Teijiro Kamihara

Morphological chance in Candida tropicalis pK 233 caused by ethanol and its prevention by myo-inositol

The cells of Candida tropicalis pK 233 grew in filamentous form when cultivated in a synthetic medium supplemented with ethanol. The ethanol-grown cells excreted significant amounts of polysaccharides into culture medium. Myo-inositol added simultaneously with ethanol prevented both the morphological change and the extracellular production of polysaccharides.

Diverse effects of formate on the dissimilatory metabolism of nitrate in Pseudomonas denitrificans ATCC 13867: Growth, nitrite accumulation in culture, cellular activities of nitrate and nitrite reductases

The growth of Pseudomonas denitrificans ATCC 13867 under denitrifying conditions was significantly stimulated by adding an appropriate amount of formate (2.5 mM or above) to the growth medium. The accumulation of nitrite in the culture was markedly depressed so long as formate remained in the culture above a certain level. Cellular activities of enzymes participating in denitrification also changed. The cells grown in the presence of formate exhibited a lower nitrate reductase activity and, in contrast, a higher nitrite reductase activity than the cells grown without added formate.

Effects of thiamine and pyridoxine on the content and composition of sterols in Saccharomyces carlsbergensis 4228

Abstract The level of sterols in S. carlsbergensis 4228 cells grown aerobically on a synthetic medium fortified with thiamine was significantly low compared with that in the control cells. The levels of free and esterified sterols in the thiamine-cells were 60% and 10% of the corresponding sterol levels in the control cells, respectively. Analysis by gas-liquid chromatography of non-saponifiable lipids extracted from the cells revealed that the amounts of squalene, lanosterol and two unidentified sterols were higher than those in the control cells and that ergosterol and zymosterol, major sterols in the control cells, were not present. These effects of thiamine on the content and composition of sterols were abolished by the addition of pyridoxine to the medium.

Enhanced metabolism of phosphatidylinositol in Candida tropicalis in association with filamentous growth caused by ethanol

Candida tropicalis Pk 233 grows in filamentous form in ethanol‐supplemented medium, and myo‐inositol prevents the ethanol ettect [(1979) Bioch!em. Biophys. Res. Commun. 91, 351–355]. Cells, which were grown with ethanol to the log phase, exhibited an increased rate of phosphatidylinositol turnover as judged by pulse‐chase experiments with 32Pi. Such enhanced metabolism of phosphatidylinositol was not observed in fully developed filamentous cells at the stationary phase or in yeast‐like cells which were grown without added ethanol or with ethanol plus myo‐inositol. The metabolism of other phospholipids was not affected by ethanol.

Accumulation of cAMP in the cells of Candidatropicalis at an early stage of ethanol-induced filamentous growth and its prevention by myo-inositol

Phosphatidylinositol metabolism is enhanced in the cells of Candida tropicalis Pk 233 at an early stage of filamentous growth caused by ethanol, and myo-inositol prevents the ethanol-induced changes in the metabolism and morphology [Uejima et al. (1987) FEBS Lett. 214, 127-129]. The accumulation of cAMP and an increase in adenylate cyclase activity were observed in the cells grown with ethanol to the mid-log phase. Myo-inositol abolished these effects of ethanol also. The activity of cAMP phosphodiesterase was affected by neither ethanol nor myo-inositol. These results suggest that the inositol phospholipid-linked and cAMP-linked signaling pathways may be involved in the mechanism of ethanol-induced filamentous growth of this yeast and also that myo-inositol would affect morphogenesis by controlling these pathways.

Respiratory deficiency in Saccharomyces carlsbergensis 4228 caused by thiamine and its prevention by pyridoxine.

Summary The cells of Saccharomyces carlsbergensis 4228 (ATCC 9080), growing at a limited rate after a long lag period in the presence of thiamine and absence of pyridoxine, exhibited a markedly low respiration rate, despite the fact that the cultivation was carried out under aerobic conditions. The cytochrome oxidase activity of the cells was also negligible. The characteristic spectra of cytochrome pigments were not detected. Addition of pyridoxine to the medium prevented the growth inhibition and eliminated these effects of thiamine.

