# Pontibacter rufus sp. nov., Pontibacter humidus sp. nov. and Pontibacter coccineus sp. nov. isolated from UV-irradiated soil in Korea

## TL;DR

Three new species of bacteria, Pontibacter rufus, Pontibacter humidus, and Pontibacter coccineus, were discovered in UV-treated soil in South Korea.

## Contribution

The discovery and classification of three novel Pontibacter species based on genetic, biochemical, and phylogenetic analyses.

## Key findings

- The three new species were identified through 16S rRNA gene sequencing and phylogenetic analysis.
- Genome size and fatty acid profiles confirmed the distinctiveness of the new species.
- DNA-DNA hybridization and average nucleotide identity values supported the classification as novel species.

## Abstract

Three novel bacterial strains, 172403-2T, BT310T and BT731T, were isolated from UV-irradiated soil samples collected in South Korea. All strains are Gram-negative, aerobic, non-motile and grow at 20–35 °C, optimally at 30 °C and pH 7.0. The optimal NaCl concentration for strains 172403-2T and BT310T is 1.5%, while strain BT731T grows optimally in the absence of NaCl (0.0%). Phylogenetic analysis based on 16S rRNA gene sequences positioned these strains within the genus Pontibacter, with strain 172403-2T closest to Pontibacter chitinilyticus (95.96%), BT310T to Pontibacter pudoricolor (97.87%) and BT731T to Pontibacter virosus (98.06%). Cellular fatty acid profiles identified C15:0 iso and Summed Feature 4 as predominant fatty acids. All strains contained ubiquinone MK-7 and phosphatidylethanolamine as major respiratory quinone and primary polar lipids, respectively. Genome sizes were 5.08 Mb for 172403-2T, 4.29 Mb for BT310T and 4.66 Mb for BT731T, with average nucleotide identity and digital DNA–DNA hybridization values with other Pontibacter species ranging between 70.41%–88.56% and 11.55%–24.66%, respectively. These biochemical, chemotaxonomic and phylogenetic analyses confirm that strains 172403-2T, BT310T and BT731T represent three novel species of Pontibacter, proposed as Pontibacter rufus sp. nov. (172403–2T = KCTC 62072 T=NBRC 114967T), Pontibacter humidus sp. nov. (BT310T = KCTC 72363T = NBRC 114846T) and Pontibacter coccineus sp. nov. (BT731T = KCTC 92910T = NBRC 116069T).