Bacterial Attachment and Initiation of Biofilms on the Surface of Copper Containing Stainless Steel

Abstract

Type 304 stainless steel, copper containing stainless steel, and oxygen free copper were subjected to antibacterial tests and short term exposure experiments in a laboratory. Antibacterial tests showed that the copper containing stainless steel, as well as oxygen free copper, was antibacterial, yet the antibacterial activity of the copper containing stainless steel was lower than that of the oxygen free copper. In short term exposure experiments, the copper containing stainless steel, as well as type 304 stainless steel, didn't sterilize planktonic bacterial cells, while the oxygen free copper reduced the number of alive planktonic bacterial cells. The copper containing stainless steel did not protect itself from bacterial adhesion, but sterilized about 75 % of sessile bacterial cells and reduced formation of biofilms on its surface. Such experimental results indicate that the copper containing stainless steel is effective against biofilm related impacts.KEY WORDS: antibacterial stainless steel; copper; bacterial attachment; biofilm; microbiologically influenced corrosion; biocorrosion. 133© 2010 ISIJ spores and vegetative cells, and the functions were not reduced by dissolved organic substances. 26) In this paper, copper was selected as the antibacterial agent because of its higher bactericidal function comparative to silver. 27) Bacterial attachment and initiation of biofilms on a copper containing stainless steel surfaces were studied. Experimental Sample Materials and Preparation of SpecimensSample materials subjected to experiments were type 304 stainless steel (SS), copper containing stainless steel (Cu-SS) (MSSAM3, Nisshin Steel Co., Ltd., Tokyo, Japan) and oxygen free copper (OFC). Copper concentration in the Cu-SS was 3.78 mass%. As the phase of the Cu-SS was austenite, type 304 stainless steel was selected as a reference stainless steel. The chemical compositions of the sample materials are summarized in Table 1.Coupon specimens for antibacterial tests, 25 mmϫ25 mmϫ1 mm, were machined from supplied plates. The surfaces of specimens were polished by #1500 emery papers to obtain uniform surface finish. The polished specimens were subjected to ultrasonic cleaning in 70 % ethanol solution followed by drying and sterilization under ultraviolet (UV) ray illumination in a clean bench. Steam sterilization was not employed for sterilization of specimens because the steam sterilization process could make oxide layer and change chemical properties of the sample metal surfaces.Poly-ethylene (PE) films used in antibacterial tests were cleaned, sterilized and dried in the same manner as those for the specimens.For exposure experiments, coupon specimens with the size of 12.5 mmϫ12.5 mmϫ1 mm were used. Except the size of specimens, the preparation processes of specimens for exposure experiments was the same as that employed for the preparation of the specimens subjected to antibacterial tests. InoculumBacteria used in this study were Pseudomonas sp. The bacteria were isolated from a water system where MIC was suspecte...

Effects of NaOCl Aqueous Solutions and Ethyl Alcohol Solutions on Removing Protein Surface Contaminants and Re-establishing Antibacterial Activities of Copper-Alloyed Stainless Steel

“…General-purpose stainless steel is not antibacterial: pathogens remain viable on stainless steel surfaces and present a contamination hazard for considerable periods of time Dietze et al, 2001;Higashino and Kamiya, 2011;Kramer et al, 2006;Kusumanigrum et al, 2003;Rose et al, 2003;Shams et al 2007 . Alloying with copper gives stainless steel some antibacterial activities, as has been well confirmed by several studies Hong and Koo, 2005;Kawakami et al, 2010;Kielemoes and Verstraete, 2001;Noyce et al, 2006;Suzuki et al, 2001 and 2014 . Introducing antibacterial stainless steel into frequently hand-touched places has been considered to reduce risks of outbreaks of illnesses caused by pathogens via environmental surfaces.…”

Effect of Nano-sized Cu-Rich Phase on Microbiological Corrosion Behavior of Cu and Ni-Added Steel for Oil Country Tubular Goods

“…[27][28][29][30] The antibacterial mechanism was attributed to the "contact killing" of Cu which possesses a high toxicity to bacteria. 26,[31][32][33][34][35] However, the Cu-bearing stainless steels could not well mitigate MIC against SRB. Liu et al 36) claimed that the Cu precipitates on the steel would react with sulfides produced by SRB metabolizing and form the copper sulfide on the steel surface, thus, losing its toxicity to SRB.…”

Attachment and survival of bacteria on apples with the creation of a kinetic mathematical model

“…The following bacterial cultures: E. coli ATCC 25922, S. aureus ATCC 25923, P. aeruginosa ATCC 10145 and B. cereus ATCC 7004 from the collection of the Laboratory of bacteriology, mycology and parasitology of Veterinary Institute of Republic of Srpska "Dr. Vaso Butozan" Banja Luka, Bosnia and Herzegovina, were used. The cultures were grown in a nutrient broth and incubated for 24 h at 37 °C, after which they were inoculated and grown on nutrient agar for the next 24 h [21,22].…”