New Study Suggests Many Unknown Microbes in Soil

Soil microorganisms represent a significant portion of living matter on Earth and play a key role in ecosystem functions. Bacteria, fungi, archaea and viruses are the four microbial groups currently known to man. Bacterial presence in soil has been the most extensively studied, however with the environment at the forefront of worldwide focus, expanded research on fungal, archaeal, and viral communities is much needed.

In the study researchers used an RNA-based analysis technique to examine the richness of bacteria, fungi, archaea, and viruses in samples collected from prairie, desert, and rainforest soils. These sites were specifically targeted because they represent globally dominated ecosystem types and are broad in aridity and productivity. Results showed that unique archaeal or fungal units appeared to rival or exceed unique bacterial units in each of the soil samples.

"In this first study, to comprehensively survey rival communities using a metagenomic approach, we found that soil viruses are taxonomically diverse and distinct from the communities of viruses found in other environments that have been surveyed using a similar approach," say the researchers. "Within each of the four microbial groups, we observed minimal taxonomic overlap between sites, suggesting that soil archaea, bacteria, fungi, and viruses are globally as well as locally diverse."

Journal reference: N. Fierer, M. Breitbart, J. Nulton, P. Salamon, C. Lozupone, R. Jones, M. Robeson, R.A. Edwards, B. Felts, S. Rayhawk, R. Knight, F. Rohwer, R.B. Jackson. 2007. Metagenomic and small-subunit rRNA analyses reveal the genetic diversity of bacteria, archaea, fungi, and viruses in soil. Applied and Environmental Microbiology, 73. 21: 7059-7066.