1. The occurrence of a novel series of triterpenoid carotenes in Streptococcus faecium UNH 564P is reported. 2. This series, which comprises the C30 analogues of phytoene, phytofluene, ζ-carotene, 7,8,11,12-tetrahydrolycopene and neurosporene, appears to be analogous to the C40 Porter–Lincoln series and a pathway of triterpenoid carotene dehydrogenation is proposed to account for the formation of these compounds. 3. Two cis isomers of the C30 analogue of neurosporene are described. 4. An appropriate system of nomenclature for these novel compounds is proposed.
