AUTHOR=Ye Yu-Qi , Hao Zhi-Peng , Yue Yu-Yan , Ma Lu , Ye Meng-Qi , Du Zong-Jun 

TITLE=Characterization of Kordiimonas marina sp. nov. and Kordiimonas laminariae sp. nov. and Comparative Genomic Analysis of the Genus Kordiimonas, A Marine-Adapted Taxon

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.919253

DOI=10.3389/fmars.2022.919253

ISSN=2296-7745

ABSTRACT=<p>Two novel rod-shaped and Gram-negative bacterial strains, designated A6E486<sup>T</sup> and 5E331<sup>T</sup>, were isolated from a coastal sediment sample taken from Xiaoshi Island, Weihai, China, and a fresh kelp sample collected from a kelp culture area, Rongcheng, China, respectively. Growth of strain A6E486<sup>T</sup> occurred at 20°C–43°C (optimum, 33°C–35°C) at pH 5.5–7.5 (optimum, 6.5) and in the presence of 1.0%–5.5% (w/v) NaCl (optimum, 2.5%–3.0%). Strain 5E331<sup>T</sup> grew with 1.5%–5.0% (w/v) NaCl (optimum, 3.0%) at 15°C–40°C (optimum, 33°) and pH 6.0–8.5 (optimum, 7.0). The similarity of 16S rRNA gene sequence between the two strains was 95.2%. The phylogenetic analysis based on 16S rRNA gene sequence showed that strains A6E486<sup>T</sup> and 5E331<sup>T</sup> belong to the genus <italic>Kordiimonas</italic>, sharing the highest similarity to the genus <italic>Kordiimonas</italic> (94.6%–96.8%, 94.9%–96.1%, respectively). Strains A6E486<sup>T</sup> and 5E331<sup>T</sup> had percentage of conserved protein (POCP) values of 56.0%–67.3% and average nucleotide identity (ANI) values of 68.8%–73.1% to members of the genus <italic>Kordiimonas</italic>. The major polar lipids detected in the two strains were phosphatidylethanolamine (PE), phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), and unidentified glycolipids, aminolipids, and lipids. The predominant respiratory quinone of the two strains was Q-10. Based upon the results presented in this study, strains A6E486<sup>T</sup> and 5E331<sup>T</sup> represent two novel species of the genus <italic>Kordiimonas</italic>, for which the names <italic>Kordiimonas marina</italic> and <italic>Kordiimonas laminariae</italic> are proposed with the type strains A6E486<sup>T</sup> (= KCTC 82758<sup>T</sup> = MCCC 1H00470<sup>T</sup>) and 5E331<sup>T</sup> (= KCTC 92199<sup>T</sup> = MCCC 1H00515<sup>T</sup>), respectively. Comparative genomic analysis showed that seven species of the genus <italic>Kordiimonas</italic> shared 1,258 core genes and had differences in carbohydrate metabolism, energy metabolism, and cofactor and vitamin metabolism. The pan-genome of the genus <italic>Kordiimonas</italic> was open. The prediction of secondary metabolites showed that most strains of the genus <italic>Kordiimonas</italic> had the ability to produce homoserine lactones, one of the most important signal molecules in the quorum-sensing system of Gram-negative bacteria. Additionally, numerous genes involved in bacterial defense, motility and chemotaxis, cold adaptation, and environment stress response were found in the genus <italic>Kordiimonas</italic>, indicating the marine-adapted lifestyle of members of the genus <italic>Kordiimonas</italic>.</p>