title: Physiological behaviour of Escherichia coli grown in opposing gradients of oxidant and reductant in the gradostat.
abstract: Gradients of nutrients are extremely common in nature, and this paper describes changes in the physiology of Escherichia coli grown in the gradostat, a series of five linked vessels with opposing gradients of glucose and of oxygen plus nitrate. Most growth occurred at the aerobic and anaerobic ends of the system. High rates of respiration, high energy charge and high activities of various oxidative enzymes were seen in the two most aerobic vessels; however, oxygen provision was presumably poor, because nitrate reductase activities were also high in this region. Vessels 3 and 4 showed the lowest values for respiration rate, enzyme activity and energy charge, and cells here were both nutrient starved and possibly inhibited by nitrite. Vessel 5 was highly anaerobic, resulting in the presence of hydrogenase activity. It was concluded that cells found in different regions of the gradostat had undergone biochemical differentiation in spatial gradients of electron donors and acceptors.
mesh_terms: D000227:Adenine Nucleotides / Q000032:analysis; D001431:Bacteriological Techniques; D002455:Cell Division; D003580:Cytochromes / Q000032:analysis; D004926:Escherichia coli / Q000502:physiology*; D005947:Glucose / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009994:Osmolar Concentration; D010101:Oxygen Consumption
chemical_list: D000227:Adenine Nucleotides; D003580:Cytochromes; D009566:Nitrates; D005947:Glucose