Assigning ecological roles to the populations belonging to a phenanthrene-degrading bacterial consortium using omic approaches

FESTA, SABRINA; COPPOTELLI, BIBIANA MARINA; MADUEÑO, LAURA; LOVISO, CLAUDIA LORENA; MACCHI, MARIANELA; NEME TAUIL, RICARDO MARTIN; VALACCO, MARÍA PÍA; MORELLI, IRMA SUSANA

PLOS ONE

PUBLIC LIBRARY SCIENCE

Año: 2017 vol. 12

1932-6203

The present study describes the behavior of a natural phenanthrene-degrading consortium(CON), a synthetic consortium (constructed with isolated strains from CON) and an isolatedstrain form CON (Sphingobium sp. AM) in phenanthrene cultures to understand the interactionsamong the microorganisms present in the natural consortium during phenanthrenedegradation as a sole carbon and energy source in liquid cultures. In the contaminant degradationassay, the defined consortium not only achieved a major phenanthrene degradationpercentage (> 95%) but also showed a more efficient elimination of the intermediate metabolite.The opposite behavior occurred in the CON culture where the lowest phenanthrenedegradation and the highest HNA accumulation were observed, which suggests the presenceof positive and also negative interaction in CON. To consider the uncultured bacteriapresent in CON, a metagenomic library was constructed with total CON DNA. One of theresulting scaffolds (S1P3) was affiliated with the Betaproteobacteria class and resulted in asignificant similarity with a genome fragment from Burkholderia sp. HB1 chromosome 1. Acomplete gene cluster, which is related to one of the lower pathways (meta-cleavage of catechol)involved in PAH degradation (ORF 31±43), mobile genetic elements and associatedproteins, was found. These results suggest the presence of at least one other microorganismin CON besides Sphingobium sp. AM, which is capable of degrading PAH through themeta-cleavage pathway. Burkholderiales order was further found, along with Sphingomonadalesorder, by a metaproteomic approach, which indicated that both orders were metabolicallyactive in CON. Our results show the presence of negative interactions betweenbacterial populations found in a natural consortium selected by enrichment techniques;moreover, the synthetic syntrophic processing chain with only one microorganism with thecapability of degrading phenanthrene was more efficient in contaminant and intermediatemetabolite degradation than a generalist strain (Sphingobium sp. AM).