Abstract
The colony formation of sulfate-reducing bacteria, Desulfovibrio desulfuricans and Desulfotomaculum orientis, on agar plates well fitted the theoretical curve of the FOR model proposed by Hattori (1985). The estimates of λ for both strains dropped from 5 to 1 day-1 with cultivation in a liquid medium or starvation in a buffer solution, while that of tr was not affected so much. The estimates of λ and tr for D. desulfuricans were markedly affected by incubation temperature and lactate concentration in the agar medium. Both factors also affected the tr value for D orientis, however only incubation temperature affected the λ value for the latter organism.
