. This effect was not observed when a similar experiment was performed with Sphingobium sp. AM strain, suggesting that despite coding for the same enzymes the genes of the strains would be regulated differently. The effect of the inoculation with strain 20006FA and Sphingobium sp. 22B (more resistant to C-starvation and drying conditions) on contaminated soil in a desiccation environment, suggests that strain 22B is the most suitable due to its adaptation to the usual environmental conditions. The effect of bioaugmentation with Sphingobium sp. AM strain on different soils microbiomes (chronically and recently contaminated soil) revealed an increase in the richness and diversity (pyrosequencing) in both contaminated microbiomes. An improvement in the elimination of phenanthrene occurred only in recently contaminated soil. In all cases, there was evidence of the establishment of the inoculants, which occurred together with the modification of the microbiome of the soils. It was verified that the establishment of an inoculant in the soil does not necessarily correlate with the increase of the desired catabolic capacities, in our case the degradation of PAH, because it could have been established in function of other resources. We have observed that efficiency of an inoculant in soil is not directly related to its genetic potential but to other physiological properties, which could be translated in a distinctive environmental behavior.