Comprehensive multi-analytical characterization of a novel Arthrobacter strain producing natural bacterioruberin for...

Bacterioruberin is a C50 carotenoid gaining more interest because of its important biological properties. This study aimed to the identification and characterization of a bacterial strain producing this attracting carotenoid, Arthrobacter sp. strain CP30. Phylogenetic analysis based on 16S rRNA gene sequences and whole genome comparison showed that strain CP30 belongs to the Arthrobacter agilis group with Arthrobacter bussei being the closest relative. Sequence similarity of the 16S rRNA gene of CP30 to described Arthrobacter species as well as average nucleotide identity values indicate that CP30 represents a new species within the genus Arthrobacter. The strain has been cultivated under controlled fermentation parameters, and the obtained biomass was investigated for carotenoids and lipids quali-quantitative profiles characterization. The biomass extracts enriched in bacterioruberin have been evaluated for antimicrobial and antioxidant properties. The bacterioruberin produced by the strain reached up a carotenoid titer of 1.28 mg L^-1 in 72 h, with a yield of 327.67 ± 6.6 μg g^-1 of dry biomass, a productivity of 0.02 mg/L/h, and showed an IC₅₀ value of 3.87 μg/mL. The most abundant fatty acids were 12-methyltetradecanoic, 14-methylpentadecanoic and 13-methyltetradecanoic. Whereas, among the intact lipids, glycolipids, phospholipids, diacylglycerols, and triacylglycerols have been identified in the investigated strain. This study allowed pointing out the potential of strain CP30 as a promising bacterioruberin producer, representing an interesting natural carotenoids source to be further investigated as suitable candidate for feed and food application. Comparison of key protein sequences involved in bacterioruberin biosynthesis of CP30 and A. bussei showed sequence similarities of >90%.