Bacteria chemosynthetic

Figure 12.7 Pathway of SC)42-reduction where FeS2 may serve as a starting material in thiol production, where S(0) and S(—II) (both found in FeS2) are used by chemosynthetic bacteria to form thiol (RSH) (e.g., glutathione) and SO42-. (Modified from Luther et al., 1986.)...

The property of chemotropicity testifies to the balance of the redox layer system with respect to the vertical fluxes of the oxidants and reductants supplied. This should be the well-defined sequence of changes with depth of the favorability of the potential redox reactions [ 17,75] that can be realized by the bacterial community. The development of bacteria in this case should affect the distributions of nutrients. By modern estimation [79] the chemosynthetic production is comparable with photosynthetic production, and that should in the same manner affect the consumption of inorganic nutrients and production of their organic forms. Besides this the possible abiotic chemical reactions and the sedimentation of particulate matter of different densities should also play their roles in this mechanism. 

Orla-Jensen. .. regarded the chemosynthetic bacteria as the most primitive group because they can live in the complete absence of organic matter and hence are independent of other living forms. This overlooks the fact that a chemosynthetic metabolism necessarily presupposes a rather highly specialized synthetic ability such as one would not expect to find in metabolically primitive forms. [37]... 

In addition to the pigmented bacteria, some colorless bacteria are able to fix carbon dioxide in the absence of light. These colorless bacteria, known as chemosynthetic or chemoautotrophic organisms, obtain energy for assimilating and reducing CO2 by oxidizing NH3, H2S, and H2. 

---