Identification of the wild type bacterium Paracoccus sp. LL1 as a promising β-carotene cell factory

Carotenoids are biomolecules naturally produced as secondary metabolites. The scientific interest in microbial carotenoids production is gaining more attraction because of their economic sustainability and cost-effectiveness. This study aimed to define the Paracoccus sp. LL1 carotenoids and fatty acids quali-quantitative profiles under controlled fermentation processes carried out at two different temperatures. Moreover, the whole genome of the selected strain LL1 has been sequenced and analyzed, allowing us to identify the gene clusters involved in carotenoid biosynthesis. The fatty acid profile detected and the genome sequencing allowed to rename the strain investigated Paracoccus marcusii strain LL1. Stearic and vaccenic fatty acids have been detected in the highest percentage as the main cellular membrane fatty acids characteristic of the strain investigated. Whereas, twelve different carotenoids produced by the bacterium investigated have been identified. Among these the most produced was β-carotene, which reached up a final concentration of 0.35 ± 0.01 mg g−1 of dry biomass. Furthermore, Paracoccus sp. LL1 biomass extract was investigated for antibacterial activity against selected strains. This study allowed pointing out the great potential of the wild type bacterium Paracoccus marcusii strain LL1 as a promising β-carotene producer, representing an interesting alternative for natural carotenoids production.