Role of the polymeric matrix constituents on the performance of a biocide against pseudomonas fluorescens biofilms

The effectiveness of glutaraldehyde – a very common biocide – to control biofilms formed by Pseudomonas fluorescens on stainless steel slides, was investigated. The tests were performed using two concentrations of the biocide (50 and 100 mg Lˉ¹), biofilms of two ages (7 and 15 days), several pH values (5, 7 and 9) and a range of exposure times (from 0 to 1, 3, 7 and 24 hours). The GTA action on biofilm and planktonic populations was assessed by means of activity tests and wet weight of the biofilms. The results showed that biofilms were not completely removed after the treatment with biocide, in all the situations studied. The higher concentration was more effective in reducing the bacterial activity of the biofilm. The biocide proved to be more effective for longer exposure times. GTA showed good antimicrobial activity against P. fluorescens in suspension, with higher activity for pH 9. The findings of this study suggest that when GTA is used to control biofilms, it reacts with one of the components of the matrix – the proteins – thereby reducing its antimicrobial action.Instituto de Biotecnologia e Química Fina (IBQF)