Sunday, July 24, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
Streptomyces is a genus with biotechnological importance due to its capacity to produce industrially important secondary metabolites (antibiotics, antitumoral compounds, immunosuppressive agents, etc.). In our laboratory we isolated a strain from soil and denominated it K-155. 16S DNA amplification and the presence of diaminopimelic acid in the cell wall revealed that it belongs to the Streptomyces genus, closely related to Streptomyces thermocarboxydus and Streptomyces aureus. However, a polyphasic taxonomic study showed differences with those strains in pigment production, halotolerance and carbon source assimilation. For this reason, we propose that this strain is a novel species, although this status has not been assigned. During its characterization, antibiotic activity against Gram-positive bacteria and yeast was detected, leading us to perform experiments in order to purify the compound and elucidate its structure. Among different culture media tested, YMG medium (Yeast Extract, Malt Extract and Glucose) was the best for antibiotic production. Fermentations were carried out for 6 days on a rotary shaker (29°C, 180 rpm). Several solvents were tested for antibiotic extraction from the culture media to allow further purification. Methanol was the best solvent for this purpose. Since this alcohol precipitates proteins, we can infer the antibiotic is not of a proteic nature. The crude extract was separated using a preparative TLC in a mobile phase of hexane: acetone: water (1:3:1), the fractions that conserved antibiotic activity had an Rf of 0.18 and 0.15. These fractions will be purified by HPLC for further analysis by MS, IR and NMR for structure determination.