Bacteria-Specific Models

There have been many attempts to explain MIC in terms of models. We will look at just some of them, reminding the readers that more can be found in the references of the works that are quoted here. The models about MIC can be grouped into two categories those that try to explain MIC in terms of involvement of a certain species of bacteria, mainly SRB (bacteria-specific models), and those that try to encompass the MIC phenomenon as a whole and explain—as well as predict—it (process-specific models). 

These two kinds of MIC models have to apply some assumptions (as is true for all models and, in fact, modeling procedure) to be able to use their mathematic-chemical mold for capturing and shaping the facts observed on the field. 

---

Although this model has not been classified as bacteria specific, it is seen that the only bacterial species of concern in this model is still SRB. 

What can be said, as a whole, is that all of these models, either bacteria specific (mechanistic) or process specific, are useful tools helping us in assessing the risk of MIC. It is true that they just look at MIC as induced by bacteria (certain groups of CRB) and therefore overlook possible contributions from macroorganisms. All of these models are useful for one type of material and not... 

The present model is based on mass balances for three main components representing phytoplankton (A), nutrients (E), and organic phosphorus (C), which can describe phosphorus cycle within a water body as follows. Phytoplankton biomass is produced by the photosynthesis reaction, consuming nutrients (in lakes and reservoirs, the limiting nutrient is phosphorus) and dissolved carbon dioxide, with solar radiation and adequate temperature. Upon death, phytoplankton biomass increases the pool of organic phosphorus, which is in turn converted to phosphate by mineralization bacteria. The model has several kinetic parameters that have to be estimated based on collected data from the specific reservoir under study. 

Molecular simulation methods can be a complement to surface complexation modeling on metal-bacteria adsorption reactions, which provides a more detailed and atomistic information of how metal cations interact with specific functional groups within bacterial cell wall. Johnson et al., (2006) applied molecular dynamics (MD) simulations to analyze equilibrium structures, coordination bond distances of metal-ligand complexes. 

Compared to the sizes of living cells,1 IUV and LUV resemble the dimensions of enveloped viruses (ranging from 80 to 400 nm) [94], while GUVs resemble typical bacteria and erythrocytes (1-7 pm). Eukaryotic cells tend to be even larger (10-30 pm in animals, 10-100 pm in plants). These dimensions imply that, except for viruses or specific sub-cellular membranes, flat bilayers are the only relevant membrane models. Hence, macroscopically oriented bilayers on solid supports (see... 

ABC transporters involved in the uptake of siderophores, haem, and vitamin B]2 are widely conserved in bacteria and Archaea (see Figure 10). Very few species lack representatives of the siderophore family transporters. These species are mainly intracellular parasites whose metabolism is closely coupled to the metabolism of their hosts (e.g. mycoplasma), or bacteria with no need for iron (e.g. lactobacilli). In many cases, several systems of this transporter family can be detected in a single species, thus allowing the use of structurally different chelators. Most systems were exclusively identified by sequence data analysis, some were biochemically characterised, and their substrate specificity was determined. However, only very few systems have been studied in detail. At present, the best-characterised ABC transporters of this type are the fhuBCD and the btuCDF systems of E. coli, which might serve as model systems of the siderophore family. Therefore, in the following sections, this report will mainly focus on the components that mediate ferric hydroxamate uptake (fhu) and vitamin B12 uptake (htu). 

Parajuli, P. B., Mankin, K. R., and Barnes, P. L. (2009). Source specific fecal bacteria modeling using soil and water assessment tool model. Bioresour. Technol. 100, 953-963. 

For keyhole limpet hemocyanine (KLH) both antibody responses and delayed type hypersensitivity (DTH) reactions can be determined [43—45]. In addition several infectious models, including bacterial, viral and parasitic infections may be used to challenge the immune system [18,46]. As survival and eradication of the infections is the primary function of the immune system, these models provide direct information on the functional status of the immune system. Direct immunotoxic compounds will induce immunosuppression and thus an increase in infection rate and/or severity of the infection. The number of infectious agents (bacteria, parasites, or viral colonyforming units), increased morbidity and mortality are indications for an immunotoxic effect. Also a reduction in specific antibody levels in animals treated with the test compound compared to nontreated controls indicates immunosuppression. 

---