Peroxygen disinfection ofpseudomonas aeruginosabiofilms on stainless steel discs

Abstract

The disinfection of Pseudomonas aeruginosa biofilms on stainless steel (AISI 304) by a formulation of peracetic acid and hydrogen peroxide [Proxitane ® 5] has been studied using a laboratory scale rig incorporating a modified Robbins device. The influence of disinfectant temperature, flow rate and concentration has been characterised and comparisons made between biofilms established under static and nutrient flow conditions. Disinfection was enhanced with increased concentration of disinfectant (1-25 ppm peracetic acid, PAA) at all flow rates tested. The greatest reduction in viable cell number occurred at the highest temperature tested (50°C). At 30°C, the transition from laminar to turbulent flow (at 0.768 ms -1 ) was accompanied by a 99.7% increase in disinfection at 15 ppm PAA. This effect was not attributable to dislodgement of cells by increased fluid mechanical shear alone. Increased flow velocity (0 to 0.993 m s -1 ) and moderate (10°C) increments in temperature enhanced disinfection effectiveness in the Proxitane ® 5 concentration range corresponding to 5 ppm PAA to 25 ppm PAA. An insight into biofilm disinfection has been gained and the results are relevant to industrial Clean-in-Place processes.

Response of Bacterial Biofilms in Recirculating Aquaculture Systems to Various Sanitizers

“…Chlorine sanitizers are also broad-spectrum germicides (Cords and Dychdala 1993;Boothe 1998), which represent the majority of significant pathogens of the aquaculture industry. Both PAA and sodium hypochlorite act on microorganisms by denaturing proteins in the cell walls, leading to alteration of the chemiosmotic function of the cell membrane and oxidation of the enzymes, leading to impairment of cellular biochemical pathways (Cords and Dychdala 1993;Blanchard et al 1998;Boothe 1998).…”

Application of Fluid Dynamic Gauging in the Characterization and Removal of Biofouling Deposits

“…Biofouling is no exception. The problem is most notable in the food industry, where biofilms can grow on all surfaces that are vulnerable to local bacteria inhabitation, such as pipe bends, conveyor belts, floors and rubber seals (Blanchard et al [1]). As well as the process equipment, microbes can also thrive on ceilings (as a result of condensation), guttersand drains of food processing facilities.…”

“…For some disinfectants, the concentration must be increased by between 10 and 100 times in order to achieve the same level of deactivation of biofilm-based bacteria compared with their planktonic equivalents (Blanchard et al [1]). This is partly due to the EPS, which is important for attachment and resistance to natural shear forces, and also owes much to the physiological adaptation to existence within a biofilm (sessile growth, nutrient stresses, continuous contact with low levels of disinfectant) (Bridier et al [7]).…”

Measuring Antimicrobial Efficacy against Biofilms: a Meta-analysis

“…The two studies have internally consistent dose-response behaviors; they differ dramatically, however, in their quantitative determinations of efficacy. To achieve a 3-log-unit reduction, the study by Blanchard et al (21) indicates an exposure of 16.5 mg · min/liter, whereas an exposure of 84,000 mg · min/liter is suggested by the data of Spoering and Lewis (22), which is a 5,000-fold difference (3 orders of magnitude).…”

“…Predictors influencing outcomes of antimicrobial biofilm tests. We can gain some insight into the method features that are most important by briefly digressing to consider the methodological differences between the systems used by Blanchard et al (21) and by Spoering and Lewis (22). Again, these studies both investigated the effects of peracetic acid on P. aeruginosa biofilms but arrived at quite different results.…”