Comparative analysis on whole genome sequences of type strains in the genus of Neorhizobium

The genus Neorhizobium belongs to the family Rhizobiaceae, and there are only eight validly published species within this genus. To investigate the molecular mechanisms and genetic characteristics of these eight strains, we used Prodigal and other software to predict and annotate genes, perform phylogenetic analysis based on whole genome sequences, and compare and analyze the genomes. The predictions showed that the CDS (Coding Sequences), GC content, rRNA, and tRNA ranges are 4 471 - 6 669, 60.0% - 61.6%, 3 - 9, and 43 - 51, respectively. Comparative analysis of the genomes identified 2 563 orthologous gene clusters that are shared among all strains while only few specific gene clusters are independently inherent. By using average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), and phylogenetic tree, we found that CCBAU 05176^T and T17_20^T exhibit the highest homology, while T786^T and NTR19^T show the greatest genetic distance. Based on comparative analysis of COG (Cluster of Orthologous Groups of Proteins) and KEGG (Kyoto Encyclopedia of Genes and Genomes) classifications, we found that the annotated gene functions are generally consistent, but the number and proportion of xenobiotic biodegradation and metabolism genes are significantly higher in strain SL-1^T than in other strains. Taken together, our findings help to lay a foundation for the future systematic taxonomy and application of the Neorhizobium genus in different ecosystems.