title: Dual activity of pyocyanin from Pseudomonas aeruginosa--antibiotic against phytopathogen and signal molecule for biofilm development by rhizobia.
abstract: The purified pyocyanin from Pseudomonas aeruginosa TO3 was investigated for its antagonistic activity against Macrophomina phaseolina and as a signaling molecule for development of biofilm by rhizobial strain Ca2. The antagonistic activity of purified pyocyanin, as determined by a dry mass method, showed inhibition of M. phaseolina. Biofilm formation by strain Ca2 was performed by crystal violet assay. There was an increase in biofilm development by Ca2 with an increase in pyocyanin concentration up to 0.12 nmol·L(-1), followed by a reduction. Using a well-diffusion method, we determined the effect of pyocyanin on disease suppression and biofilm formation by strain Ca2 on radicles of groundnut ( Arachis hypogaea L. ) placed in three concentric whorls on water agar plates. Pyocyanin suppressed disease better at high concentration; however, at lower concentrations increased colony-forming units of Ca2 on radicles of seedlings was observed. A field study in soil infested with M. phaseolina showed that a coinoculant of P. aeruginosa TO3 and rhizobial strain Ca2 enhanced nodule mass and nitrogenase activity by 264.38% and 269.06%, respectively, over that of the control. This study reports that application of pyocyanin-producing pseudomonads together with rhizobia contributes to the enhancement of nodulation ability and better sustains the growth and productivity of groundnut even in the presence of M. phaseolina.
authors.affiliation: Department of Microbiology, Institute of Biosciences and Biotechnology, Chhatrapati Shahu Ji Maharaj University, Kanpur 208024, UP, India. nkarora_net@rediffmail.com
authors.forename: Ekta
authors.initials: E
authors.lastname: Khare
authors.forename: Naveen Kumar
authors.initials: NK
authors.lastname: Arora
mesh_terms: D000935:Antifungal Agents / Q000378:metabolism / Q000494:pharmacology*; D001203:Ascomycota / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D018517:Plant Roots / Q000254:growth & development / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000378:metabolism*; D011710:Pyocyanine / Q000378:metabolism / Q000494:pharmacology*; D012231:Rhizobium / Q000187:drug effects / Q000254:growth & development; D015398:Signal Transduction
chemical_list: D000935:Antifungal Agents; D011710:Pyocyanine