Optimización de las condiciones de electroporación y agregado de nisina en la inhibición de Pseudomonas aeruginosa / [Optimization of the conditions for electroporation and the addition nisin for Pseudomonas aeruginosa inhibition]

ABSTRACT

A mathematical approach was applied in order to optimize the effect of electroporation by application of pulsed electric fields (PEF) and nisin addition on the inhibition of a strain of Pseudomonas aeruginosa isolated from river sediments. This strain showed to be highly resistant to nisin as only two log cycles reduction of viable cells were obtained in the presence of 84,000 IU/ml nisin. But when a combination of bacteriocin and selected PEF treatment conditions were applied, 4.4-decimal log cycle reduction could be achieved. PEF and nisin interaction seems to be complex, as at lower electric field intensities (i.e., 5 kV/cm) an increment in the number of pulses applied clearly induced a lower inhibitory effect of nisin. At higher PEF intensities (i.e., 11 kV/cm), the inhibitory effect of nisin increased with the number of pulses applied. Results overall, the obtained indicate the possibility of combining PEF and nisin treatments in order to improve the inhibition of resistant microorganisms. The Doehlert experimental design and surface response methodology was an interesting tool to obtain or predict the optimal combination of the stress factors applied.