Kathiresan Akila, Kim Hyung-Seop, Dong Ke, Srinivasan Sathiyaraj, Lee Sang-Seob
Department of Integrative Biotechnology, Natural Science Campus, Sungkyunkwan University, 2066, Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do, 16419, Republic of Korea.
Department of Marine Biology, College of Ocean Science and Technology, Kunsan National University, 558 Daehak-ro, Gunsan-si, Jeollabuk-do, 54150, Republic of Korea.
Curr Microbiol. 2025 Aug 18;82(10):463. doi: 10.1007/s00284-025-04433-5.
Strain MF5-112 is a Gram-negative, aerobic, non-motile, ovoid, and non-flagellated bacterium with yellow pigmentation that exhibits oxidase-positive and catalase-negative characteristics. It was isolated from tidal mudflat sediment at a clam farm in Gochang, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain MF5-112 belongs to the family Flavobacteriaceae. The closest relative was the type strain of Polaribacter huanghezhanensis KCTC 32516 (97.1% 16S rRNA gene sequence similarity), followed by P. pacificus HRA130-1 (96.3%). The major polar lipids were phosphatidylethanolamine, one unidentified phospholipid, two unidentified aminophospholipids, and two unidentified aminolipids. The predominant cellular fatty acids included iso-C, iso-C 3-OH iso-C 3-OH, anteiso-C iso-C G iso-C and Cω6c, with menaquinone-6 identified as the major respiratory quinone. The strain MF5-112 exhibits a dual nitrogen metabolism capability, involving both assimilatory nitrate reduction and partial denitrification, which is essential for nitrogen cycling in marine environments. In 72 h, it reduced ammonia nitrogen (NH₄⁺-N) by 59.5% and nitrate nitrogen (NO₃⁻-N) by 42.0%, with ammonia as the preferred nitrogen source. The genome spans 2.6 Mbp with a G + C content of 31.3%, containing 2,454 genes, including 14 related to nitrogen metabolism pathways. Essential genes such as nit-6, nasBDC, nirK, and nirS facilitate the conversion of nitrate and nitrite to ammonia and further reduce nitrite to nitric oxide (NO) and nitrous oxide (N₂O). These characteristics suggest that strain MF5-112 plays a role in nitrogen cycling within sedimentary ecosystems. Based on its unique genetic and phenotypic properties, strain MF5-112 represents a novel species of the genus Polaribacter, for which the name Polaribacter gochangensis sp. nov. is proposed. The type strain is MF5-112 (= KEMB 23950 = KCTC 102318 = JCM 37723).
菌株MF5-112是一种革兰氏阴性、需氧、不运动、卵形且无鞭毛的细菌，带有黄色色素，具有氧化酶阳性和过氧化氢酶阴性的特征。它是从韩国固城一个蛤养殖场的潮间带泥滩沉积物中分离出来的。基于16S rRNA基因序列比较的系统发育分析表明，菌株MF5-112属于黄杆菌科。最接近的亲缘种是黄河站极地杆菌KCTC 32516的模式菌株（16S rRNA基因序列相似性为97.1%），其次是太平洋极地杆菌HRA130-1（96.3%）。主要极性脂类为磷脂酰乙醇胺、一种未鉴定的磷脂、两种未鉴定的氨基磷脂和两种未鉴定的氨基脂类。主要的细胞脂肪酸包括异-C、异-C₃-OH、异-C₃-OH、anteiso-C、异-C₆、异-C₆和Cω6c，以甲基萘醌-6作为主要呼吸醌。菌株MF5-112具有双重氮代谢能力，涉及同化硝酸盐还原和部分反硝化作用，这对海洋环境中的氮循环至关重要。在72小时内，它将氨氮（NH₄⁺-N）降低了59.5%，将硝酸盐氮（NO₃⁻-N）降低了42.0%，以氨作为首选氮源。该基因组跨度为2.6 Mbp，G+C含量为31.3%，包含2454个基因，其中14个与氮代谢途径相关。诸如nit-6、nasBDC、nirK和nirS等必需基因促进硝酸盐和亚硝酸盐向氨的转化，并进一步将亚硝酸盐还原为一氧化氮（NO）和一氧化二氮（N₂O）。这些特征表明菌株MF5-112在沉积生态系统中的氮循环中发挥作用。基于其独特的遗传和表型特性，菌株MF5-112代表了极地杆菌属的一个新物种，为此提出了黄河站极地杆菌（Polaribacter gochangensis sp. nov.）这一名称。模式菌株为MF5-112（=KEMB 23950=KCTC 102318=JCM 37723）。
