Incubation time and media requirements of culturable bacteria from different phylogenetic groups

Abstract

Previously, time courses of the colony formation process of soil bacteria on agar plates were simulated by colony-forming curves (CFCs). Bacteria were isolated from the colonies that appeared during an incubation period corresponding to each component curve of the CFC, respectively, and they were placed into groups I, II, III or IV, which were based on the order of colonization, so that their physiological characteristics could be studied (Gorlach, K. et al. (1994) J. Gen. Appl. Microbiol. 40, 507–517). We report here on the results of phylogenetic analysis of the isolates from each CFC group. A wide variety of eubacteria were included in the collection. Strains closely related to Arthrobacter were those from CFC groups I or II, groups of faster growers, and strains in Proteobacteria α-subdivision were those from groups III or IV, which grew more slowly. In contrast, some phylogenetic groups, such as Firmicutes low G+C, Cytophaga/Flexibacter/Bacteroides and Proteobacteria β-divisions exhibited heterogeneity regarding CFC grouping. As for their requirement for media, isolates belonging to the Cytophaga/Flexibacter/Bacteroides division, the Proteobacteria α-subdivision, β-subdivision and the Firmicutes high G+C division, except for Arthrobacter-related strains, were oligotrophic bacteria. In contrast, those belonging to the Firmicutes low G+C division, the Proteobacteria γ-subdivision and the A. globiformis-related group in the Firmicutes high G+C division were not oligotrophic.