Radiorespirometry of Candida utilis in phased culture under nitrogen-, carbon-, and phosphorus-limited growth

1977 ◽  
Vol 23 (12) ◽  
pp. 1689-1694 ◽  
Author(s):  
P. S. S. Dawson ◽  
L. P. Steinhauer
Keyword(s):  
Metabolic Activity ◽  
Critical Points ◽  
Candida Utilis ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Hexose Monophosphate ◽  
Limited Growth ◽  
Hexose Monophosphate Pathway

The release of 14CO2 from specifically labelled glucose ([G-1-14C], [G-2-14C], [G-3,4-14C], and [G-6-14C]) by phased cells of C. utilis was examined at intervals during 6-h cycles under conditions of N-, P-, and C-limited growth.On the basis that the release of 14CO2 from [G-1-C14] could serve as a measure of hexose monophosphate pathway (HMP) activity, of 14CO2 from [G-3,4-14C] as a measure of Embden–Meyerhof–Parnas (EMP) activity, and 14CO2 from [G-6-14C] as indicative of tricarboxylic acid (TCA) cycle activity, it was concluded that a relatively uniform operation of EMP occurred throughout the cycle in N-, P-, and C-limited cells, and of HMP and TCA in C-limited cells, but considerable variations took place in HMP and TCA cycle activities in N- and P-limited cells. The patterns of 14CO2 released from [G-2-14C] were more closely related to those observed from[G-1-14C] and [G-3,4-14C] than from [G-6-14C].Changes in the rate of 14CO2 evolution during the cycle were sometimes abrupt and likely coincided with 'critical points' of metabolic activity in the cycle.

Relationship between iron-limited growth and energy limitation during phased cultivation of Candida utilis

1978 ◽  
Vol 24 (4) ◽  
pp. 440-447 ◽  
Author(s):  
K. C. Thomas ◽  
P. S. S. Dawson
Keyword(s):  
Ethyl Acetate ◽  
Candida Utilis ◽  
Energy Charge ◽  
Tca Cycle ◽  
Iron Limitation ◽  
Limited Growth ◽  
Acetyl Coa ◽  
Limiting Nutrient ◽  
Energy Limitation

The yeast Candida utilis was continuously synchronized by the phasing technique (6 h doubling time) with either iron or nitrogen as the limiting nutrient. Iron limitation resulted in decreased molar growth yields with respect to the carbon substrates and ammonia and in increased specific rates of oxygen uptake. Relatively low energy-charge values were maintained by the iron-limited culture. All these taken together seemed to indicate that the growth of the yeast under iron limitation was also limited by metabolically available energy.Considerable amounts of ethyl acetate were produced by the yeast under phased cultivation when the growth was limited by iron but not by nitrogen. In vitro studies using cell-free extracts showed that the substrates for ethyl acetate synthesis were acetyl coenzyme A (acetyl CoA) and ethanol. Under iron-limited growth acetyl CoA seemed to be diverted to ethyl acetate formation rather than being oxidized through the tricarboxylic acid (TCA) cycle. The possibility of energy limitation under iron-limited growth being brought about by the reduced capacity of the yeast to oxidize acetyl CoA through the TCA cycle is considered.

scholarly journals Effect of dithiocyano-methane on hexose monophosphate pathway in the respiratory metabolism of Escherichia coli

AMB Express ◽  
2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yanfeng Chen ◽  
Wenjie Ke ◽  
Huabin Qin ◽  
Siwei Chen ◽  
Limei Qin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Control Group ◽  
Respiratory Metabolism ◽  
Hexose Monophosphate ◽  
Hexose Monophosphate Pathway ◽  
Response To Stress ◽  
Glucose Decomposition ◽  
Decomposition Pathway ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract This paper studied the inhibitory effects of dithiocyano-methane (DM) on the glucose decomposition pathway in the respiratory metabolism of Escherichia coli. We investigated the effects of DM on the activities of key enzymes (ATPase and glucose-6-phosphate dehydrogenase, G6PDH), the levels of key product (nicotinamide adenosine denucleotide hydro-phosphoric acid, NADPH), and gene expression in the hexose monophosphate pathway (HMP). The results showed that the minimum inhibitory concentration (MIC) and the minimum bactericide concentration (MBC) of DM against the tested strains were 5.86 mg/L and 11.72 mg/L, respectively. Bacteria exposed to DM at MIC demonstrated an increase in bacterial ATPase and G6PDH activities, NADPH levels, and gene expression in the HMP pathway compared to bacteria in the control group, which could be interpreted as a behavioral response to stress introduced by DM. However, DM at a lethal concentration of 10 × MIC affected glucose decomposition by inhibiting mainly the HMP pathway in E. coli.

