Present addresses: Monash Institute of Pharmaceutical Sciences, Monash University Parkville Campus, Parkville, Victoria, Australia;
Acidobacteria, Rubrobacteridae and Chloroflexi are abundant among very slow-growing and mini-colony-forming soil bacteria
Article first published online: 25 NOV 2010
© 2010 Society for Applied Microbiology and Blackwell Publishing Ltd
Volume 13, Issue 3, pages 798–805, March 2011
How to Cite
Davis, K. E. R., Sangwan, P. and Janssen, P. H. (2011), Acidobacteria, Rubrobacteridae and Chloroflexi are abundant among very slow-growing and mini-colony-forming soil bacteria. Environmental Microbiology, 13: 798–805. doi: 10.1111/j.1462-2920.2010.02384.x
- Issue published online: 1 MAR 2011
- Article first published online: 25 NOV 2010
- Received 8 August, 2010; accepted 14 October, 2010.
Easily visible colonies of bacteria continued to form on plates inoculated with soil and incubated for 24 weeks. Using two different media, 13% and 29% of easily visible colonies appeared after more than 12 weeks. In addition, 10% and 18% of all colonies had diameters of 25–200 µm (mini-colonies), which could not be readily seen with the unaided eye. Members of soil bacterial groups that are only rarely cultured, such as members of the subclass Rubrobacteridae of the phylum Actinobacteria, members of subdivisions 1 and 2 of the phylum Acidobacteria and members of three subphyla of the phylum Chloroflexi, were more abundant among the easily visible colonies and mini-colonies that developed after > 12 weeks of incubation. Our results indicate that there is a hidden culturable diversity of soil bacteria that may require laboratory study at colony sizes and incubation periods outside those commonly anticipated by most microbiologists. Working at these scales increases the likelihood of obtaining cultures from groups of soil bacteria that have generally eluded laboratory study by cultivation methods.