Rapid evaluation of the efficacy of microbial cell removal from fabrics

Abstract

The efficacy of microbial cell removal (EMR) from fabrics is a practically important indicator for the evaluation of cleansers and detergents. EMR is expressed quantitatively by the relative number of viable cells remaining on a fabric swatch after the treatment with these reagents. In order to count the viable cells on the swatch directly and rapidly, we have developed a unique microscopic imaging system with an ultra-deep focusing range. Standard swatches of cotton fabric were inoculated with microorganisms such as Pseudomonas fluorescence, Staphylococcus aureus, or Candida albicans. After the incubation on an agar medium, each swatch was treated with a fluorescent glucose, 2-[N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl) amino]-2-deoxyglucose, to stain only viable cells. The images of every cell distributed within the surface layer with no greater than 130 microm thickness could be integrated into one image. Thus visualized cells could be counted automatically by a novel imaging program. Using a pair of cotton swatches (0.5 x 1.0 cm(2)) inoculated with C. albicans, EMR was evaluated quantitatively. Before washing, the total number of viable cells found on the observation area (3.8 x 10(-4 )cm(2)) was 288 cells. After washing with a test detergent, no cell (<1) was detected. For this case, EMR was given by the formula: log(288/<1)=greater than 2.5. The imaging and cell count of a test fabric could be performed within 1 h.

Transport of a Fluorescent Analogue of Glucose (2-NBDG) versus Radiolabeled Sugars by Rumen Bacteria and Escherichia coli

“…Kinetics of solute transport traditionally have been measured with radiolabeled tracers. , Over the past two decades, transport has also been measured with fluorescently labeled tracers, including analogues of glucose, − other monosaccharides, trehalose, amino acids, , peptides, toluene, and polyamines . Some fluorescent tracers are not labeled analogues but are naturally fluorescent compounds that fortuitously are transported by a transporter system of interest; for example, esculin is transported by type I plant sucrose transporters .…”

Visualization of yeast single-cells on fabric surface with a fluorescent glucose and their isolation for culture

“…The detailed components of the UDF Xuorescent system are described previously [4,5]. Ultra long distance industrial optical lenses (CFI Plan EPI SLWD 50 and 30, NIKON Co., working distance 17.0 and 24.0 mm, respectively) and a semi-automatic cell injection manipulator (InjectMan NI2, Eppendorf Co.) were integrated to assemble a cell manipulation system (Fig.…”

“…Currently, urgent needs exist in the detection of food pathogens in cooking environment [11,17] and microbial growth in damp garments after the laundry washing process [10,14]. To meet these needs, we have recently developed a ultra-deep focusing range (UDF) Xuorescent microscope system and applied it successfully to the evaluation of microbial cell removal from fabrics [4], and to the automatic mapping of viable microbial cells being distributed in the surface layer of cotton fabrics [5]. The next step is to isolate those single-cells for their identiWcation.…”

Automatic Mapping of Viable Microbial Cells Distributed in the Surface Layer of Cotton Fabrics

“…However it was difficult to modify available models at a reasonable cost to fit our specific resolutional purpose. Thus we developed a novel microscopic system with an UDF system (Fujioka et al, 2006). In combination with the staining of viable cells with a fluorescent glucose derivative, 2-NBDG (Yoshioka et al, 1996;Matsuoka et al, 2003), the UDF system was found to be useful for the rapid evaluation of the efficacy of microbial cell removal (EMR) from fabrics in the specific case of Candida albicans microbes greater than 5 A/ m. From a practical viewpoint, however, it is essential to establish a spatial resolution as high as 1-2 m. In this study, we have critically revised the principal image processing software.…”