Colonisation process

Semi-natural areas are extremely valuable habitats in the agricultural landscape with respect to the conservation of threatened species. They are also of great functional importance for nutrient cycling (e.g. meadows retaining nutrients and thereby preventing leaching) and processes of succession (e.g. colonisation) (Tybirk et al. 2004). 

Other geographical problems with the abiotic hypothesis (Dorn, 1998, p. 242-243) include rapid pH fluctuations in the range to mobilise and oxidise Mn where varnish does not commonly occur (in such as places as the rainshadows of Mauna Loa and Mauna Kea on Hawai i) purely inorganic Mn fixation experiments yielding too low concentrations of Mn millimetre-scale distribution of varnish mimicking the pattern of microbial colonisation an inability to explain botryoidal varnish textures by abiotic processes and an inability to produce true varnish experimentally without microorganisms. 

The question of microbial sulphide weathering at vents is currently being seriously addressed by a variety of combined approaches, including textural and isotopic biomarkers, water-rock interaction experiments and in situ colonisation experiments (Edwards McCollom, 2001 Leveille Juniper, 2002 Leveille etal., 2002). Sulphide weathering may prove to be a quantitatively important, long-term biogeochemical process at mid-ocean ridges. 

The above examples were chosen to illustrate the diversity in microbial mode of niche colonisation. To stress the multifactorial and dynamic nature of colonisation and infection processes, the example of N. meningitidis is illustrated below. 

Fig. 4 Possible stages in the colonisation and pathogenic processes of N. meningitidis. A model based on epidemiological and in vitro experimental observations. Phase variation of surface structures is common in N. meningitidis and capsule-deficient phenotypes are found in the nasopharynx. Such a phenotype is invasive but is serum sensitive and does not survive in the blood. In the case illustrated on the right, where infiltration of capsule-expressing bacteria is possible, dissemination throughout the body may ensue unless the host has the ability to clear this phenotype efficiently from the blood (NP Nasopharynx EC epithelial cell ECM extracellular matrix)...

Deterioration processes, especially caused by soluble salts interacting with moisture and microbial colonisation, will be presented in this chapter, in relation to restoration/consolidation treatments and their effects. Damage will also be considered that has occurred as a later consequence of extended ingress of moisture through damaged parts of the building or the use of unsuitable building materials. 

There is a well defined sequence of events in the development of marine fouling on surfaces recently introduced to the aqueous environment. Initially bacteria attach to the surface forming a slime layer, very much as described in Section 12.2.2. The colonisation of the surface by the bacteria may be regarded as a conditioning process, making it more suitable for the settlement of barnacles and mussels. 

For the initial stages of biofouling when the growth on the surface is negligible the colonising development of the biofilm is directly related to the mass transfer of the cells and the macromolecules. Assuming that these two processes are occurring simultaneously, it is possible to write an equation that describes the total transport ( ror-o) surface as... 

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