CONICET | Buscador de Institutos y Recursos Humanos

The biotechnological microbial potential of twosalterns from La Pampa, Argentina has been explored. Salitral Negro andColorada Grande are neutral hypersaline basins commercially exploded for NaClextraction. Several microorganisms were isolated from water samples and screenedfor hydrolytic activities and bioactive molecules. Pure isolates wereidentified by sequencing a PCR-generated fragment of the 16S rRNA gene. Sevenrepresentatives of Archaea and twofrom Bacteria were obtained and screenedfor the presence of lipolytic and cellulolytic activities, as they areinteresting enzymes for industrial application. Microorganisms were grown on SWagar medium supplemented with olive oil, Tween 20 and Tween 80 as source oftriacylglycerols and esters of lauric or oleic acids. Tweens also allow testingthe enzyme preference for saturated or un-saturated fatty acids. Har. argentinensis, Har. japonica and Salicola sp. degraded all the substrateswhile Har. vallismortis onlyhydrolysed olive oil and the un-saturated fatty acids contained in Tween 80. Thisobservation suggests that the activities detected in Har. argentinensis, Har. japonica, Har. vallismortis and Salicola sp. may be attributed todifferent enzymes (lipase and esterase) or by an extracellular lipaseexhibiting both activities. The activities detected in Hbt. piscisalsi and Hrr.tebenquichense only with both Tweens may correspond to an extracellularesterase since they failed to degrade olive oil.The assay for cellulolyticactivity suggested that Salicola sp.,Har. vallismortis and Hbt. piscisalsi degraded CMC (carboxymethylcellulose). The occurrence of biosurfactants was tested byemulsifying assays using cell-free culture media of the isolates. Olive oil andxylenes were used as substrate and SDS and Triton X-100 as positive controls. Har. japonica, Har. vallismortis, Hbt. piscisalsi and Salicola sp. produced surfactants that emulsified both aromaticcompounds and long chain hydrocarbons whereas those synthesized by S. ruber, Har. argentinensis, Hbt. salinarumand Hrr. tebenquichense or Halobacterium sp. specificallyemulsified long chain hydrocarbons or aromatic compounds respectively.To search for antimicrobial compounds each microorganism was tested against each otherand growth inhibition was analyzed by the presence of halos on agar plates. Bacterialisolates were resistant to the archaeal isolates and vice versa, indicatingthat no inter-domain interaction existed. Har.argentinensis and Har. japonicawere the most effective producers inhibiting growth of most archaeal isolateswhereas Hrr. tebenquichense was themost sensitive strain.These results show thepotential of halophilic microorganisms inhabiting Argentinian salterns,reinforcing the idea of screening extreme environments as a source of potentiallynovel and useful molecules.Supported by CONICET yUNMDP