Taxonomic revision of the family Aurantimonadaceae: proposal of Dennerimonas gen. nov., Mesocryomonas gen. nov., Rathsackimonas gen. nov. and Plantimonas gen. nov., along with the reclassification of Jeongeupella Jiang et al. 2024 as a later heterotypic synonym of Antarcticirhabdus Du et al. 2023

Phylogenetic analysis of the genus Aureimonas, utilizing both 16S rRNA gene sequences and comprehensive whole-genome data, revealed its polyphyletic nature, necessitating a revision to accommodate phylogenetically distinct species. Based on established threshold values for genus demarcation - specifically, 16S rRNA gene similarity, Average Amino Acid Identity and Percentage of Conserved Proteins - a notably substantial divergence was observed within the genus Aureimonas, and the division of Aureimonas into four distinct genera is strongly supported. To address this, we propose the establishment of four new genera: Dennerimonas gen. nov., Mesocryomonas gen. nov., Rathsackimonas gen. nov. and Plantimonas gen. nov. These classifications accommodate species that are significantly divergent from the type species of Aureimonas, thereby more accurately reflecting their distinct evolutionary lineages. Additionally, Aureimonas glaciistagni is proposed to be reclassified within the genus Jiella as Jiella glaciistagni comb. nov. based on phylogenetic evidence indicating a closer evolutionary relationship to Jiella species than to other members of Aureimonas. Our analysis, which included assessments of 16S rRNA gene similarity, Average Nucleotide Identity, and digital DNA-DNA hybridization values exceeding species delineation thresholds, further supports the reclassification of Jeongeupella Jiang et al. 2024 as a later heterotypic synonym of Antarcticirhabdus Du et al. 2023.

Complete Genome and Plasmid Sequences of the Psychrotolerant Aureimonas Strain SA4125, Isolated from Antarctic Moss Vegetation

The complete genome sequences of Aureimonas sp. strain SA4125 and its native plasmid pSA4125 were determined. The genome sequence comprises 4,968,066 bp, with a GC content of 66.0%, and contains 4,691 coding DNA sequences (CDSs), 3 rRNA operons, and 50 tRNAs. The native plasmid comprises 131,777 bp, with a GC content of 62.3%, and contains 138 CDSs.

Aureimonas mangrovi sp. nov., a marine alphaproteobacterium isolated from mangrove sediment in Thailand

Two bacterial strains, designated as 1-4-3^T and 1-4-4, were isolated from a mangrove sediment cultured with coastal seawater. The cells were Gram-stain-negative, motile, short, rod-shaped bacteria with flagella. Growth occurred at 4-37 °C, pH 7.0-9.0, and 0-7% NaCl. The predominant fatty acids of the novel strains were C_18 : 1  ω7c, C_19 : 0 cyclo ω8c, C_18 : 0, and C_16 : 0. A phylogenetic analysis based on 16S rRNA gene sequences and whole genome phylogeny analysis based on distance matrix revealed an affiliation between the two strains and the genus Aureimonas, with closest sequence similarity to A. populi 4M3-2^T (96.41 and 96.64% similarity, respectively) and A. glaciistagni (96.01 and 96.23% similarity, respectively). The DNA G+C content of strain 1-4-3^T was 66.80 mol%. Strain 1-4-3^T displayed low DNA-DNA relatedness to A. populi 4M3-2^T, with an average nucleotide identity value of 77.47 % and digital DNA-DNA hybridization value of 22.83 %. Genotypic, chemotaxonomic, and phenotypic data indicate that strains 1-4-3^T and 1-4-4 represent a novel species of the genus Aureimonas, for which we propose the name Aureimonas mangrovi sp. nov. The type strain is 1-4-3^T (=LMG 31693^T=CGMCC 1.18507^T).

Culturable diversity of bacterial endophytes associated with medicinal plants of the Western Ghats, India

Bacterial endophytes are found in the internal tissues of plants and have intimate associations with their host. However, little is known about the diversity of medicinal plant endophytes (ME) or their capability to produce specialised metabolites that may contribute to therapeutic properties. We isolated 75 bacterial ME from 24 plant species of the Western Ghats, India. Molecular identification by 16S rRNA gene sequencing grouped MEs into 13 bacterial genera, with members of Gammaproteobacteria and Firmicutes being the most abundant. To improve taxonomic identification, 26 selected MEs were genome sequenced and average nucleotide identity (ANI) used to identify them to the species-level. This identified multiple species in the most common genus as Bacillus. Similarly, identity of the Enterobacterales was also distinguished within Enterobacter and Serratia by ANI and core-gene analysis. AntiSMASH identified non-ribosomal peptide synthase, lantipeptide and bacteriocin biosynthetic gene clusters (BGC) as the most common BGCs found in the ME genomes. A total of five of the ME isolates belonging to Bacillus, Serratia and Enterobacter showed antimicrobial activity against the plant pathogen Pectobacterium carotovorum. Using molecular and genomic approaches we have characterised a unique collection of endophytic bacteria from medicinal plants. Their genomes encode multiple specialised metabolite gene clusters and the collection can now be screened for novel bioactive and medicinal metabolites.