Can molecular genetic techniques improve our understanding of the role the microbial biomass plays in soil aggregation?

Abstract

Soil structure plays an integral role in regulating the physical, chemical, and biological functioning of soil systems and is essential for maintaining agricultural productivity. Many studies have investigated soil structure formation and stability. However, the underlying mechanisms behind its formation are still often unclear, including how soil microorganisms regulate this process via the aggregation of soil particles. In this review, we seek to summarise current information regarding how microorganisms influence aggregation and explore whether the application of molecular genetic techniques has potential to increase our understanding in this important area. Specifically, we review current information regarding the exact nature and role of microbially produced soil binding agents (extracellular polymeric substances, glomalin, hydrophobins and chaplins) and how different soil microorganisms (bacteria, archaea, fungi, protists) regulate and influence the production of these substances. Molecular genetic techniques have the capacity to provide new information regarding the genetic make-up of the soil microbial biomass, which could potentially be related to their function in soil and role in the aggregation of soil particles. However, more work is required to identify the key functional genes important for studying aggregation processes. Techniques better able to study the fine scale distribution of microorganisms and microbial products are also required to fully understand microbial interactions and functioning on a scale relevant to aggregation. Future developments in this area may offer an opportunity to improve our understanding of, and potentially manipulate, soil aggregation for the benefit of soil functioning and environments.