A novel carotenoid-producing bacterium, Paenibacillus roseopurpureus sp. nov., isolated from Korean marine mud

Abstract

A novel bacterial strain, designated MBLB1832^T, was isolated from marine mud in Uljin, Republic of Korea. The strain was Gram-stain-positive, endospore-forming, and exhibited rod-shaped morphology. It grew at temperatures ranging from 10 to 45 °C (optimum 30 °C), at pH 6.0–9.0 (optimum 7.0), and in the presence of 0–2% NaCl (optimum 0%). Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain MBLB1832^T is closely related to Paenibacillus allorhizoplanae JJ-42^T, with 98.3% similarity. The predominant fatty acids were anteiso-C_15:0 and iso-C_16:0, and menaquinone-7 was identified as major isoprenoid quinone. Strain MBLB1832^T contained meso-diaminopimelic acid within the cell wall peptidoglycan. Polar lipid profiling indicated the presence of diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine as the major lipids. The genome of strain MBLB1832^T is 5.8 Mb in size with a G + C content of 46.9%. Average nucleotide identity, average amino acid identity, and DNA-DNA hybridization values confirmed that this strain is distinct from previously described species. Genome analysis revealed the presence of a complete C₃₀ carotenoid biosynthetic pathway, including genes encoding farnesyl diphosphate synthase, diapophytoene synthase, several diapophytoene desaturases, and distinct carotenoid glycosyltransferases and acyltransferases. Notably, the carotenoid pigments produced by the strain imparted a pink color, consistent with the coloration of its cell pellets. Based on these polyphasic taxonomic data, strain MBLB1832^T is proposed as a novel species of the genus Paenibacillus, for which the name Paenibacillus roseopurpureus sp. nov. is suggested (type strain MBLB1832^T = KCTC 43262^T = JCM 34221^T).