Advanced prokaryotic systematics: the modern face of an ancient science

Abstract

Prokaryotic systematics is one of the most progressive disciplines that has embraced technological advances over the last century. The availability and affordability of new sequencing technologies and user-friendly software have revolutionised the discovery of novel prokaryotic taxa, including the identification and nomenclature of uncultivable microorganisms. These advances have enabled scientists to resolve the structure of complex heterogenous taxon and to rectify taxonomic status of misclassified strains due to errors associated with the sensitivity and/or reproducibility of phenotypic approaches. Time- and labour-intensive experimental characterisation of strains could be replaced with determining the presence or absence of genes or operons responsible for phenotypic and chemotaxonomic properties, such as the presence of mycolic acids and menaquinones. However, the quality of genomic data must be acceptable and phylogenomic threshold values for interspecies and supraspecies delineation should be carefully considered in combination of genome-based phylogeny for a reliable and robust classification. These technological developments have empowered prokaryotic systematists to reliably identify novel taxa with an understanding of community ecology and their biosynthetic and biodegradation potentials.

Keywords: AAI, Average amino acid identity; ANI, Average nucleotide identity; Average amino acid identity; CPR, Candidate Phyla Radiation; GBDP, Genome BLAST Distance Phylogeny; Next generation sequencing; POCP, Percentage of conserved proteins; TYGS, Type (Strain) Genome Server; average nucleotide identity; dDDH, Digital-DNA-DNA hybridisation; digital DNA-DNA hybridisation; percentage of conserved proteins; phylogenomic analyses; prokaryotic systematics.