Respiration rate of bacteria as a function of oxygen concentration.
About: This article is published in Biochemical Journal.The article was published on 1954-05-01 and is currently open access. It has received 223 citations till now. The article focuses on the topics: Apparent oxygen utilisation & Acetobacter.
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TL;DR: This chapter discusses the mitochondrial respiratory control and the polarographic measurement of ADP : O ratios and the principle of the oxygen electrode has been summarized, and the design of the vibrating oxygen electrode for use with speetrophotometric studies is illustrated.
Abstract: Publisher Summary This chapter discusses the mitochondrial respiratory control and the polarographic measurement of ADP : O ratios. The polarographic oxygen electrode technique is used for measuring rapid changes in the rate of oxygen utilization by cellular and subcellular systems. Although the polarographic method measures changes in oxygen concentration of photosynthetic systems, yeast cells, and nerve, but the oxygen electrode technique is applied to a study the mitochondrial respiration and oxidative phosphorytation. The principle of the oxygen electrode has been summarized, and the design of the vibrating oxygen electrode for use with speetrophotometric studies is illustrated. The oxygen electrode apparatus can be calibrated in a number of ways. A more accurate calibration of oxygen content can be obtained by gas equilibration with various nitrogen-oxygen mixtures. When tightly coupled mitochondria are suspended in an isotonic buffer, a slow rate of oxygen uptake is measured in the presence of substrate and absence of ADP. Addition of ADP causes an immediate increase in the rate of oxygen utilization. The concentration of oxygen utilized is proportional to the amount of ADP phosphorylated to ATP. The type of oxygen electrode tracings is presented from which an ADP : O ratio (equivalent to a P : O ratio) can be directly calculated.
1,810Â citations
TL;DR: Results from studies of continuous cultures of Aerobacter aerogenes growing in chemically denned media indicate that specific growth rate (R) is a function of population density as well as the concentration of the limiting nutrient.
Abstract: SUMMARY: Results from studies of continuous cultures of Aerobacter aerogenes growing in chemically denned media indicate that specific growth rate (R) is a function of population density (P) as well as the concentration of the limiting nutrient (S). From these observations, and those of others, the following model for bacterial growth is derived: mic-21-1-40-si1.gif where um and B are growth parameters that are constants under defined conditions. This model is believed to have general applicability and to account for bacterial growth in both batch and continuous cultures.
590Â citations
TL;DR: The object of this review is to discuss briefly the central oxygen-dependent processes in mammalian brain and the short-term consequences of O(2) deprivation, but not the mechanisms of long-term adaptation to chronic hypoxia, placed on issues which have been the focus of recent attention and/or controversy.
560Â citations
TL;DR: This paper presented a kinetic model evaluating the supply of bioavailable Fe to surface seawater by ferrihydrite dissolution, photoreduction and siderophore-aided dissolution.
Abstract: Presented here is a combined historical account, current synthesis and a perspective of how the modern Fe cycle functions, and how this cycle has evolved through geologic time. We begin by highlighting how new developments in nanogeoscience demonstrate the importance of nanoparticulate Fe (oxyhydr) oxide aggregates in the modern iron cycle. We further document how these aggregates are supplied from shelf sediments, aeolian dust and icebergs to the global ocean. Based on these observations, we present a kinetic model evaluating the supply of bioavailable Fe to surface seawater by ferrihydrite dissolution, photoreduction and siderophore-aided dissolution. The model indicates that the rate of delivery of bioavailable Fe from icebergs to the Southern Ocean is at least as large as that by wind-blown dust. However estimates of all the main aqueous, nanoparticulate and colloidal (and potentially bioavailable) Fe inputs to the ocean are poorly-constrained.
We provide a historical perspective on the evolution of ideas as to how sedimentary pyrite formation is controlled and how these ideas led to the development of the Fe-based palaeoenvironmental proxies widely used today. This provides a springboard into our discussion of the ancient Fe cycle, which begins with a survey of how Fe interacts with a variety of other elements of biogeochemical interest including sulphur, oxygen and nitrogen. We highlight how interactions between these elements have evolved through geologic time, and how these interactions define the evolution of ocean and atmospheric chemistry. It is clear that the Fe cycle has gained a prominent role in regulating the biogeochemical function of the oceans through time. We offer, in the end, suggestions and a geochemical perspective as to how recent momentum in our understanding of the Fe cycle may be harnessed into catalysing future progress in the field.
558Â citations
372Â citations