Microbe(s): Pseudomonas spp.
In the present study, we evaluated the antimicrobial activity of neutral electrolyzed water (NEW) against 14 strains of spoilage Pseudomonas of fresh cut vegetables under cold storage. The NEW, produced from solutions of potassium and sodium chloride, and sodium bicarbonate developed up to 4000 mg/L of free chlorine, depending on the salt and relative concentration used. The antimicrobial effect of the NEW was evaluated against different bacterial strains at 105 cells/ml, with different combinations of free chlorine concentration/contact time; all concentrations above 100 mg/L, regardless of the salt used, were found to be bactericidal already after 2 min. When catalogna chicory and lettuce leaves were dipped for 5 min in diluted NEW, microbial loads of mesophilic bacteria and Enterobacteriaceae were reduced on average of 1.7 log cfu/g. In addition, when lettuce leaves were dipped in a cellular suspension of the spoiler Pseudomonas chicorii I3C strain, diluted NEW was able to reduce Pseudomonas population of about 1.0 log cfu/g. Thanks to its high antimicrobial activity against spoilage microorganisms, and low cost of operation, the application of cycles of electrolysis to the washing water looks as an effective tool in controlling fresh cut vegetable microbial spoilage contamination occurring during washing steps.
Microbe(s): Penicillium digitatum, Pseudomonas spp.
The efficacy of thin-film diamond coated electrodes (DiaCell 101) for disinfection of water artificially contaminated with Penicillium digitatum and Pseudomonas spp. was tested. Electrolysis process was performed with different operation conditions: current densities at 4, 8, and 12A and water flow rate at 150, 300, and 600 L/h. For both pathogens, the experiments were performed in water suspensions at a final concentration of 105 CFU/ml. Tap water was used as a control. The results showed that fungal spores and bacterial cells were affected by flow rate and current density applied. The higher the water flow rate the greater the inactivation of the two microorganisms which were completely suppressed at high recirculation flow (300-600 L/h/cell). Pseudomonas spp. cells were inactivated at the highest current density applied (8-12A) after 6 min of electrolysis, whereas for P. digitatum the complete inactivation was observed at the same current densities after 12 min. The results obtained suggest that the two parameters can be modulated in order to achieve significant suppression in relation to the target microorganism and to obtain an antimicrobial effect without generation of chlorine.
Microbe(s): Pseudomonas aeruginosa
Weakly acidic hypochlorous acid (HClO 200 ppm, pH 6.5) is effective against a broad range of microorganisms. We have previously reported a study of developing antimicrobial biomaterials made up of chitin-nanofiber sheet (CNFS) -immobilized silver nanoparticles (CNFS/Ag NPs) and showed that either cleansing with HClO or covering with CNFS/Ag NPs daily for more than 7 days resulted in delayed wound healing. This study aimed to evaluate disinfection and wound healing by a combination of cleansing with HClO and covering with CNFS/Ag NPs daily for 3 days. Applying HClO CNFS/Ag NPs daily for 3 days and then cleansing with just pure water and covering with CNFS alone daily for 9 days were performed for Pseudomonas aeruginosa-infected wounds in db/db diabetic mice. We found a significant enhancement of wound healing and a reduction of bacteria counts compared to the controls. Histological examination showed significantly advanced granulation tissue and capillary formations in the wounds on Day 12. These results suggest that limited disinfection to 3 days with HClO CNFS/Ag NPs may be sufficient to avoid negative effects on wound repair.