The isoprenoid compounds in gram-negative methanol-, methane-, and methylamine-utilizing bacteria were investigated. All strains tested contained ubiquinone, but none contained menaquinone. The ubiquinone types were Q-8, Q-9, or Q-10. The so-called obligate methylotrophs and methanotrophs (genus
Methylobacillus, Methylophaga, Methylomonas,
Methylococcus, and
Methylovibrio) contained ubiquinone Q-8. The
Hyphomicrobium strains contained Q-9. The other facultative methylotrophs and methylamine-utilizing bacteria contained Q-10. A large amount of squalene occurred in the
Methylobacillus, Methylophaga, Methylomonas, and
Methylococcus strains which utilize one-carbon compounds via the ribulose monophosphate pathway. The
Protomonas extorquens and
Methylobacterium organophilum strains contained a large amount of sterols (Hop-22(29)-ene and Hopan-22-ol), carotenoid pigments, and a small amount of squalene. The
Hyphomicrobium strains contained a small amount of squalene and Hop-22(29)-ene. The
Xanthobacter strains contained a large amount of carotenoid pigments (zeaxanthin, zeaxanthin monorhamnoside, and zeaxanthin dirhamnoside). The
Protomonas and
Methylobacterium strains were unique in the existence of sterols and large amounts of total isoprenoid compounds, 4.68 to 7.97mg/g of dry cell. The distribution of squalene, sterols, quinones, and carotenoid pigments conforms with the morphological, physiological, and other chemo- taxonomic characteristics in gram-negative methanol-, methane-, and methylamine-utilizing bacteria.
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