Site-Specific Conditions Change the Response of Bacterial Producers of Soil Structure-Stabilizing Agents Such as Exopolysaccharides and Lipopolysaccharides to Tillage Intensity

Abstract

Bacterial Response to Tillage Intensity to tillage intensity had higher potential for exopolysaccharide and lipopolysaccharide production specifically under reduced tillage. This could be especially crucial for aggregate stability, as polysaccharides produced by different taxa have different "gluing" efficiency. Overall, our data indicate that tillage intensity could affect aggregate stability by both influencing the absolute abundance of genes involved in the production of exopolysaccharides and lipopolysaccharides, as well as by inducing shifts in the community of potential polysaccharide producers. The effects of tillage intensity depend mostly on site-specific conditions.

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

“…In these studies, genes related to the production of exopolysaccharides and lipopolysaccharides ( wza, algE, algJ, wcaB, wcaF, wcaK, amsJ, kpsE, epsG, epsA, sacB, wzt, lptF, lptG, lptC ) were observed to increase in biocrusts compared to bulk soil samples (Cania, Vestergaard, Kublik, et al, 2020). Similar techniques were also used to demonstrate that the improved aggregate stability associated with reduced tillage practices at some sites was associated with an increase in the abundance of genes associated with exopolysaccharide and lipopolysaccharide production (Cania, Vestergaard, Suhadolc, et al, 2020), although at others no differences were observed (Cania et al, 2019; Cania, Vestergaard, Suhadolc, et al, 2020). It was noted by the authors of this study that due to the lack of gene sequence data regarding the production of EPS by other organisms, these studies are biased towards bacteria (Cania, Vestergaard, Suhadolc, et al, 2020).…”

“…Similar techniques were also used to demonstrate that the improved aggregate stability associated with reduced tillage practices at some sites was associated with an increase in the abundance of genes associated with exopolysaccharide and lipopolysaccharide production (Cania, Vestergaard, Suhadolc, et al, 2020), although at others no differences were observed (Cania et al, 2019; Cania, Vestergaard, Suhadolc, et al, 2020). It was noted by the authors of this study that due to the lack of gene sequence data regarding the production of EPS by other organisms, these studies are biased towards bacteria (Cania, Vestergaard, Suhadolc, et al, 2020). It was also noted that the actual production of exo‐ and lipo‐polysaccharides could differ depending on environmental factors (carbon availability, temperature, soil pH, etc) and the application of more metatranscriptomics analysis of the soil environment would be desirable to examine these factors given that even though genes may be present, they may not always be actively expressed (see further discussion below) (Cania et al, 2019).…”

“…the Kyoto Encyclopaedia of Genes and Genomes (KEGG), the National Centre for Biotechnology Information (NCBI)] are currently used to relate the genes extracted from a soil with particular types of microorganisms or functions. These databases can differ significantly (Nannipieri et al, 2020), and while they are rapidly evolving, they are currently dominated by sequences from fast‐growing bacteria (Cania et al, 2019; Cania, Vestergaard, Suhadolc, et al, 2020; Thiele‐Bruhn et al, 2020), partly due to the relative ease with which these organisms can be cultured and analysed. However, the soil microbial biomass also contains slow‐growing bacteria, archaea, fungi and protists that play important roles in aggregation.…”

Plant Microbiota Beyond Farming Practices: A Review

“…Thus, taxonomical data generated through metagenomic approaches should be considered cautiously depending on the taxonomical level and specific biological and/or ecological functions. While both conventional and conservation tillage increase the abundance of Actinobacteria (Hartman et al, 2018;Babin et al, 2019), Cania et al (2020) demonstrated that low tilling intensity favors those harboring a higher potential to produce exo-and lipopolysaccharides. These biomolecules are crucial in soil macroaggregate formation and stability and, therefore, play crucial roles in preventing severe erosion events and ecological niche homogenization.…”

Managing Soils for Recovering from the COVID-19 Pandemic

“…Only in areas with sufficient water storage in the soil can yield losses that remain within acceptable limits [24]. However, the geographical distribution of soils and their quality and health varies spatially on all scales, from climatic zones to individual fields [25]. Therefore, not only the protection of soil and the preservation of its functions, but also the use of soils under the aspect of resilience to crises such as the COVID-19 pandemic must be approached site-specifically.…”