Fatty acid compositions of phospholipids from Selenomonas ruminantium cells, a strictly anaerobic bacterium that requires a volatile fatty acid for normal growth in a glucose medium, were examined. Under fatty acid- deficient conditions, the cells appear to utilize propionate, a normal fermentation product from glucose, as a precursor of odd-numbered long-chain fatty acid moieties of phospholipids. When labeled 1-14C-butyrate or 1-14C- caproate was supplemented to the growth medium, even-numbered fatty acids in phospholipids were all radioactive. The odd-numbered acids, however, carried no significant radioactivity. When cells were grown with 1-14C-valerate, labeled odd-numbered and unlabeled even-numbered fatty acids were detected as components of phospholipids. This phenomenon appears to be due at least in part to the occurrence of α-oxidation of added volatile fatty acids, since imidazole, which is known to be an inhibitor of α-oxidation, inhibited the formation of even-numbered long-chain fatty acids in cells grown in valerate and heptanoate. Imidazole at 30mM did not inhibit cell growth with even-numbered fatty acids (C4 and C8), but growth with odd-numbered fatty acids (C5 and C7) was inhibited significantly. The growth inhibition by imidazole was partially released by the addition of a very small amount of butyrate or caproate. It was concluded that even-numbered fatty acids are important constituents of phospholipids for normal growth of this organism.
According to Bergey's Manual of Determinative Bacteriology, 7th edition, the genus Arthrobacter is divided into two groups, one of which utilizes citrate as a sole organic nutrient and the other does not utilize citrate. Among authentic strains of this genus, the growth of Arthrobacter pascens IFO 12139 and Arthrobacter simplex IFO 12069 was inhibited by citrate. It was found that A. pascens IFO 12139 required bivalent cation(s) for growth and failed to grow when the medium contained excess of citrate against bivalent cations. On the other hand, A. simplex IFO 12069 could not utilize citrate as a sole source of carbon, and citrate inhibited glucose utilization of the organism. Among many strains belonging to the genera Corynebacterium, Brevibacterium, and Bacillus, growth was inhibited by citrate.
The electric conductance of black lipid membranes in aqueous phases was analyzed on the basis of a protonic conduction scheme by assuming a simple model for the dissociation states of dipolar molecules in the membrane. There appear to be three ways of conduction resulting in this membrane conductance; i.e., the proton conduction via negatively or dipolar charged sites and the hydroxyl ion conduction via positively charged sites. The present scheme of protonic conduction can well explain the conductance behavior of the membranes and it is supported by the fact that the membranes showed potential difference in the theoretical magnitude when subjected to a pH gradient. The potential difference shows, however, anomalous characteristics around pH 5, where the membranes seem to take a composite structure due to the applied pH difference, one-half of the membranes being a proton conductor and the other half a negative hole conductor. The activation energy of the membrane conductance is also discussed in this connection over a wide range of pH.
Phycomyces blakesleeanus contains 26-28g free lipids per 100g dry mat. The lipid material is composed of phospholipids, sterols (mainly ergosterol), diglycerides, triglycerides, waxes, free fatty acids, and carotenes. It was possible to identify the presence of phosphatidylserine, sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, phosphatidic acid, and cardiolipin in the phospholipid fraction. The fatty acid composition of free lipids was determined by gas-liquid chromatography. Trace amounts of C17 fatty acids were detected. Small amount of arachidonic acid was identified. Oleic, linoleic, linolenic, stearic, and palmitic were the major fatty acids present in the free lipids of P. blakesleeanus.
The DNA base composition (GC content) of 53 cultures of Pichia and supposed related yeasts, which represented 35 species and a variety, was investigated. The GC content of Pichia ranged from 28.3 to 50.2%, and intrageneric variation was about 22%. Any prominent subgroups could not be detected within the genus and this genus was supposed to be very heterogeneous from the taxonomic points of view.
A pyocinogenic factor responsible for the production of pyocin R2, a bacteriocin which resembles a phage tail, was suggested to be located on the chromosome of Pseudomonas aeruginosa. By conjugation experiments employing pyocin-less strains as recipients, the pyocin locus was found to be linked to a tryptophan marker. A pyocin-less character could also be transmitted from a male to a pyocin-positive female strain. A tentative map of the Pseudomonas chromosome including pyocin R2 as well as other markers was presented.
A pyocinogenic factor responsible for the production of pyocin R2 was analyzed by transduction with phage F116. The pyocin factor could be transferred linked to a tryptophan marker. The pyocin-less character could also be transduced. It is concluded that the pyocinogenic factor is incorporated into the bacterial chromosome close to a str-trp-1 region. The relationship between pyocins and bacteriophages is discussed.