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Capnocytophaga spp. contain a group of unusual sulfonolipids, called capnoids (W. Godchaux III and E. R. Leadbetter, J. Bacteriol. 144:592-602, 1980). One of these lipids, capnine, is 2-amino-3-hydroxy-15-methylhexadecane-1-sulfonic acid; the others are, apparently, N-acylated versions of capnine. The lipids were found, in amounts ranging from 2.5 to 16 mumol of capnoid sulfur per g of cells (wet weight), in two Cytophaga spp. and also in several closely related organisms: several Capnocytophaga spp., Sporocytophaga myxococcoides, two Flexibacter spp., and two Flavobacterium spp. With the exception of the flavobacteria, all of these bacteria have been shown to exhibit gliding motility. The two Flavobacterium spp. belong to a subset of that genus that shares many other characteristics with the cytophagas. Only the Capnocytophaga spp. contained large quantities of capnine as such; in all of the others, most (and possibly all) of the capnoids were present as N-acylcapnines. Capnoid-negative bacteria included some gliding organisms that may not be closely related to the cytophagas: two fruiting myxobacters, a gliding cyanobacterium (Plectonema sp.), Beggiatoa alba, Vitreoscilla stercoraria, Herpetosiphon aurantiacus, and Lysobacter enzymogenes. Nongliding bacteria representing nine genera were also tested, and all of these fell into the capnoid-negative group.

A group of unusual sulfonolipids was found in bacteria of the genus Capnocytophaga. One of these lipids, to which we have assigned the trivial name capnine, was isolated in 98% pure form and was identified, by infrared absorption spectrometry, high-resolution mass spectrometry, and other methods, as 2-amino-3-hydroxy-15-methylhexadecane-1-sulfonic acid. Another lipid appears to be an N-acylated version of capnine; after acid hydrolysis, its sulfur was recovered in a form chromatographically indistinguishable from that of capnine. The new lipids are related structurally to sphingosine and the ceramides, respectively, but differ markedly from those compounds in important respects, notably the presence of the sulfonate group. Some Capnocytophaga strains accumulated mostly capnine, whereas others accumulated mostly N-acylcapnine. All seven strains examined were found to contain the new lipids, in amounts ranging from 7 to 16 mumol/g of cells (wet weight). The lipids were found in isolated cell envelopes, where they were present in amounts ranging up to 400 mg/g of envelope protein; they are, accordingly, major cell components.

The gram-negative gliding bacterium Cytophaga johnsonae contains not only large quantities of unusual sulfonolipids but also, as we report here, a second class of unusual lipids. These lipids were detected and quantified by two-dimensional thin-layer chromatography of lipids from cells grown in the presence of [14C]acetate and shown by chemical studies to be alpha-N-(3-fatty acyloxy fatty acyl)ornithines. Like the sulfonolipids, these ornithine lipids were localized in the outer membrane (whereas phosphatidylethanolamine was the predominant lipid of the inner membrane). In a sulfonolipid-deficient mutant, the missing lipid was replaced, specifically, by an increased amount of ornithine lipid. Cells grown in liquid media contained predominantly ornithine lipids with nonhydroxylated residues in the O-fatty acyl position. In contrast, surface-grown cells contained a high proportion of ornithine lipids in which the O-fatty acyl group was 3-hydroxylated. The sulfonolipids and ornithine lipids are apparently coregulated in the sense that, regardless of perturbations caused by mutation or growth conditions, their total amounts remain constant at 40% of total cell lipid.