Acidobacteria – The exploration of the unknown abundance

PI: Dr. Katharina Huber

The Acidobacteria represent a globally widespread phylum, which have been detected not only in moderate environments like soil but also in extreme habitats like cave paintings, polar deserts, and hot springs. Besides the Proteobacteria, Actinobacteria and Firmicutes, the Acidobacteria dominate the soil environment and constitute here 5-70% of the active bacterial community. Despite these high abundance values, only 57 acidobacterial species have been isolated and described so far. Due to this low number of isolates, the potential role of the Acidobacteria in the biogeochemical cycles is quite unknown. To better understand the numerical abundance and function of Acidobacteria in soils, we analysed the acidobacterial community composition of 138 subtropical savannah soil samples by 16S rRNA gene high-throughput amplicon sequencing in combination with multivariate statistical analysis. Based on the gained knowledge, improved cultivation strategies enabled the isolation of one third of all currently cultured acidobacterial strains including the first described representatives of the important classes Blastocatellia and subdivision 6 Acidobacteria, recently proposed as ‘Vicinamibacteria’. Future research will combine detailed physiological characterization of the new isolates with genome sequencing of selected strains to provide insights into their potential role in soil biogeochemical cycling and to answer the question why Acidobacteria are such a successful group of soil microorganisms.

Selected references

  1. Huber, K.J., Wüst, P.K., Rohde, M., Overmann, J., Foesel, B.U. (2014) Aridibacter famiduransgen. nov., sp. nov. and Aridibacter kavangonensissp. nov., two novel members of subdivision 4 of the Acidobacteria isolated from semiarid savannah soil. Int J Syst Evol Microbiol.64(Pt 6):1866-1875.
  2. Huber, K.J., Geppert, A.M., Wanner, G., Fösel, B.U., Wüst, P.K., Overmann J. (2016) The first representative of the globally widespread subdivision 6 Acidobacteria, Vicinamibacter silvestrisgen. nov., sp. nov., isolated from subtropical savannah soil. Int J Syst Evol Microbiol.66(8):2971-2979.
  3. Huber, K.J., Geppert, A.M., Groß, U., Luckner, M., Wanner, G., Cooper, P., Abakah, J., Janssen, I., Overmann, J. (2017) Aridibacter nitratireducenssp. nov., a member of the family Blastocatellaceae, class Blastocatellia, isolated from an African soil. Int J Syst Evol Microbiol.67(11):4487-4493.