Improved PAHs removal performance by a defined bacterial consortium of indigenous Pseudomonas and actinobacteria from Patagonia, Argentina

Abstract

Defined mixed cultures consisting of Pseudomonas and actinobacteria strains showed interesting polycyclic aromatic hydrocarbons (PAHs) removal values, improving greatly removal efficiency of strains in pure culture. These bacterial mixed cultures were synthesized with bacteria isolated from contaminated sites, previously evaluated regarding of naphthalene, phenantrene and pyrene removal when operating at flask scale. The results had shown that monocultures of Pseudomonas monteilii P26 and Pseudomonas sp. N3 could degrade efficiently low molecular weight (LMW) PAHs but they did not show interesting high molecular weight (HMW) PAHs removal capabilities. On the other hand, the actinobacteria Rhodococcus sp. P18, Gordonia sp. H19 and Rhodococcus sp. F27 were able to degrade relatively efficiently HMW PAHs but they did not remove LMW PAHs from culture medium. The combination of four of these five strains (called C15 mixed culture) removed 100 % of naphthalene and phenanthrene, and showed the highest pyrene biodegradation activity with removal values close to 42 %, almost 6-times higher than those values recorded with the strains in pure culture. In addition, this defined mixed culture showed also bioemulsifying activities in presence of the tested hydrocarbons, which notably helps to solubilize them during the biodegradation process. We could confirm that highest pyrene degradation rate was observed when bioemulsifying activity was maximum in the mixed culture. Our results reveal that defined mixed culture C15 presents sinergistic activity for effective removal of a mix of PAHs, improving the biodegradation process in a valuable approach.