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

ARNAU VG; SANCHEZ LA; DANILOVICH M; FARIÑA JI; DELGADO OD

Cordoba

Congreso; XI Congreso Argetino de Microbiologa General; 2015

Sociedad Argentina de Microbiologia General

The increasingresistance of pathogens to common antibiotics currently used has encouraged thesearch for novel antimicrobials. On the other hand, environmental healthconcern has also led to the search of natural biocontrol agents for replacingor decreasing the use of agrochemicals. Microorganisms represent a valuable andfrequently unexplored natural source of bioactive metabolites. In thisscenario, bioprospecting programs involving pristine environments constitute aninteresting alternative for discovering and developing novel bioactive compounds.Pseudomonas spp. exhibits a high metabolic diversity and many specieshave been reported as biocontrol agents, being able to produce a wide spectrumof useful biomolecules such as antibiotics, siderophores, volatiles,biosurfactants, among others. The aim of this work was to provide firstinsights about the antagonistic activity from P. yamanorum 8H1T,a strain isolated from Isla de los Estados, Ushuaia. Antimicrobial activityproduction (expressed as AU mL-1) was evaluated in different culturemedia: SNB, LB, Kings B, R2A, CSM, M9 and M63 by using the critical dilutionmethod. Effect of temperature and pH on antimicrobial production, siderophoreactivity and biosurfactant production was simultaneously evaluated. Treatmentswith catalase, lipase, a-amylase and different proteases aided at elucidatingthe biochemical nature of the antimicrobial produced. Antimicrobial net chargewas determined by inhibition-zone movement after electrophoresis on agarosegel. Purification of the compound was attempted by reversed-phase SPE, followedby RP-HPLC coupled to a PDA detector. P. yamanorum 8H1Tantimicrobialactivity was assessed against both, enteropathogenic and phytopathogenicmicroorganisms, showing a broad inhibitory spectrum against bacteria relevantfor health, as well as for the agricultural and food industry; although inhibitionof phytopathogenic fungi was not observed. Maximum inhibitory activity wasobtained in CSM medium at 20°C, showing that bacterial antagonism was neitherrelated to siderophore- nor biosurfactant-like compounds, although bothactivities were detected for living-cell and cell-free supernatants. The antimicrobialshowed similar properties, such as positive net charge, resistance to proteasesand the UV-Vis spectrum, to those of pseudobactin, a well-known siderophoreproduced by species of P. fluorescens,.However, the non-siderophorenature of the produced antimicrobial makes difficult to relate it withpseudobactin. Further studies including HPLC-MS/MS and NMR are expected to helpat elucidating the P. yamanorum 8H1T antimicrobial structureand its potential novelty.