Synergy of sodium dodecyl sulfate and citric acid in removing bacterial biofilms in hydroponic farming facilities

This research explored various concentrations of sodium dodecyl sulfate (SDS) and citric acid (CA), both individually and in combination, to assess their effectiveness against Salmonella biofilms in hydroponic agriculture systems. Results demonstrated that a combined sanitizer of 0.1% SDS (1.0 ± 0.1 log reduction when used alone) and 1% CA (1.4 ± 0.3 log reduction when used alone) was highly effective in eliminating Salmonella biofilms from PVC pipes in hydroponic systems, reducing biofilm levels to below detectable limits (> 5.6 log reduction when used in combination). Confocal laser scanning microscopy (CLSM) showed significantly greater proportions of damaged/dead cells in the 0.1% SDS- and 1% CA-treated samples (82.6 ± 2.6%) than in the single treatment with 0.1% SDS (26.1 ± 3.0%) and 1% CA (31.6 ± 2.5%) (P < 0.05). Fourier transform infrared (FTIR) spectroscopy together with analysis of proteins and polysaccharides in the extracellular polymeric substances (EPS) of the biofilm matrices showed that the treatment not only affected bacterial viability but also significantly reduced the biomass of the biofilm. In summary, this research provides a foundation for the development of improved cleaning protocols in hydroponic systems, promoting safer and more sustainable farming practices.