First insights into the Pseudomonas yamanorum 8H1T antimicrobial activity and its biotechnological potential

ARNAU V.G.; DANILOVICH, M.E; SANCHEZ L. A; FARIÑA J.I; DELGADO O.D.

Córdoba

Congreso; XI Congreso Argentino de Microbiología General; 2015

SAMIGE

Theincreasing resistance of pathogens to common antibiotics currently used hasencouraged the search for novel antimicrobials. On the other hand, environmentalhealth concern has also led to the search of natural biocontrol agents forreplacing or decreasing the use of agrochemicals. Microorganisms represent avaluable and frequently unexplored natural source of bioactive metabolites. Inthis scenario, bioprospecting programs involving pristine environments constitutean interesting alternative for discovering and developing novel bioactivecompounds. Pseudomonas spp. exhibits ahigh metabolic diversity and many species have been reported as biocontrolagents, being able to produce a wide spectrum of useful biomolecules such asantibiotics, siderophores, volatiles, biosurfactants, among others. The aim ofthis work was to provide first insights about the antagonistic activity from P. yamanorum 8H1T, a strainisolated from Isla de los Estados, Ushuaia. Antimicrobial activity production (expressedas AU mL-1) was evaluated in different culture media: SNB, LB, King?sB, R2A, CSM, M9 and M63 by using the critical dilution method. Effect oftemperature and pH on antimicrobial production, siderophore activity andbiosurfactant production was simultaneously evaluated. Treatments withcatalase, lipase, a-amylaseand different proteases aided at elucidating the biochemical nature of theantimicrobial produced. Antimicrobial net charge was determined by inhibition-zonemovement after electrophoresis on agarose gel. Purification of the compound wasattempted by reversed-phase SPE, followed by RP-HPLC coupled to a PDA detector.P. yamanorum 8H1Tantimicrobial activity was assessed against both, enteropathogenic andphytopathogenic microorganisms, showing a broad inhibitory spectrum against bacteriarelevant for health, as well as for the agricultural and food industry; althoughinhibition of phytopathogenic fungi was not observed. Maximum inhibitoryactivity was obtained in CSM medium at 20°C, showing that bacterial antagonismwas neither related to siderophore- nor biosurfactant-like compounds, althoughboth activities were detected for living-cell and cell-free supernatants. Theantimicrobial showed similar properties, such as positive net charge,resistance to proteases and the UV-Vis spectrum, to those of pseudobactin, a well-knownsiderophore produced by species of P. fluorescens,.However, the non-siderophore nature of the produced antimicrobial makesdifficult to relate it with pseudobactin. Further studies including HPLC-MS/MSand NMR are expected to help at elucidating the P. yamanorum 8H1T antimicrobial structure and its potentialnovelty.