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

ARNAU GV; DANILOVICH ME; SÁNCHEZ LA; FARIÑA JI; DELGADO OD

Córdoba

Congreso; XI Congreso Argentino de Microbiología General SAMIGE; 2015

SAMIGE

The increasing resistance of pathogens to common antibiotics currently used has encouraged the search for novel antimicrobials. On the other hand, environmental health concern has also led to the search of natural biocontrol agents for replacing or decreasing the use of agrochemicals. Microorganisms represent a valuable and frequently unexplored natural source of bioactive metabolites. In this scenario, bioprospecting programs involving pristine environments constitute an interesting alternative for discovering and developing novel bioactive compounds. Pseudomonas spp. exhibits a high metabolic diversity and many species have been reported as biocontrol agents, being able to produce a wide spectrum of useful biomolecules such as antibiotics, siderophores, volatiles, biosurfactants, among others. The aim ofthis work was to provide first insights about the antagonistic activity from P. yamanorum 8H1^T, a strain isolated from Patagonia (Argentina). Antimicrobial activity production (expressed as AU mL-1) was evaluated in different culture media: SNB, LB, King's B, R2A, CSM, M9 and M63 by using the critical dilution method. Effect of temperature and pH on antimicrobial production, siderophore activity and biosurfactant production was simultaneously evaluated. Treatments with catalase, lipase, alpha-amylase and different proteases aided at elucidating the biochemical nature of the antimicrobial produced. Antimicrobial net charge was determined by inhibition-zone movement after electrophoresis on agarose gel. Purification of the compound was attempted by reversed-phase SPE, followed by RP-HPLC coupled to a PDA detector. P. yamanorum 8H1^T antimicrobial activity was assessed against both, enteropathogenic and phytopathogenic microorganisms, showing a broad inhibitory spectrum against bacteria relevant for health, as well as for the agricultural and food industry; although inhibition of phytopathogenic fungi was not observed. Maximum inhibitory activity was obtained in CSM medium at 20°C, showing that bacterial antagonism was neither related to siderophore- nor biosurfactant-like compounds, although both activities were detected for living-cell and cell-free supernatants. The antimicrobial showed similar properties, such as positive net charge, resistance to proteases and the UV-Vis spectrum, to those of pseudobactin, a well-known siderophore produced by P. fluorescens. However, the non-siderophore nature of the produced antimicrobial makes difficult to relate it with pseudobactin. Further studies including HPLC-MS/MS and RMN are expected to help at elucidating the P. yamanorum 8H1^T antimicrobial structure and its potential novelty.