Analysis of Bacterial Communities from Seawater and Marine Invertebrates from the Beagle Channel by DGGE.

GOMEZ F; LOVRICH G; DELGADO O D; SIÑERIZ F

Orlando, USA

Congreso; 106 General Meeting of the ASM; 2006

Amercian Society for Microbiology, ASM

Background: The Sea is regarded as the origin of life on Earth and the oceans include the largest habitats on Earth hosting the most ancient forms of life. Sub-Antarctic marine ecosystems are an important and poorly studied source of psychrophylic and psychrotolerant microorganisms. Denaturing Gradient Gel Electrophoresis (DGGE) is a technique that allows assessing the structure and genetic diversity of microbial populations. Methods: Seasonal samples were aseptically collected at six sites from Beagle Channel, Southern Argentina. Seawater samples were filtered trough a 0.2 µm filters. Different culture media and conditions were assayed in order to get cultivable microorganisms. Total DNA was extracted from seawater and from the guts of Nacella (Patinigeria) Deaurata and N. (P) magellanica, Loxechinus albus, Pseudoechinus magallanicus, Munida subrugosa, M. gregaria, Paralomis granulosa and Lithodes santolla. Total DNA from cultures was also studied and compared. DNA fragments obtained by PCR were separated in denaturing gradient polyacrylamide gels (DGGE). Results: More UFCml were obtained when the cultures were incubated at 20°C than at 4 or 8°C. Microbial DGGE banding patterns were different in each sample. The presence of multiple bands demonstrated community’s variations among seawater samples and also some seasonal bacterial population differences. There were some common dominant bands present at more than one sampling site. The occurrence of bands of environmental samples suggests the presence of non-culturable microorganisms in the population when compared with amplified fragments from enrichment cultures. Conclusion: The isolates from Beagle Channel, Southern Argentina were predominantly psychrotolerant. The DGGE profile demonstrated that the bacterial community changed along the year. Predominant common bands, single bands, will be excised; purified, re-amplified and sequenced in order to get bacterial identification.