THE MAJOR CAROTENOID IN ALL KNOWN SPECIES OF HELIOBACTERIA IS THE C-30 CAROTENOID 4,4'-DIAPONEUROSPORENE, NOT NEUROSPORENE

The carotenoids of five species of heliobacteria (Heliobacillus mobili s, Heliophilum fasciatum, Heliobacterium ch[or-um, Heliobacterium mode sticaldum, and Heliobacterium gestii) were examined by spectroscopic m ethods, and the C-30 carotene 4,4'-diaponeurosporene was found to be t he dominant pigment; heliobacteria were previously thought to contain the C-40 carotenoid neurosporene. In addition, trace amounts of the C- 30 diapocarotenes diapolycopene, diapo-zeta-carotene, diapophytofluene , and diapophytoene were also found. Up to now, diapocarotenes have be en found in only three species of chemoorganotrophic bacteria, but not in phototropic organisms. Furthermore, the esterifying alcohol of bac teriochlorophyll g from all known species of heliobacteria was determi ned to be farnesol (C-15) instead of the usual phytol (C-20) Heliobact eria may be unable to produce geranylgeranyol (C-20).