Higuera-Llantén Sebastián, Pavlov María S, de Sousa Leandro P, Vásquez-Ponce Felipe, Parás-Silva Juan, Martínez José R W, Munita José M, Wozniak Aniela, García Patricia C, Ugalde Juan A, Blondel Carlos J, Lira Felipe, Martínez José Luis, Alcalde-Rico Manuel, Olivares-Pacheco Jorge
Grupo de Resistencia Antimicrobiana en Bacterias Patógenas y Ambientales, GRABPA, Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaiso, Chile.
Iniciativa Científica Milenio Para la Investigación Asociativa en Resistencia Antimicrobiana, MICROB-R, Santiago, Chile.
Antonie Van Leeuwenhoek. 2025 Sep 24;118(10):155. doi: 10.1007/s10482-025-02166-w.
Pseudomonas gelidaquae IB20 is a rod-shaped, motile bacterium distinguished by the presence of multiple polar flagella. The average nucleotide identity (ANIb) and average amino acid identity (AAI) values between P. gelidaquae IB20 and its closest phylogenetic relatives were all below the 95-96% thresholds currently accepted for delineating a novel species. Pseudomonas antarctica CMS 35 displayed the highest ANIb and AAI values, at 92.67% and 95.98%, respectively. A distinctive feature of the P. gelidaquae IB20 genome is the presence of a Type III Secretion System (T3SS), which is absent in the genomes of all closely related strains, making it the first Pseudomonas species isolated from Antarctica to carry this virulence system. Notably, we identified a novel candidate effector protein encoded within the T3SS gene cluster of P. gelidaquae IB20, exhibiting similarity to VopS T3SS effector proteins, which are predominantly found in Vibrio species. A comprehensive search of publicly available databases confirmed that this candidate effector protein is not present in any other Pseudomonas genome. Additionally, chemotaxonomic analysis showed that the dominant cellular fatty acids include summed feature 3 (C16:1ω7c/C15:0 iso 2-OH), C16:0, and C18:1ω7c. Based on extensive phenotypic and genotypic evidence, we propose that strain IB20 represents a novel species within the genus Pseudomonas, for which the name P. gelidaquae sp. nov. is proposed, with IB20 designated as the type strain.
嗜冷假单胞菌IB20是一种杆状、可运动的细菌，其特征是具有多条极生鞭毛。嗜冷假单胞菌IB20与其最接近的系统发育亲缘种之间的平均核苷酸同一性（ANIb）和平均氨基酸同一性（AAI）值均低于目前划定新物种所接受的95 - 96%阈值。南极假单胞菌CMS 35显示出最高的ANIb和AAI值，分别为92.67%和95.98%。嗜冷假单胞菌IB20基因组的一个显著特征是存在III型分泌系统（T3SS），所有密切相关菌株的基因组中均不存在该系统，这使其成为从南极洲分离出的首个携带这种毒力系统的假单胞菌物种。值得注意的是，我们在嗜冷假单胞菌IB20的T3SS基因簇中鉴定出一种新的候选效应蛋白，它与主要在弧菌属物种中发现的VopS T3SS效应蛋白具有相似性。对公开可用数据库的全面搜索证实，任何其他假单胞菌基因组中均不存在这种候选效应蛋白。此外，化学分类分析表明，主要的细胞脂肪酸包括总和特征3（C16:1ω7c/C15:0异2 - OH）、C16:0和C18:1ω7c。基于广泛的表型和基因型证据，我们提议菌株IB20代表假单胞菌属内的一个新物种，为此提出名为嗜冷假单胞菌（P. gelidaquae sp. nov.），并将IB20指定为模式菌株。