The influence of temperature on the pathways of glucose catabolism in Pseudomonas fluorescens

1969 ◽  
Vol 15 (9) ◽  
pp. 995-1000 ◽  
Author(s):  
S. A. Palumbo ◽  
Lloyd D. Witter
Keyword(s):  
Continuous Culture ◽  
Pseudomonas Fluorescens ◽  
Enzyme Activities ◽  
Hexose Monophosphate ◽  
Influence Of Temperature ◽  
Glucose Catabolism ◽  
Hexose Monophosphate Pathway ◽  
Influence Of Temperature On ◽  
Major Shift

The influence of temperature on the pathways of glucose catabolism in Pseudomonas fluorescens has been investigated using the radiorespirometry method. When grown in continuous culture with limiting concentrations of glucose, the organism metabolized 86% of the glucose via the Entner–Doudoroff pathway at 30, 20, and 8 C. The remaining glucose, 14%, was metabolized via the hexose monophosphate pathway. When the organism was grown on non-limiting concentrations of glucose at 8 C, a major shift in pathways of glucose catabolism was observed. Fifty-seven percent of the glucose was degraded via the hexose monophosphate pathway and only 43% via the Entner–Doudoroff pathway. A change in temperature altered the pathways of glucose catabolism by regulating the growth limiting concentration of glucose rather than by directly affecting the respective enzyme activities of the pathways.

scholarly journals Biochemical elucidation of citrate accumulation in Synechocystis sp. PCC 6803 via kinetic analysis of aconitase

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maki Nishii ◽  
Shoki Ito ◽  
Noriaki Katayama ◽  
Takashi Osanai
Keyword(s):  
Kinetic Analysis ◽  
Chemical Equilibrium ◽  
Isocitrate Dehydrogenase ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Unicellular Cyanobacterium ◽  
Citrate Accumulation ◽  
Kinetics Of ◽  
Synechocystis Sp ◽  
Pcc 6803

AbstractA unicellular cyanobacterium Synechocystis sp. PCC 6803 possesses a unique tricarboxylic acid (TCA) cycle, wherein the intracellular citrate levels are approximately 1.5–10 times higher than the levels of other TCA cycle metabolite. Aconitase catalyses the reversible isomerisation of citrate and isocitrate. Herein, we biochemically analysed Synechocystis sp. PCC 6803 aconitase (SyAcnB), using citrate and isocitrate as the substrates. We observed that the activity of SyAcnB for citrate was highest at pH 7.7 and 45 °C and for isocitrate at pH 8.0 and 53 °C. The Km value of SyAcnB for citrate was higher than that for isocitrate under the same conditions. The Km value of SyAcnB for isocitrate was 3.6-fold higher than the reported Km values of isocitrate dehydrogenase for isocitrate. Therefore, we suggest that citrate accumulation depends on the enzyme kinetics of SyAcnB, and 2-oxoglutarate production depends on the chemical equilibrium in this cyanobacterium.

scholarly journals HISTOCHEMICAL INVESTIGATIONS ON THE IN VIVO EFFECTS OF FLUORIDE ON TRICARBOXYLIC ACID CYCLE DEHYDROGENASES FROM PELARGONIUM ZONALE: PART II

1967 ◽  
Vol 15 (4) ◽  
pp. 202-206
Author(s):  
C. JAMES LOVELACE ◽  
GENE W. MILLER
Keyword(s):  
Sodium Fluoride ◽  
Reductase Activity ◽  
Tricarboxylic Acid Cycle ◽  
Leaf Tissue ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Pelargonium Zonale ◽  
Acid Cycle ◽  
In Vivo Effects

In vivo effects of fluoride on tricarboxylic acid (TCA) cycle dehydrogenase enzymes of Pelargonium zonale were studied using p-nitro blue tetrazoleum chloride. Plants were exposed to 17 ppb HF, and enzyme activities in treated plants were compared to those in controls. Leaves of control plants were incubated in 5 x 10–3 M sodium fluoride. Injuries observed in fumigation and solution experiments were similar. Leaf tissue subjected to HF or sodium fluoride evidenced less succinic p-nitro blue tetrazoleum reductase activity than did control tissue. Other TCA cycle dehydrogenase enzymes were not observably affected by the fluoride concentrations used in these experiments. Excised leaves cultured in 5 x 10–3 M sodium fluoride exhibited less succinic p-nitro blue tetrazoleum reductase activity after 24 hr than did leaves cultured in 5 x 10–3 M sodium chloride.

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