Diversity of polycyclic aromatic hydrocarbons-degrading bacteria in intertidial marine sediments of patagonia

RIVA MERCADAL, JP; LOZADA, M; DIONISI, HM; SIÑERIZ F; FERRERO MA

Dalian, China

Simposio; 13th International Biotechnology Symposium & Exhibition (IBS-2008); 2008

Dalian Institute of Chemical Physics, CAS

Seven different intertidal marine sediments along patagonian coast of Argentina were analyzed on their intrinsic capability of degrading polycyclic aromatic hydrocarbons (PAHs). Enrichment cultures were set up for 15 days in minimal medium supplemented with naphthalene or phenantrene as a sole carbon and energy source using coastal sediment as inoculum. Total DNA of each naphthalene or phenantrene-enriched bacterial population was extracted. All of the 14 samples were analyzed by a combination of PCR-DGGE. Nearly two hundred bands were reamplified and sequenced in orden to determine the phylogenetic status of the populations. Approximately 25% of bands recovered resulted in operational taxonomic units (OTUs) with 100% identity to Cycloclasticus sp., a versatile PAH-degrading bacterium not reported at these coasts, and 10% showed high identity with Shewanella sp. Other OTUs were related to Vibrio, Pseudoalteromonas, Pseudomonas and Rhodobacter. DNA samples were also used as template for amplification of partial PAH dioxygenase iron sulfur protein (ISP) genes. Primers cyc-p 372f and cyc-p 854r [1], and primers nahAc 149F and nahAc 1014R [2] designed with GC clamp for DGGE were used for these assays. The presence of phnA1-like genes of Cycloclasticus was observed in five of seven sediments analyzed and nah-like genes of Pseudomonas or Sphingomonas in the others. Only one band was obtained of nah-like gene, but several bands were observed at bacterial populations amplified for phnA1-like genes. Amplification products identified as nah-like genes reveal the potential intrinsic capability of degrading PAHs, nevertheless, presence of important amount of OTUs related to the genus Cycloclasticus and their characteristic type phnA1 gene suggests that it could play an important role in the marine degradation of PAHs as it was demonstrated by studies in several sites of the northern hemisphere [3]. References [1] Lozada, M., Riva Mercadal, J.P., Guerrero L.D., Di Marzio, W.D., Ferrero, M.A., and Dionisi, H.M. 2008. Novel aromatic ring-hydroxylating dioxygenase genes from coastal marine sediments of Patagonia. BMC Microbiology. 8:50 [2] Ferrero, M., Llobet-Brossa, E., Lalucat, J., Garcia-Valdes, E., Rossello-Mora, R., Bosch, R.  2002. Coexistence of two distinct copies of naphthalene degradation genes in Pseudomonas strains isolated from the western Mediterranean region. Appl Environ Microbiol.  68:957-962. [3] Kasai, Y., Kishira, H., and Harayama, S. 2002. Bacteria belonging to the genus Cycloclasticus play a primary role in the degradation