Bacteria organic phosphorus

In models in which bacteria are not modelled explicitly, nitrification is modelled as oxidation of ammonium without explicit description of growth of the chemolitho-trophic bacteria that perform the oxidation. This process is shown in Table 16.15. Other oxidation processes undertaken by chemo-lithotrophic bacteria are modelled similarly. When omitting the growth of chemolitho-trophic bacteria, organic phosphorus is not affected by these processes. 

The organics contaminants, whose concentration is usually expressed in terms of biochemical oxygen demand (BOD), are utilized as food for the bacteria. Besides oxygen, nutrients (nitrogen and phosphorus) are also needed by the bacteria for its metabolism. The concentrations of oxygen, bacteria, organic contaminants, and nutrients, as well as other factors, have an affect on the biological treatment rate. 

The maxima of organic phosphorus and urea content typically observed in summer at the onset of hydrogen sulfide vicinity were absent in the winter. The concentrations of organic nitrogen were lower in winter than in summer. These observations may be related to the decrease in the number of bacteria and a reduction of the rates described by Sorokin [23]. 

Utilization of phosphate monoesters by microalgae and bacteria is effected by phosphomonoesterases (phosphatases) of broad specificity present at the cell surface. Hydrolytic release of PO4- from sugar phosphates, nucleotide phosphates, phospholipids, and phenyl phosphates, to name a few, enables a wide variety of phosphorus containing compounds to be utilized as phosphorus sources for growth of microbes. Ultrastructural observations and results from biochemical experiments indicate that extracellular phosphatases cleave the phosphate moiety from dissolved organic phosphorus compounds, which is then internalized, leaving the carbon skeleton outside the cell (Kuenzler and Perras, 1965 Doonan and Jensen, 1977). 

Less than 3% of soil organic phosphorus is present as nucleic acids and derivatives derived from the decomposition of living organisms (Dalai, 1977). The four bases of DNA have been identified in humic acids (Anderson, 1961). The presence of nucleic acids and derivatives in the soil was confirmed by the isolation of two pyrimidine nucleoside diphosphates (Anderson, 1970). Nucleic acids are rapidly mineralized, re-synthesized and combined with other soil constituents, or incorporated into microbial biomass (Anderson and Malcolm, 1974). Nevertheless, the interaction of nucleases with soil constituents can inhibit DNA hydrolysis, with important environmental consequences related to extracellular gene uptake by bacteria (Demanfeche et al., 2001). 

Heterotrophic bacteria are now seen as potentially important links between dissolved resources and higher trophic levels (Vadstein et ah, 1993). This altered view of the role of bacteria has especially important consequences for conceptualizing the significance of bacteria in phosphorus dynamics at the base of the food web, because heterotrophic bacteria differ from phytoplankton in being relatively phosphorus-rich organisms (Vadstein, 2000). Heterotrophic bacterial metabolism of phosphorus is dependent not only on phosphorus availability but also on the availability of labile dissolved organic carbon in the immediate environment. 

Although aquatic biochemical ecologists have focused nearly exclusively on lytic processes for dissolved organic phosphorus utilization, heterotrophic bacteria can directly take up certain organic phosphorus compounds from their surrounding environment without prior hydrolysis (Table 9.2). E. coli is known to have two different processes by which glycerol 3-phosphate can be taken up without prior hydrolysis... 

Could bacteria act to attenuate or modulate informational signals through their capability to interact with dissolved organic phosphorus Recent studies suggest the likelihood of such a possibility. When added to seawater, cyclic adenosine monophosphate can enhance the cultivation success of bac-terioplankton in marine (Bruns et al., 2002) and freshwater (Bruns et al., 2003)... 

Siuda, W. and Chrost, R.J. (2001) Utilization of selected dissolved organic phosphorus compounds by bacteria in lake water under nonlimiting orthophosphate conditions. Polish Journal of Environmental Studies 1 0, 475 83. 

Soil organic phosphorus includes phosphorus in living soil organisms and dead organic matter. Soil bacteria and fungi constitute the bulk of phosphorus in soil organisms, while their turnover is decided by... 

Soil organic phosphorus composition does not reflect organic phosphorus inputs to soil, which are dominated by phosphate diesters derived from plant and microbial remains. For example, nucleic acids constitute around 60% of the intracellular phosphorus in fungi and bacteria (Webley and Jones, 1971), while phospholipids are the major form of organic phosphorus in fresh plant tissue (Bieleski, 1973). In contrast, inositol phosphates constitute only a small proportion of total organic phosphorus inputs, yet are the... 

Growth of chemolithotrophic bacteria, such as nitrifiers, sulphide-oxidizers and methane-oxidizers, is an alternative means of primary production for the conversion of phosphate to particulate organic phosphorus. These bacteria may act as scavengers for phosphorus transported from the deep water... 

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