Chemosynthetic

Polyesters, such as microbially produced poly[(P)-3-hydroxybutyric acid] [poly(3HB)], other poly[(P)-hydroxyalkanoic acids] [poly(HA)] and related biosynthetic or chemosynthetic polyesters are a class of polymers that have potential applications as thermoplastic elastomers. In contrast to poly(ethylene) and similar polymers with saturated, non-functionalized carbon backbones, poly(HA) can be biodegraded to water, methane, and/or carbon dioxide. This review provides an overview of the microbiology, biochemistry and molecular biology of poly(HA) biodegradation. In particular, the properties of extracellular and intracellular poly(HA) hydrolyzing enzymes [poly(HA) depolymerases] are described. 

Weed competition for water and nutrients can have similar effects on fruit quality as described above for fertilisation. For example, if weed competition is completely prevented by chemosynthetic herbicides in conventional production, this can lead to excess supply of certain mineral nutrients, in particular nitrogen and potassium, which in turn results in reduced sensory quality and shelf-life (Section 16.2.2). On the other hand, excessive weed competition, in particular, during the pre-bloom phase and the end of the first shoot growth period (Gut and Weibel, 2005), can induce nutrient and/or water deficiency and a risk of quality loss. 

Owing to the prohibition of chemosynthetic pesticides under organic farming standards, there is a greatly reduced availability of intervention/treatment-based methods for disease and pest control in organic fruit production systems. The efficacy of the permitted biological control, extract or mineral element (e.g. S and Cu)-based crop protection products is also usually lower than of chemosynthetic pesticides. Permitted plant protection products show efficacies of between 60 and 80% while chemosynthetic fungicides and pesticides often have efficacy levels >95% (Tamm et al., 2004). 

F.J. Stewart, I.L.G. Newton, and C.M. Cavanaugh, Chemosynthetic endosymbioses adaptations to oxic-anoxic interfaces. TRENDS Microbiol. 13, 439-448 (2005). 

Gas Hydrate Mounds, Isolated Authigenic Carbonates, Small Fluid-Gas Expulsion Features Dense, Diverse Chemosynthetic Communities (Bacterial Mats, ... 

Very Localized and Poorly Developed Chemosynthetic Communities Highly Biodegraded Hydrocarbons... 

Geomar studied the habitat of hydrates and chemosynthetic communities for over two decades (see the review by Boetius and Suess, 2004). 

Near surface hydrates the chemosynthetic community and chemoherms... 

The stability of these solid-phase compounds is a function of pressure, temperature, and matrix salt composition (Sloan 1998 Marion et al. 2006). Gas hydrates could be important sources of high-energy carbon (Carney 1994). On Earth, gas hydrate deposits can sustain complex chemosynthetic communities (Sassen et al. 1999 Fisher et al. 2000). There is speculation that gas hydrates may be present on Mars and Europa (Kargel et al. 2000 Max and... 

Cano RJ, Borucki MK (1995) Revival and identification of bacterial spores in 25- to 40-million-year-old Dominican amber. Science 268 1060-1064 Carlson RW, Anderson MS, Johnson RE, Smythe WD, Hendrix AR, Barth CA, Soderblom LA, Hansen GB, McCord TB, Dalton JB, Clark RN, Shirley JH, Ocampo AC, Matson DL (1999a) Hydrogen peroxide on the surface of Europa. Science 283 2062-2064 Carlson RW, Johnson RE, Anderson MS (1999b) Sulfuric acid on Europa and the radiolytic sulfuric cycle. Science 26 97-99 Carney RS (1994) Consideration of the oasis analogy for chemosynthetic communities at Gulf of Mexico hydrocarbon vents. Geo-Marine Lett 14 149-159... 

Silverman, M.P. Lundrgen, D.G.,1959, Studies on Chemosynthetic Iron Bacterium Ferrobacillus ferrooxidans. J.Bacteriol. 78 326-331. 

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. 

Today, despite recent developments in combinatorial and other chemosynthetic strategies, flmgi and streptomycetes remain the most prolific sources of new candidate drugs and agrochemicals. Both phyla elaborate bicyclic, tricyclic and tetracyclic fused ring polyketides, however, a preliminary survey of isotopically labelled precursor incorporation studies has revealed a consistent difference in the modes of cyclisation by which their characteristic polybenzenoid metabolites are formed. These and subsequent observations (yide infra) provide the basis for a novel biosynthetic classification of microbial fused ring polyketides. 

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]... 

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