Pseudomonas gebzensis sp. nov., a Carotenoid-Producing Species Isolated from Solar Panels in Türkiye.

Abstract

Strain RP23018ST was isolated from the solar panels in Gebze, Türkiye. According to the phylogenetic analysis of 16S rRNA gene sequences, strain RP23018ST was classified as a member of the genus Pseudomonas, being most closely related to Pseudomonas cremoricolorata DSM 17059T (99.3%). Strain RP23018ST was Gram-stain-negative, rod-shaped, aerobic, motile, growing between temperature range of 4–35 °C. The polar lipids of strain RP23018ST consisted of phosphatidylethanolamine, di-phosphatidylglycerol, phosphatidylcholine, one unidentified phospholipid, and three unidentified aminolipids. It was determined that the main respiratory quinone of the RP23018ST strain was ubiquinone-9 (Q-9), which is a typical chemotaxonomic characteristic of the genus Pseudomonas. Major fatty acids were C16:0, summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), summed feature 8 (C18:1 ω6c and/or C18:1 ω7c), and C17:0 cyclo. Strain RP23018ST had a genome size of 4,944,510 bp and a G + C ratio of 63.0%. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between RP23018ᵀ and related Pseudomonas species were below 86.4% and 26.7%, respectively, clearly falling below the thresholds for species delineation. Strain RP23018ST produced a deep yellow carotenoid pigment with absorption maxima at 455 and 482 nm. Genome annotation revealed key carotenoid biosynthesis genes (crtX, crtY, crtI, crtZ), and the extracted pigment showed antioxidant activity in DPPH and FRAP assays. Polyphasic characterization, including the determination of overall genome relatedness indices, revealed that strain RP23018ST represents a novel species of the genus Pseudomonas, for which the name Pseudomonas gebzensis sp. nov. is proposed. The type strain is RP23018ST (= LMG 33436T = DSM 117295T).