Author(s)

Jong-Shik Kim, David E. Crowley

Department of Environmental Sciences, University of California, Riverside, USA.
Gyeongbuk Institute for Marine Bioindustry, Uljin, Gyeongbuk, Republic of Korea.

The microbial community structure in various microaggregates in a loamy sand soil was investigated. The microaggregates were separated into outer and inner aggregates using a series of soil washes. Further physical fractionation of inner aggregates was achieved by separation into coarse and fine sand as macroaggregate fractions, coarse and fine silt as microaggregate fractions, and clay. Research on microbial communities and soil microaggregates can aid in our understanding of soil microhabitats and microorganisms in soil structures, with applications that may contribute to increasing crop production and maintaining sustainable agriculture. In order to study the microbial community structure of aggregates, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was performed using 16S rRNA genes. The PCR-DGGE of the Bacteria Actinomycetes and Archaea showed divergent results between the different aggregate fractions. The results showed that the bacterial community structure was highly similar between bulk soil and clay; the inner aggregate community structure of Actinomycetes was closely related between coarse and fine sand and coarse silt, and the Archaea community structure of outer and inner aggregates was more similar than that of total bacteria or Actinomycetes.

Soil Aggregate; Microbial Community; Fractionation

Kim, J. and E. Crowley, D. (2013) Size fractionation and microbial community structure of soil aggregates. Journal of Agricultural Chemistry and Environment, 2, 75-80. doi: 10.4236/jacen.2013.24011.