Nitrite reduction with formate in Pseudomonas denitrificans ATCC 13867

Abstract Formate served as an electron donor in dissimilatory nitrite reduction in resting cells of a denitrifier, Pseudomonas denitrificans . Pyruvate also donated electrons to nitrite. Pyruvate reduced nitrite at the same rate as formate after some lag period. Citrate, the carbon source for cultivation medium employed in this study, was less effective for nitrite reduction. Two distinct cytochromes were shown to be involved in the electron transfer from formate to nitrite.

Effects of thiamine and pyridoxine on the composition of fatty acids in Saccharomyces carlsbergensis 4228

Summary The cells of Saccharomyces carlsbergensis 4228 growing aerobically in the presence of thiamine and absence of pyridoxine, which were in a deficient state of respiratory activity, showed a marked decrease in the content of unsaturated fatty acids. Addition of pyridoxine to the medium prevented completely this effect of thiamine as observed in the case of respiratory activity.

Effects of thiamine and pyridoxine on the lipid composition of Saccharomyces carlsbergensis 4228.

The lipid composition of Saccharomyces carlsbergensis 4228 cells grown aerobically in the presence of thiamine and absence of pyridoxine was markedly different from that of cells grown without addition of both of the growth factors. In addition to the previous observations showing a reduction in the levels of unsaturated fatty acids (Nishikawa, Y., Nakamura, I., Kamihara, T. and Fukui, S. (1974) Biochem. Biophys. Res. Commun. 59, 777-780) and lack of zymosterol and ergosterol (Nagai, J., Katsuki, H., Nishikawa, Y., Nakamura, I., Kamihara, T. and Fukui, S. (1974) Biochem. Biophys. Res. Commun. 60, 555-560), the thiamine-grown cells were found to contain low levels of total lipids, sterols (especially in the form of esters), triacylglycerols and total phospholipids. However, relative contents of triacylglycerols and phospholipids to total lipids were higher than those of control cells. Hydrocarbons and diacylglycerols accumulated to appreciable degrees. Phospholipid composition was also influenced by thiamine. The ratio of phosphatidylinositol to total phospholipids increased, whereas that of phosphatidylethanolamine decreased. The levels of phosphatidylcholine plus phosphatidylserine decreased in a similar ratio to that of total phospholipids. It was found that unsaturated fatty acid contents were low in all lipid esters tested. The effect of thiamine was particularly noteworthy in the case of sterol esters. Concomitant addition of pyridoxine with thiamine to the medium brought about a normal lipid composition in the yeast cells.

Mutants of Streptococcus faecalis concerning pyruvate dehydrogenation

The conversion of pyruvate into acetyl-CoA or acetate is recognized to comprise several separate pathways in bacteria. Escherichia coli has three pathways; pyruvate dehydrogenation complex (PDH) [EC 1.2.4.1), pyruvate oxidase [EC 1.2.2.21 and pyruvate formate-lyase (PFL). In Streptococcus faecalis, PDH is widely accepted to mediate the breakdown of pyruvate to acetyl-CoA [l-3] . PFL is also suggested to occur in this organism under certain conditions on the basis of formate accumulation in the culture [4-71. Lindemark et al. [S] purified extensively a pyruvate-formate exchange system from this organism, which was believed to be related closely with PFL. In addition, we obtained data suggesting the existence of a lipoic acid-independent pyruvate dehydrogenating system in the cells grown in the presence of ascorbic acid or FeS04 [9]. The physiological significance of the existence of these separate pathways for pyruvate dehydrogenation remains obscure. Mutants may provide a useful tool for clarifying this problem. This communication deals with the isolation of mutants of S. faecalis concerning pyruvate dehydrogenation. Partial characterization of the ascorbic acid-induced system and the occurrence of PFL activity are also described.