Polycyclic aromatic hydrocarbons degradation by a defined consortia of indigenous bacterial strains

MARTINEZ, FABIANA; BOURGUIGNON, NATALIA; ISAAC, PAULA; FERRERO, MARCELA A.

Rosario de Santa Fé

Congreso; IX Congreso Argentino de Microbiologia General organizado por la Sociedad Argentina de Microbiología General (SAMIGE); 2013

Asociación Argentina de Microbiología

A wide variety of Polycyclic Aromatic Hydrocarbons (PAHs) can be found in the environment by natural or anthropogenic sources. PAHs are known to be dangerous to living organisms and to the environment because of its carcinogenic and toxic properties. Many microorganisms are capable of degrading PAHs and in many cases, a group of them work together to increase its individual catabolic capabilities. In this work, we studied a group of bacteria isolated from PAHs polluted sediment. After characterizing each isolate, we were able to select those with the best degrading properties to conform a mixed culture that could degrade more efficiently a mixture of PAHs. Ten bacteria strains were assayed. Three of them were previously isolated from oil contaminated sediment using a PAHs-enrichment technique. These strains were identified as Pseudomonas monteilii P26, Pseudomonas xanthomarina N12 and Pseudomonas stutzeri N3 and were capable of degrade naphthalene and phenanthrene in culture medium. Seven Gram positive isolates from Patagonian contaminated sites were also studied. All these isolates were actinobacteria, three of them were identified as Rhodococcus genus (P18, F27 and HT33N), another three as Arthrobacter genus (P7, HT33A and HT33B) and only one isolate (H19) was close to Gordonia genus. Each strain was characterized according to their catabolic capabilities, bioemulsifier production and antagonism tests. Screening for naphthalene, phenanthrene and pyrene degradation showed that Pseudomonas strains N3 and P26 degraded more efficiently naphthalene and phenanthrene, while actinobacteria showed the highest percentages of pyrene degradation. These Pseudomonas strains were also selected for their improved bioemulsifier production. We also evaluated potential antagonism effect among the selected strains in solid medium by considering all combinations. According to their capabilities of PAH degradation, bioemulsifier production and non antagonistic effects N3, F27, H19, P26 and P18 strains were combined in order to evaluate sixteen different bacterial consortia for degradation assays of a mixture of naphthalene, phenantrene and pyrene. Finally, a notable improving of the individual efficience was observed with some consortium, specially for the pyrene degradation. Two consortia amounted to double the percentage of removal of this PAH compared with individual results