DETECTION OF CELL VIABILITY IN CULTURES OF HYPERTHERMOPHILES

Fluorescent dyes were assessed with regard to their ability to discrim inate between viable and non-viable cells of hyperthermophilic archaea and bacteria. Using bis-(1,3-dibutylbarbituric acid) trimethine oxono l (DiBAC(4)(3)), a membrane potential-sensitive probe, a safe and rapi d discrimination of viable cells was possible by fluorescence microsco py. Single viable individuals, identified by DiBAC(4)(3), were selecti vely isolated from mixtures of viable and dead cells by the use of a l aser microscope ('optical tweezers') and grown in pure culture.