PLASMIDS FROM ENVIRONMENTAL STRAINS ISOLATED FROM HIGH ALTITUDE ANDEAN LAKES

DANIEL KURTH,; OMAR F. ORDOÑEZ; M. E. FARÍAS

Cordoba

Congreso; XI Congreso Argentino de Microbiología General (SAMIGE).; 2015

SAMIGE

High-altitudeAndean Lakes (HAAL) are pristine environments with extreme conditionssuch as high UV radiation, high heavy metal content (mainly arsenic),high salinity, and oligotrophy. Survival in these conditions dependson resistance mechanisms that might be encoded either in genomes ormobile elements. Several linear plasmids have previously been foundin actinomycete strains, and a number of genes have been proposed tofunction as resistance mechanisms. Inthis work, we searched for plasmids in other HAAL strains. Weanalysed isolates identified as Exiguobacterium,Acinetobacteror 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 resistantstrains, namely Acinetobactersp. Ver3 and Exiguobacteriumsp. S17. For the Exiguobacteriumplasmid, a partial sequence was obtained from the draft genome, andcompleted and confirmed using PCR. For the Acinetobacterplasmids, restriction fragments were cloned and sequenced, andcomparison with the draft genome allowed identifying a full 10kbplasmid and at least one more megaplasmid.Usinga different methodology, namely PFGE, it could be further assessedthat the Exiguobacteriumstrain has in fact two more megaplasmids which were not purified withthe standard extraction protocol. The sequence of the isolatedmegaplasmids was also determined from restriction analysis,sequencing and comparison to the draft genome. Some of the genesmight be important for survival in the environmental extremeconditions.Wepresent here the sequences obtained and aim to characterize the roleof these mobile genetic elements, both in survival to extremeconditions and in putative transfer of this information to the HAALmicrobial community. Characterizationof these genetic elements could also help to develop tools for thepoorly studied Exiguobacteriumgenus.