Antibiotic activity of a Bacillus amyloliquefaciens supernatant against Xanthomonas sp

ADLER CONRADO; VINCENT PAULA

Mar del Plata

Congreso; 43º Scientific Meeting of the Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2007

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Antibiotic activity of a Bacillus amyloliquefaciens supernatant against Xanthomonas sp Using a screenig method to find new antibiotics, a bacterial strain producing an antagonistic compound against Xanthomonas sp. was isolated from a water 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 Bacillus amyloliquefaciens. The antibiotic produced by this strain showed activity against different field isolates of Xanthomonas axonopodis pv. citri (citrus canker agent) and Xanthomonas campestris pv. campestris (black rot agent). This activity was measured by the agar-disk diffusion assay. The antimicrobial substance diffused through a dialysis membrane with a 12kDa cut off and maximum activity was observed at stationary growth phase. Release of this substance was enhanced in a minimal medium compared with a rich medium. The antibiotic was resistant to all proteases tested (trypsin, chemotrypsin and proteinase K). Thermal sensitivity was also tested by exposing the culture supernatant to temperatures of 121ºC for 30 minutes resulting in a partial antimicrobial activity decrease. The compound showed stability when was exposed to extreme pHs (3-11). Identification and characterization of this compound produced by B. amyloliquefaciens may represent a novel antibiotic with potential application in biological control of pathogenic microorganisms.