Antibiotic activities of a pseudomonas aeruginosa supernatant

LEOPOLDO OROSCO; CONRADO ADLER; PAULA A. VINCENT

Carlos Paz, Córdoba.

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología molecular; 2008

An antibiotic producing strain was isolated from a human sample. Genus and speciation determination were carried out by 16S rDNA and gyrB sequencing and subsequent analysis of the sequences using BLAST. The strain was identified as Pseudomonas aeruginosa. The supernatant showed activity against different human and plant pathogens. The antimicrobial substance diffused through a dialysis membrane with a 12kDa cut off. The antibiotic activity in the supernatant was resistant to all proteases tested. Thermal sensitivity was also tested by exposing the culture supernatant to 121ºC for 30 minutes resulting in a partial activity decrease.  When the supernatant was adsorbed on a C8 cartridge two different fractions, with antibiotic activity, were eluted at methanol/water (40: 60) and methanol/water (80: 20). The two fractions show dissimilar action spectra. The 40% fraction was susceptible to high temperature whereas the 80% fraction was totality resistant. These last results indicated that the supernatant of this strain contains at lest two different antibiotics. An E. coli strain mutant in tolC gene was hiper-susceptible to the two fractions suggesting a possible role of TolC protein in the exportation of these antibiotics. Identification and characterization of this compound produced by Pseudomonas aeruginosa may represent a novel antibiotic discovery.