Recent Understanding of Soil Acidobacteria and Their Ecological Significance: A Critical Review.

Hesham Ali El-Enshasy,R Z Sayyed,Sadaf Kalam,Ni Luh Suriani,Daniel Joe Dailin,Iqbal Ahmad,Anirban Basu

doi:10.3389/fmicb.2020.580024

Abstract

Acidobacteria represents an underrepresented soil bacterial phylum whose members are pervasive and copiously distributed across nearly all ecosystems. Acidobacterial sequences are abundant in soils and represent a significant fraction of soil microbial community. Being recalcitrant and difficult-to-cultivate under laboratory conditions, holistic, polyphasic approaches are required to study these refractive bacteria extensively. Acidobacteria possesses an inventory of genes involved in diverse metabolic pathways, as evidenced by their pan-genomic profiles. Because of their preponderance and ubiquity in the soil, speculations have been made regarding their dynamic roles in vital ecological processes viz., regulation of biogeochemical cycles, decomposition of biopolymers, exopolysaccharide secretion, and plant growth promotion. These bacteria are expected to have genes that might help in survival and competitive colonization in the rhizosphere, leading to the establishment of beneficial relationships with plants. Exploration of these genetic attributes and more in-depth insights into the belowground mechanics and dynamics would lead to a better understanding of the functions and ecological significance of this enigmatic phylum in the soil-plant environment. This review is an effort to provide a recent update into the diversity of genes in Acidobacteria useful for characterization, understanding ecological roles, and future biotechnological perspectives.

Highlights

Prokaryotes, the unseen majority sustaining life on Earth, are involved in a multitude of interactions and biogeochemical processes having global ecological relevance, including decomposition, mineralization, storage, and release of nutrients (Sikorski, 2015)
Data available from published acidobacterial genome sequences reveal the presence of several genes involved in regulating carbon, nitrogen, and sulfur cycles, and those required for degrading different complex polysaccharides
The presence of genes encoding enzymes for the degradation of complex carbohydrate polymers like cellulose, hemicellulose, chitin, xylan, and lignin derivatives signifies their active participation in the carbon circuit as decomposers in soil (Ward et al, 2009; Wegner and Liesack, 2017; Banerjee et al, 2018; Belova et al, 2018) and cycling of organic matter derived from plants, fungi, and insects (King and Weber, 2007; García-Fraile et al, 2016; Dedysh and Damsté, 2018)

Summary

Introduction

Prokaryotes, the unseen majority sustaining life on Earth, are involved in a multitude of interactions and biogeochemical processes having global ecological relevance, including decomposition, mineralization, storage, and release of nutrients (Sikorski, 2015). Comprehensive studies targeting functional characteristics encoded in acidobacterial genomes may provide new vistas into ecological perspectives of phylum Acidobacteria. Data available from published acidobacterial genome sequences reveal the presence of several genes involved in regulating carbon, nitrogen, and sulfur cycles, and those required for degrading different complex polysaccharides.

Results

Conclusion