Response of the Intracellular Adenosine Triphosphate Pool of Saccharomyces cerevisiae to Growth Inhibition Induced by Excess l -Methionine

Abstract

Yeast cells accumulate S-adenosyl-L-methionine (S-AM) when cultivated in the presence of L-methionine. Cell growth is inhibited by the addition of high concentrations of L-methionine. A number of investigators have attributed this to the depletion of adenosine triphosphate (ATP) as a consequence of the utilization of that mucleotide for S-AM formation. The cellular ATP pool of Saccharomyces cerevisiae was measured during growth inhibition caused by addition of excess L-methionine. Polyethylenimine thin-layer chromatography and subsequent autoradiography were used to quantitate the extracted ATP. Addition of L-methionine to a level of 5 mg/ml in a culture during exponential growth caused an increase in the doubling time of 40 to 50%. During this period, the cellular ATP level continued increasing normally and, as the cells entered stationary growth, receded to a level characteristic of an uninhibited stationary culture growth. After the addition of methionine, there was never an observed depletion of the ATP pool other than the normal fluctuation which occurs in an uninhibited culture. We have concluded that growth inhibition by excessive methionine does not result from limiting availability of ATP.

Pattern of ribonucleic acid synthesis during germination of Allomyces macrogynus mitospores

“…The average determined value was 1,025 ,umol per 106 cells or 16.5 ,imol/g (dry weight) ( Table 2). This amount is comparable to the ATP level in mycelia of N. crassa of 12.8 ,imol/g (dry weight) (5,27) or a value of 200 to 1,000 ,umol per 106 cells determined for Saccharomyces cerevisiae (1). The constancy of the ATP pool size in Allomyces sp.…”

Co‐utilization of amino acid‐rich wastes and glycerol for microbial lipid production

“…The yeast accumulated high amount of lipid per cell dry weight, but the fair cell mass indicated that the initial AA concentrations used in the media were rather high, which might have created a stressful environment that impeded cellular performance. 42 Similar phenomena were observed using AA blends similar to FMAA, with a lipid productivity of 0.75 g L -1 day -1 . The cell mass, lipid, and lipid content were 7.5 g L -1 , 3.4 g L -1 , and 45.1%, respectively (Fig.…”

“…1). We previously demonstrated successful lipid production with AA blends matching a similar AA compositional profile to sheep viscera AA (SVAA), 35 fish muscle AA (FMAA), 36 or meat industry by-product AA (MIAA), 37 as carbon substrates; 23,24 however, it was found that AA in high concentrations had adverse effects on cell viability and lipid production, which might have been due to the high osmotic stress, high intracellular AA level, 42 accumulation of ammonia or inhibitory metabolic intermediates, 43,44 or the very low C/N ratio of the media, as the C/N ratio of about 100 was found to be favorable for lipid production. 21,22 To improve the C/N ratio of the media and subsequently encourage microbial lipid production on AA, 20 g L -1 glycerol was supplied to the media containing the designated AA blends with similar AA compositions to SVAA, FMAA, and MIAA, respectively (Table 1).…”

“…High amounts of AA have known inhibitory effects on yeast. 42 Following the AA and glycerol consumption, it was found that the yeast preferred AA consumption over glycerol. A total of 27.6 g L -1 AA was consumed, which accounted for 57.6% of the total SVAA initially used in the media, whereas the glycerol consumption was 9.8 g L -1 making it 48.9% of the total glycerol used in the media, suggesting that the yeast preference towards AA was comparatively high than glycerol.…”

Nucleotide pools and regulation of ribonucleic acid synthesis in yeast

“…121, 1975 mCi/mmol). After radioactivity had been incorporated for one to two generations, samples were collected and analyzed for nucleotide pools by thinlayer chromatography (2,6,7). Nucleoside triphosphates were localized by ultraviolet absorption and autoradiography.…”