PAH removal by simultaneous and sequential inoculation of Pseudomonas monteilii P26 and Gordonia sp. H19 in the presence of biostimulants

Abstract

Biostimulation and bioaugmentation have been proposed as sustainable alternatives to physicochemical treatments for the environmental decontamination of polycyclic aromatic hydrocarbons (PAH). PAH-removing Pseudomonas monteilii P26 and Gordonia sp. H19, alone or combined with organic and inorganic biostimulants, were previously proposed as candidates to be included in biotechnological products to be used in eco-friendly decontamination processes. This work aims to study the effect of biostimulants on the growth, cell hydrophobicity and emulsifying activity of P. monteilii P26 and Gordonia sp. H19, and to evaluate the influence of selected biostimulants and bacterial inoculation procedure on PAH bioremoval. A complete factorial experimental design was applied to determine the effect of KNO3, K2HPO4, corn steep liquor (CSL) and a PAH mixture on the growth, cell hydrophobicity and bioemulsifying activity of bacterial cultures. The kinetics of PAH bioremoval was evaluated in simultaneous and sequential cultures of P. monteilii P26 and Gordonia sp. H19 in the presence of selected biostimulants. CSL was the only nutrient that exerted positive effects on all responses evaluated, although these effects were not significant in all cases. In mixed cultures, maximum bioremoval of phenanthrene and pyrene was evidenced when the bacterial strains were simultaneously inoculated, independently of the presence or absence of CSL. These results support the biotechnological characterization of two PAH-removing autochthonous Patagonian strains.