Respiratory quotients

RQ is the molar ratio of CO., that evolves from the consumed O2 during fermentation and can be defined as follows [5, 6]. 

If an aerobic metabolism is dominant in a fermentor, the RQ value becomes 1.0 according to the following chemical equation. 

However, if an anaerobic metabolism such as ethanol fermentation occurs in a fermentor in the presence of high concentration of glucose, the RQ value becomes larger than 1.0, known as the Crabtree effect. This is because CO2 evolves without O2 consumption as follows. 

the RQ value can be used to estimate the metabolic status in an aerobic bioreactor. In practice, the RQ value can be determined based on the analysis of CO2 and O2 in the off-gas from a bioreactor. There may be difficulty in calculating the RQ due to the noise of measured data when the COj content in the off-gas is relatively low compared with the O2 content in the supply of air (20.91%). 

The RQ control, where the sugar-feeding rate is controlled so as to maintain the RQ value at approximately 1.0, is the distinct control method in aerobic fed-batch cultivation such as with baker s yeast production. By keeping the RQ at 1.0 during the fed-batch operation, cell production with a high yield will be achieved. 

Lusk has suggested the following empirical equation for the conversion of palmitic acid to D-glucose. 

The greater the proportion of the total metabolism which is concerned with the change fat — carbohydrate, the more the R. Q. may be expected to be depressed below the fasting non-protein R. Q. of 0.707 which is usually regarded as the minimal normal value. 

Many of the low R. Q. s which have been reported in the literature may be explainable because of inaccuracies in the determination of oxygen. This is particularly true when a closed circuit apparatus is employed, where any leak in the system will result in an abnormally high value for oxygen with a resulting low R. Q. 

Pembrey has found values for the R. Q. of hibernating marmots as low as 0.55 while Voit reported a minimum value of 0.33. In all cases where these values were obtained, the actual quantities of oxygen and carbon dioxide determined were extremely small and it is possible that inaccuracies could be traceable to analytical difficulties. It should be pointed out that most of Pembrey s values for R. Q. s in the hibernating marmots are approximately 0.70 or above. Irregularities in breathing 

If allowance is made for the fact that much of the carbohydrate formed from protein, which is oxidized in the non-diabetic, may escape metabolism by the diabetic and be excreted in the urine, the protein R. Q. for the diabetic should be 0.632 instead of the normal value of 0.802. The R. Q. for fat is also altered because of the failure of a complete combustion of this foodstuff, due to the attendant ketonuria. 

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The respiratory quotient (RQ) is often used to estimate metabolic stoichiometry. Using quasi-steady-state and by definition of RQ, develop a system of two linear equations with two unknowns by solving a matrix under the following conditions the coefficient of the matrix with yeast growth (y = 4.14), ammonia (yN = 0) and glucose (ys = 4.0), where the evolution of C02 and biosynthesis are very small (o- = 0.095). Calculate the stoichiometric coefficient for RQ =1.0 for the above biological processes ... 

For several hours after a meal, while the products of digestion are being absorbed, there is an abundant supply of metabolic fuels. Under these conditions, glucose is the major fuel for oxidation in most tissues this is observed as an increase in the respiratory quotient (the ratio of carbon dioxide produced to oxygen consumed) from about 0.8 in the starved state to near 1 (Table 27-1). 

There are no convincing experimental data, based on respiratory quotients, which support the hypothesis that fatty acids are convertible to sugar. Contrasted with the marked alterations which have been observed when carbohydrate is being changed to fat, the decreases in R. Q. below the level of 0.707 for fat, which should be observed if fat were changing to carbohydrate, are very small and can be partially if not entirely explained by alterations in the R. Q. of the metabolized protein and fat, due to their incomplete, oxidation. 

Data from indirect calorimetry can also be used to determine a respiratory quotient. Values greater than 1 suggest overfeeding, whereas values less than 0.7 suggest a ketogenic diet, fat gluconeogenesis, or ethanol oxidation. Respiratory quotient (RQ) is calculated as follows ... 

Respiratory quotient (qC02) Calculation from soil respiration divided microbial biomass carbon Indicates activity of microbial biomass determined in nonstandard laboratory with specialized equipment when high, considered an indication of stress on microbial biomass Rice et al. (1996)... 

Work by Voit and his associates continued so that by 1900 standard values for heats of combustion of different foods had emerged (Table 1). Respiratory quotients (RQ) were also derived, associated with the utilization of the different foods. The RQ is the molar ratio of the amount of carbon dioxide produced in the oxidation of a substance to the amount of oxygen needed for that oxidation. For carbohydrate the RQ is 1 ... 

Additionally, there is a growing use of off-gas analysis for measuring oxygen uptake, CO2 evolution and respiratory quotient measurement. 9, 641 However, this is not likely to find widespread use despite its usefulness unless the cost involved can be lowered. 

QUOTIENT FUNCTION QUOTIENT, RESPIRATORY QUOTIENT, SYNERGISM (Q, )... 

The respiratory quotient (RQ), which is the ratio of volume of O2 absorbed per hour to volume of CO2 released per hour, should ideally be 1 when the O2 supply is not limiting. It has been reported that the CO2 to O2 ratio value is approximately 0.8 during the early period of storage and 1.3 when sprout growth started (Burton, 1989 Gottschalk and Ezhekiel, 2006 Isherwood and Burton, 1975). 

Burton, W. G. (1963). The effect of stage of maturity and storage on the respiratory quotient of potato tubers. European Potato Journal, 6, 268-270. 

Isherwood, F. A., Burton, W. G. (1975). The elTect of senescence, handling, sprouting and chemical sprout suppression upon the respiratory quotient of stored potato tubers. Potato Research., 18, 98-104. 

The respiratory quotient (RQ) (of evolution of carbon dioxide to uptake of oxygen) has been found to be near 1.0 for plant tissues and for metabolized carbohydrates. Fats evolve less carbon dioxide and have an RQ... 

Amitrole had a drastic effect on the fixation of 14C02 by illuminated chloroplasts of Chlorella pyrenaidom, lowering the incorporation into sucrose by 95% at a concentration of 500 mg. per liter it did pot affect phosphorylated compounds.145 Carbohydrates hydrolyzable by acids were higher (51%) in treated, chlorotic corn leaves than in controls (32%), and this result was interpreted as due to increased metabolism of proteins and fats. The respiratory quotient of 0.8 to 0.88, compared to controls near 1.0, supported this interpretation.145... 

While unfavorable results have been reported for dairy consumption in other RCTs (Lanou and Barnard, 2008), Zemel et al. (2008) have reported that individuals consuming at least three servings of dairy products per day demonstrated a higher respiratory quotient (greater... 

Another possible mechanism to explain the potential effect of dairy products on weight loss derives from the observation that intakes of dietary calcium and dairy products have been associated with increases in energy expenditure and a lowered respiratory quotient. A lower respiratory... 

Chromium deficiency is characterized by glucose intolerance but also may include neuropathy, increased free fatty acid concentrations, and a low respiratory quotient. Chromium deficiency has been identified in the setting of long-term, chromium-free parenteral nutrition. 

Glucose intolerance, peripheral neuropathy, increased free fatty acid levels, low respiratory quotient... 

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