Assessing Microbial Community Patterns During Incipient Soil Formation From Basalt

Aditi Sengupta, James C. Stegen, Antonio A. Meira Neto, Yadi Wang, Julia W. Neilson, Jon Chorover, Peter A. Troch, Raina M. Maier

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Microbial dynamics drive the biotic machinery of early soil evolution. However, integrated knowledge of microbial community establishment, functional associations, and community assembly processes in incipient soil is lacking. This study presents a novel approach of combining microbial phylogenetic profiling, functional predictions, and community assembly processes to analyze drivers of microbial community establishment in an emerging soil system. Rigorous submeter sampling of a basalt-soil lysimeter after 2 years of irrigation revealed that microbial community colonization patterns and associated soil parameters were depth dependent. Phylogenetic analysis of 16S rRNA gene sequences indicated the presence of diverse bacterial and archaeal phyla, with high relative abundance of Actinomyceles on the surface and a consistently high abundance of Proteobacteria (Alpha, Beta, Gamma, and Delta) at all depths. Despite depth-dependent variation in community diversity, predicted functional gene analysis suggested that microbial metabolisms did not differ with depth, thereby suggesting redundancy in functional potential throughout the system. Null modeling revealed that microbial community assembly patterns were predominantly governed by variable selection. The relative influence of variable selection decreased with depth, indicating unique and relatively harsh environmental conditions near the surface and more benign conditions with depth. Additionally, community composition near the center of the domain was influenced by high levels of dispersal, suggesting that spatial processes interact with deterministic selection imposed by the environment. These results suggest that for oligotrophic systems, there are major differences in the length scales of variation between vertical and horizontal dimensions with the vertical dimension dominating variation in physical, chemical, and biological features.

Original languageEnglish (US)
Pages (from-to)941-958
Number of pages18
JournalJournal of Geophysical Research: Biogeosciences
Issue number4
StatePublished - Apr 2019


  • bacterial/archaeal phylogenetic analysis
  • incipient soil system
  • null modeling
  • scale and dimensions of variation
  • terrestrial basalt

ASJC Scopus subject areas

  • Soil Science
  • Forestry
  • Water Science and Technology
  • Palaeontology
  • Atmospheric Science
  • Aquatic Science
  • Ecology


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