Plasmids from environmental strains isolated from High Altitude Lakes

KURTH, D; ORDOÑEZ, OF; FARIAS, ME

Córdoba

Congreso; XI Congreso Argentino de Microbiologia General SAMIGE; 2015

SAMIGE

p { margin-bottom: 0.1in; direction: ltr; line-height: 120%; text-align: left; }High-altitude Andean Lakes (HAAL) are pristine environments with extreme conditions such as high UV radiation, high heavy metal content (mainly arsenic),high salinity, and oligotrophy. Survival in these conditions depends on resistance mechanisms that might be encoded either in genomes or mobile elements. Several linear plasmids have previously been found in actinomycete strains, and a number of genes have been proposed to function as resistance mechanisms. In this work, we searched for plasmids in other HAAL strains. We analysed isolates identified as Exiguobacterium, Acinetobacter or Pseudomonas, as they were among the most abundant within the HAAL collection.Using standard plasmid extraction protocols for Gram(+) and Gram(-) bacteria, small plasmids were isolated from two highly UV-B resistant strains, namely Acinetobacter sp. Ver3 and Exiguobacterium sp. S17. For the Exiguobacterium plasmid, a partial sequence was obtained from the draft genome, and completed and confirmed using PCR. For the Acinetobacter plasmids, restriction fragments were cloned and sequenced, and comparison with the draft genome allowed identifying a full 10kbplasmid and at least one more megaplasmid.Using a different methodology, namely PFGE, it could be further assessed that the Exiguobacterium strain has in fact two more megaplasmids which were not purified with the standard extraction protocol. The sequence of the isolated megaplasmids was also determined from restriction analysis,sequencing and comparison to the draft genome. Some of the genes might be important for survival in the environmental extreme conditions.We present here the sequences obtained and aim to characterize the roleof these mobile genetic elements, both in survival to extreme conditions and in putative transfer of this information to the HAAL microbial community. Characterization of these genetic elements could also help to develop tools for the poorly studied Exiguobacterium genus.