Effect of glycine on the metabolism of phospholipid in Bacillus subtilis 6169 was studied. Cell lysis and an alteration of phospholipid metabolism were observed when the cells were grown in the presence of 1% of glycine. Under these conditions, cardiolipin content increased from 20 to 60% with concomitant decrease in phosphatidylglycerol from 60 to 15% of the total phospholipid-phosphorus. The incorporation of 32P-orthophosphate and 3H-glycerol into phospholipids also showed that glycine did not inhibit the synthesis of phosphatidylglycerol but presumably stimulated the conversion of phosphatidylglycerol to cardiolipin. Addition of a small amount of glycerol with glycine to the culture medium significantly suppressed the cell lysis and the change in the phospholipid metabolism. The possible mechanism, by which phospholipid metabolism was altered, was discussed.
Freeze-dried Bacillus megaterium IAM 1166 spores humidified with water vapor to a water content of above 30% germinated spontaneously without the addition of any germinant. Differential scanning calorimetric thermogram of the spores thus germinated had absorption peaks at about 100° and 130° other than a large peak due to the evaporation of spore water. Both 100° and 130° peaks were characteristic of spores germinating spontaneously by water vapor and corresponded to those in the standard Ca-DPA precipitate deposited at room temperature. The reflection spectra of germinated spores also agreed with those of the standard Ca-DPA. Since the weight decrease in thermogravi-metric analysis, the water content by the Karl Fischer method, and the elementary analysis of the standard Ca-DPA showed that 1mol of Ca-DPA was bound by 1.5mol of H2O, it was concluded that 1mol of Ca-DPA in germinated spores was hydrated by 1.5mol of H2O. It is also suggested that the macromolecule-Ca-DPA complex in dormant spores might be transformed into a free state of Ca-DPA hydrate by water vapor, produces more Ca-DPA hydrate molecules autocatalytically, and thus triggers the spontaneous germination by setting free more and more functional macromolecules.
From Escherichia coil CS101, mutants with temperature-sensitive formation of phosphatidylethanolamine (PE) have been isolated by a combination of 3H suicide concentration from the mutagenized cells which incorporated L-serine[3-3H] and a survey of phospholipid synthesis by a direct ion-exchange paper chromatography. Among 306 temperature-sensitive growth mutants, 38 strains were found defective in optimal formation of PE at 42°. Changes in lipid synthesis in these mutants accompanied by abnormalities of growth and morphology have been described. Among them, OS294, the most thermosensitive in PE formation, was further characterized. Upon temperature shift from 27° to 42° of this strain, the formation of PE stopped almost immediately and completely, while that of phosphatidylglycerol (PG) continued and that of cardiolipin (CL) was significantly stimulated. The usefulness of these mutants defective in single lipid synthesis for understanding the possible roles played by individual lipids in cell physiology has been discussed.
Galacturonic acid, and oligo- and poly-galacturonic acids induced the synthesis of endopolygalacturonase, exopolygalacturonase, pectinesterase, and enzymes responsible for galacturonic acid metabolism in astrain of Acrocylindrium. These enzymes had similar characteristics for inducer specificity, time curves of induction, and catabolite repression. In the absence of inducers, mutants constitutive for exopolygalacturonase failed to synthesize endopolygalacturonase, pectinesterase, and enzymes responsible for galacturonic acid metabolism. However, the rate of the induced synthesis on galacturonic acid of endopolygalacturonase and pectinesterase in mutants was much faster than that in the wild-type strain. A relationship between the induced synthesis of these enzymes was discussed.
Lipid composition of Saccharomyces cerevisiae defective in mitochondria and respiratory activity due to pantothenic acid deficiency and its normalization were studied. Quantitatively, the deficient cells contained about one-half of total lipid, one-fifth of fatty acids, one-fourth of ergosterol, and one-half of phospholipids compared with normal cells. Unsaturated fatty acids, such as palmitoleic acid and oleic acid, were decreased in the deficient cells. The composition of fatty acids and phospholipids in mitochondria in both types of cells was the same as in whole cells. Phospholipids, such as phosphatidylethanolamine and glycerol phosphatides, decreased in deficient cells, but the percentage of phosphatidyl-choline increased. Intracellular coenzyme A content was one-fifth of the normal. By the addition of pantothenic acid to the deficient cells, unsaturated fatty acids, especially palmitoleic acid, were synthesized, but other fatty acids were synthesized to only a small extent. The recovery of phospholipids preceded that of fatty acids. Along with the recovery of these lipids, the respiration rate of the deficient cells also reached the normal level.
The respiratory-deficient mutant H7, obtained by Beljanski from Monod's strain of Escherichia coil, differs in several respects from the parent strain. Comparison of the DNAs from the two cultures has revealed complete homology. Physiologically, the mutant resembles the homofermentative lactobacilli; it does not contain catalase or cytochromes, grows better in the absence than in the presence of air, produces lactic acid from glucose even under aerobic conditions, and requires amino acids for growth. These properties are discussed in relation to the respiratory deficiency, as is their bearing on the evolutionary status of the lactobacilli.
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