Control by bacteria

The rapid oxidation of As(lll) has also been observed in the geothermally fed Hot Creek in California (Wilkie and Hering, 1998). Oxidation with a pseudo-first-order half-life of —0.3 h was found to be controlled by bacteria attached to macrophytes. Where microbial activity is high, there is frequently a lack of equilibrium between the various redox couples, including that of arsenic (Section 9.02.4.4). This is especially true of soils (Masscheleyn et al., 1991). 

The reaction rate is totally controlled by bacteria and, thus, is equal to the rate of bacterial eating chemical reaction (1), one mole of consumed nutriment contains 1/5 of CO2 and... 

Bacterial catabolism of oral food residue is probably responsible for a higher [NHj] in the oral cavity than in the rest of the respiratory tract.Ammonia, the by-product of oral bacterial protein catabolism and subsequent ureolysis, desorbs from the fluid lining the oral cavity to the airstream.. Saliva, gingival crevicular fluids, and dental plaque supply urea to oral bacteria and may themselves be sites of bacterial NH3 production, based on the presence of urease in each of these materials.Consequently, oral cavity fNTi3)4 is controlled by factors that influence bacterial protein catabolism and ureolysis. Such factors may include the pH of the surface lining fluid, bacterial nutrient sources (food residue on teeth or on buccal surfaces), saliva production, saliva pH, and the effects of oral surface temperature on bacterial metabolism and wall blood flow. The role of teeth, as structures that facilitate bacterial colonization and food entrapment, in augmenting [NH3J4 is unknown. 

It is now apparent that bacteria have developed resistance to heavy metals and the detoxifying process is initiated and controlled by metallo-regulatory proteins which are able selectively to recognize metal ions. MerR is a small DNA-binding protein which displays a remarkable sensitivity to Hg +. The metal apparently binds to S atoms of cysteine and this has been a major incentive to recent work on Hg-S chemistry. 

Overview. In the cultures of luminous bacteria, the bacterial cells are not luminous in their early stages of propagation. The formation of bioluminescence system is controlled by a substance called autoinducer that is produced by the cells of luminous bacteria. 

Bisulfite Adduct. A bisulfite addition complex of an aldehyde or dialdehyde has been proposed for use as an antimicrobial agent [1858,1859]. The complex is less toxic than free glutaraldehyde. In oil wells, its digestion by the sulfate-reducing bacteria releases the free dialdehyde that controls the bacteria. In these ways, a more economic and environmentally safer use of antimicrobial additives is likely. 

At least two enzymes compete for acetyl-CoA - the citrate synthase and 3-ke-tothiolase. The affinities of these enzymes differ for acetyl-CoA (Table l),and at low concentrations of it the citrate synthase reaction tends to dominate, provided that the concentration of 2/H/ is not inhibiting. The fine regulation of the citrate synthases of various poly(3HB) accumulating bacteria has been studied [ 14, 47, 48]. They appear to be controlled by cellular energy status indicators (ATP, NADH, NADPH) and/or intermediates of the TCA cycle. The 3-ketothio-lase has also been investigated [10-14,49, 50]. This enzyme is, above all, inhibited by CoASH [10,14,49]. This important feature will be further considered below. 

In purple bacteria investigated thus far, the development of the photosynthetic apparatus which is controlled by the oxygen partial pressure is not influenced by light. However, the prevalent light intensity modifies the morphogenetic process of formation of intracytoplasmic membranes. Light intensity also controls the total bacteriochlorophyll concentration per cell and per membrane protein, as well as regulating... 

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