Genome-based classification of Halonovum salinarum gen. nov., sp. nov., and Halonovum rutilum sp. nov. - Research article

Sep 29, 2026

Haloarchaea in the class Halobacteria include hundreds of valid species, and discovery of novel halophilic archaea supports understanding evolutionary, ecological, and taxonomic diversity. Within Haloferacaceae, Halonarum species were previously reclassified and new members prompted expansion. Using genome- and polyphasic approaches, two strains from a Korean solar saltern were identified as distinct species and placed into a newly proposed genus, Halonovum.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages12

Reading Time30 min

AccessFree to download

Abstract

Background

Results

Conclusions

Background

Halophilic archaea and haloarchaea diversity

Genus Halobaculum

Genus Halorarum

Hwang et al. BMC Microbiology (2026) 26:6 [https://doi.org/10.1186/s12866-025-04481-8](https://doi.org/10.1186/s12866-025-04481-8) BMC Microbiology RESEARCH Open Access Genome-based classification of Halonovum salinarum gen. nov., sp. nov., and Halonovum rutilum sp. nov., two novel halophilic archaea isolated from a solar saltern Chi Young Hwang 1, Eui-Sang Cho2, Ki-Eun Lee3, Eun-Young Lee3 and Myung-Ji Seo 1,4,5* Abstract Background Haloarchaea, belonging to the class Halobacteria, currently include more than 400 validly published species. The isolation of novel halophilic archaea is important for understanding their evolutionary, ecological, and taxonomic diversity. Within the family Haloferacaceae, the genus Halorarum comprises two species reclassified from Halobaculum and one newly described species. In this study, we propose a new genus, Halonovum, to accommodate two novel species that are phylogenetically related to the genera Halobaculum and Halorarum. Results Two novel halophilic archaeal strains, MBLA0143T and MBLA0147T, were isolated from a solar saltern in Republic of Korea. Strain MBLA0143T and MBLA0147T showed the highest 16 S rRNA gene similarity (94 . 5% and 94. 3%) to Halorarum salinum NJ-3-1T, and these two isolates were confirmed to represent different species, with 93. 7% 16 SrRNA gene similarity between them. Their growth occurred at 25–55 °C (optimum, 40 °C), 2.5–5.1 M NaCl (optimum, 4.2 M), 0.1–1.0 M MgCl2 (optimum, 0.1 M), and pH 5.0–9.0 (optimum, 6.0–7.0). The predominant polar lipids detected in these two strains included phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester. The genome size and G + C content of strain MBLA0143T were 3.58 Mbp and 68. 3%, while those of strain MBLA0147T was 4.29 Mbp and 67. 6% . The OrthoANI (74 .6–76. 1% for MBLA0143ᵀ and 73.8–75. 3% for MBLA0147ᵀ), AAI (66 .9–71. 7% for MBLA0143ᵀ and 66.9–67. 8% for MBLA0147ᵀ), and isDDH (20 .8–21. 5% for MBLA0143ᵀ and 20.0–20. 7% for MBLA0147ᵀ) values between these two species and currently recognized Halobaculum and Halorarum species support their placement in different genera within the family Haloferacaceae, based on the genus del imitation thresholds. In addition, phylogenomic analyses confirmed that the two novel species are distinct from species of other genera. Conclusions These results combined with polyphasic taxonomic analyses support that strains MBLA0143T and MBLA0147T represent a novel genus related to the genera Halobaculum and Halorarum. Two novel species are proposed to be classified into a novel genus and species, named Halonovum salinarum gen. nov., sp. nov. and Halonovum rutilum sp. nov. The type strains are MBLA0143T (= KCTC 4317T = JCM 36640T) and MBLA0147T (= KCTC 4319T = JCM 36641T) . *Correspondence: Myung-Ji Seo [mjseo@inu.ac.kr](mjseo@inu.ac.kr) Full list of author information is available at the end of the article © The Author(s) 2025. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit [http://creati](http://creati)[vecommons.org/l](vecommons.org/l)icenses/by-nc-nd/4.

FAQs

What is the main goal of the study?

To classify two novel halophilic archaeal strains from a Korean solar saltern using genome-based and polyphasic taxonomic analyses and to propose a new genus and species placement.

How were the two novel strains determined to represent different species?

They showed the highest 16S rRNA gene similarities to Halorarum salinum NJ-3-1T, while the 16S rRNA gene similarity between the two isolates was 93.7%, supporting that they are different species.

Which genomic metrics supported placing the strains into different genera within Haloferacaceae?

OrthoANI, AAI, and isDDH values between the isolates and currently recognized Halobaculum and Halorarum species supported placement into different genera based on genus delineation thresholds.

Sep 29, 2026

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