Identification and the developmental formation of carotenoid pigments in the yellow/orange Bacillus spore-formers

Spore-forming Bacillus species capable of synthesising carotenoid pigments have recently been isolated. To date the detailed characterisation of these carotenoids and their formation has not been described. In the present article biochemical analysis on the carotenoids responsible for the yellow/orange pigmentation present in Bacilli has been carried out and the identity of the carotenoids present was elucidated. Chromatographic, UV/Vis and Mass Spectral (MS) data have revealed the exclusive presence of a C30 carotenoid biosynthetic pathway in Bacillus species. Apophytoene was detected representing the first genuine carotenoid formed by this pathway. Cultivation in the presence of diphenylamine (DPA), a known inhibitor of pathway desaturation resulted in the accumulation of apophytoene along with other intermediates of desaturation (e.g. apophytofluene and apo-ζ-carotene). The most abundant carotenoids present in the Bacillus species were oxygenated derivatives of apolycopene, which have either undergone glycosylation and/or esterification. The presence of fatty acid moieties (C9 to C15) attached to the sugar residue via an ester linkage was revealed by saponification and MS/MS analysis. In source fragmentation showed the presence of a hexose sugar associated with apolycopene derivatives. The most abundant apocarotenoids determined were glycosyl-apolycopene and glycosyl-4′-methyl-apolycopenoate esters. Analysis of these carotenoids over the developmental formation of spores revealed that 5-glycosyl-4′-methyl-apolycopenoate was related to sporulation. Potential biosynthetic pathways for the formation of these apocarotenoids in vegetative cells and spores have been reconstructed from intermediates and end-products were elucidated.

Identification and the developmental formation of carotenoid pigments in the yellow/orange Bacillus spore-formers. Laura Perez-Fons, Sabine Steiger, Reena Khaneja, Simon M. Cutting, Gerhard Sandmann and Paul D. Fraser.Figure optionsDownload high-quality image (218 K)Download as PowerPoint slideResearch Highlights
► Pigmented Bacillus species are capable of forming apocarotenoids
► The apocarotenoids formed in Bacillus are complex undergoing derivatisation with sugar and fatty acid groups.
► The apocarotenoid pathway in the Bacillus species is inhibited by the presence of diphenylamine (DPA).
► The predominant apocarotenoids in these Bacillus species are glycosyl-apolycopene and glycosyl-4′-methyl-apolycopenoate.
► Developmental analysis revealed that 5-glycosyl-4′-methyl-apolycopenoate was related to sporulation.