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Oxygen Transfer in Cell Culture Bioreactors
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
Most oxygen taken up by cells is used to oxidize carbon sources. The most important carbon sources for mammalian cells in culture are glucose and glutamine. The oxidation reaction of both compounds yields carbon dioxide at a stoichiometric ratio (CO2:O2) of 1.0 and 1.1, respectively. The mole ratio of CO2 produced to that of O2 consumed is called the respiratory quotient (RQ). Since the carbon source consumed in the largest quantity by cells is glucose and the next is glutamine at about 1/5 of that of glucose, the RQ of cells in culture is very close to 1.0 (Panel 11.11). The CO2 produced by cells needs to be removed from the culture to avoid excessive accumulation, which would cause a drop in pH or an inhibition of growth. A key role of aeration in cell culture is thus the removal of carbon dioxide, in addition to the supplying of oxygen. The removal of carbon dioxide generated by cell metabolism requires the presence of a gas phase just like the supply of oxygen, except that the transfer through the gas–liquid interface is in the opposite direction (Panel 11.12).
Biotechnological Potential of Hydrogen-Oxidizing Bacteria
Published in Debarshi Kar Mahapatra, Swati Gokul Talele, Tatiana G. Volova, A. K. Haghi, Biologically Active Natural Products, 2020
Tatiana Grigorievna Volova, Evgeniy Gennadievich Kiselev, Ekaterina Igorevna Shishatskaya
The most important function of the regeneration component in the life support system is utilization of carbon dioxide expired by humans. Human respiration intensity is characterized by the respiratory quotient (RQ)-[CO2/O2]. Idealized gas exchange in humans can be represented as follows: CH2O+ O2→CO2+ H2O
Basic Concepts
Published in Epstein Eliot, The Science of Composting, 2017
The term “respiratory quotient” (RQ) is the ratio of COz/O2 consumed. If one molecule of CO2 is produced for every O2 molecule consumed, RQ equals 1.0. Gray et al. (1973) indicated that different organic compounds have different RQ values. For example, during the oxidation to CO2 and H2O, starch has an RQ of 1.0, proteins have an RQ of 0.81, and fats have an RQ of approximately 0.71. According to Wiley and Pierce (1955) and Schultz (1960), RQ for composting was in the range of 0.87 to 0.91. This shows that less CO2 is produced in relation to oxygen. However, chemical reactions releasing O2 also result in a lower RQ.
Biological drying of municipal solid waste from landfill
Published in Drying Technology, 2020
Radosław Slezak, Liliana Krzystek, Stanisław Ledakowicz
Respiratory quotient (RQ) determines the production of CO2 (in moles) in relation to the amount of assimilated O2 (in moles) being an indicator determining the stabilization of the tested material. Table 1 shows the average RQ during the biodrying of waste at 23 and 50 °C. Similar results of reducing RQ from 1.0 to 0.87 molCO2/molO2 were obtained by Gea et al.[38] and Komilis and Tziouvaras[39] during aeration of organic matter.