Aromatic Hydrocarbon Degradation Genes from Chronically Polluted Subantarctic Coastal Marine Sediments

MARCOS, MAGALÍ; LOZADA, MARIANA; DIONISI, HEBE

LETTERS IN APPLIED MICROBIOLOGY

Wiley Interscience

Año: 2009 vol. 49 p. 602 - 608

0266-8254

Cold marine ecosystems are particularly vulnerable to hydrocarbon pollution. The characterization of indigenous hydrocarbon degrading bacterial populations is fundamental for the development of effective bioremediation strategies that adapt to these particular environments. In this work we analyzed the bacterial populations of chronically polluted sediments from Ushuaia Bay, (Argentina), using culture-independent molecular methods. We amplifed genes encoding the large subunit of the catalytic component of aromatic ring-hydroxylating dioxygenase (ARHD), the enzyme involved in the first step of the degradation of aromatic hydrocarbons. Complementing our previous studies, we now targeted sequences specifically related to Gram-positive bacteria.By analyzing 170 clones from two environmental libraries of the same site sampled at different years, we identified 14 distinct groups of ARHD sequences. Most of them showed significant relatedness with ARHDs from Gram-positive bacteria of the genera Rhodococcus, Mycobacterium, Nocardioides, Terrabacter and Bacillus, but the level of identity was low to moderate (35-78% at the amino acid level). However, by distance and phylogenetic analysis, we were able to place most of the sequences in types IV and V ARHDs, according to a recent classification scheme based not only on sequence information but also on interaction between enzyme components. Analysis of indels (insertions-deletions) found in certain sequences supported this classification. This molecular information will be used to design high-throughoutput molecular tools such as qPCR in order to improve the design, implementation and monitoring of bioremediation protocols in cold marine environments.