[17a-PB3-1~11] 12.6 Nanobiotechnology

[17a-PB3-7] Single-Cell Metabolic Activity Assessment Using Light Scattering of Formazan Dyes

〇(D)Hikaru Ikeda¹, Akira Tokonami¹, Koki Takenaga¹, Satohiro Itagaki¹, Hiroshi Shiigi¹ (1.Osaka Metro. Univ.)

Keywords:

Microorganisms,Dark-field microscopy,Ultraviolet irradiation

3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), a representative tetrazolium salt, readily permeates bacterial cell membranes and is intracellularly reduced by endogenous electron carriers to insoluble formazan, accompanied by a characteristic color change from yellow to purple. When E. coli cells stained with MTT were observed using dark-field microscopy, intense red scattered light originating from intracellularly accumulated formazan was clearly detected. In this study, we evaluated bacterial metabolic activity at the cellular level based on the formazan-derived scattering intensity. Furthermore, the applicability of this optical method to bacteria subjected to ultraviolet irradiation was investigated, demonstrating its potential for assessing metabolic activity in damaged or inactivated cells.