Attacking stressed Pseudomonas protegen biofilms with Wi-Fi
Najmah Abdul Razak
Date of Issue2017-05-25
School of Mechanical and Aerospace Engineering
Pseudomonas protegens (Pf-5) is a plant-based, gram-negative bacteria that can be readily found in various surrounding environments; from the natural-occurring environments to the man-made industrial environments. Inoculums were diluted at an absorbance of 0.05 to obtain measurements of 1×108 CFU/ml at a wavelength of 670 nm. The biofilms of the Pseudomonas protegens were cultured in 96-polystyrene microplates at 25±0.1°C with an agitation of 100 rpm in M9 minimal media at 10 varying concentrations of MgCl2 (0 Mm/L, 0.0145 Mm/L, 0.0291 Mm/L, 0.058 Mm/L, 0.116 Mm/L, 0.23 Mm/L, 0.465 Mm/L, 0.93 Mm/L, 2 Mm/L and 3.72 mM/L). There were two 20-hour cycles of incubation. The first cycle is an incubation period to grow the biofilms under different concentrations of magnesium ions (Mg2+) without the influence of Wi-Fi. The second 20- hour cycle sees the biofilms being subjected to Wi-Fi signals. Control experiments were conducted as well to compare differences between the effects of biofilm formation and behaviour when subjected to Wi-Fi and when not subjected to Wi-Fi. Findings have shown that differences in nutrient concentrations are significant. Higher Mg2+ nutrient availability resulted in higher absorbance measured of the growth of biofilms as compared to lower Mg2+ nutrient availability. There were no significant effects of Wi-Fi on biofilm growth. However, Wi-Fi may have enhanced the formation of biofilms, and results were supported by correlation coefficients obtained. Correlation coefficients were higher when biofilms were subjected to Wi-Fi as compared to those that were not subjected to Wi-Fi.
Final Year Project (FYP)
Nanyang Technological University