Applications of nisin for biofouling mitigation of reverse osmosis membranes

This study addresses the potential of application of nisin, a polycyclic antimicrobial peptide produced by Lactococcus lactis, as a novel biological agent for control/mitigation of biofilms formed by three different microorganisms: (i) Pseudomonas aeruginosa P60, (ii) Bacillus species, and (iii) a mixed culture of the two species. Nisin did not affect the growth rate of either strain, while the viability of Bacillus sp. was decreased, as compared to P. aeruginosa P60. Nisin was particularly effective for the dislodging of bacterial cells and extracellular polymeric substances (EPS) for P. aeruginosa P60. Water permeability of biofouled membranes was recovered by over 92% for all the bacterial strains investigated after nisin cleaning in a dead-end filtration system. Nisin has no detrimental effect on RO membrane and thus, has a potential as a biological agent for the mitigation of membrane biofouling.