A novel method for detection and counting of single bacteria in a wide field using an ultra-high-sensitivity TV camera without a microscope

Abstract

We describe a novel method for enumeration of bacteria, based on the principle that small, light emitting particles on a flat surface can be easily and rapidly detected and counted using an ultra-high-sensitivity TV camera. To test this method, we obtained TV images of individual cells of a luminous bacterium on a membrane filter without the use of a microscope. The positions of the luminous points in the TV images were almost the same as the positions of the bacterial colonies after growth. Our results show that the single cells can be efficiently detected and counted by our method if they emit light or can be stimulated to emit light.

A Photon Counting Tv Camera Equipped With an Image Guide for Rapid Detection and Counting of Single Bacteria in a Wide Field

“…strain Ohtake 3-1 1 was used as the standard. It was cultivated in the same manner as previously reported (Masuko et al, 1991a).…”

“…One of these cameras was equipped with two photographic lenses (Nikkor 28 mm F2S, Nikon, Japan, plus Close-up Lens No. 10, Kenko, Japan) (Masuko et al, 1991a). This TV camera, designated as camera L, was used for comparison to our presently developed TV camera.…”

“…Specifications of the image guide are as follows: numerical aperture, 1.0; ratio of the diameters between the incident and the transmitted sides, 45 mm115 mm; diameter of each optical fiber, 10 km. Further details on the instrumentation are described in the previous paper (Masuko et al, 1991a). Proceduresfor observarion.…”

“…Specifically, the ultra-high sensitivity of the TV camera can compensate for the low light collecting power of the lens which has a low numerical aperture due to the wide field of observation. Nevertheless, it took about 50 min to detect Photobacterium cells (Masuko et al, 1991a) and 10 min to detect Escherichia coli cells that were induced to chemiluminesce (Masuko et al, 1991b). For practical appli-'To whom correspondence should be addressed.…”

“…In this paper, we report our results on the evaluation of a photon counting TV camera system using an image guide in comparison with the lens-coupled TV camera system previously used. As in the previous paper (Masuko et al, 1991a), the luminous bacterium was chosen as the standard in this study, because it emits light without special treatment.…”