Thermococcus Species

Holden, J.F., Takai, K., Summit, M., Bolton, S., Zyskowski, J. and Baross, J.A. (2001) Diversity among three novel groups of hyperthermophilic deep-sea Thermococcus species from three sites in the northeastern Pacific Ocean. FEMS Microbiology Ecology, 36, 51—60. 

Since CD production without the application of solvents may lead to microbial contamination, the process should be conducted at increased reaction temperature. A heat-resistant cyclomaltodextrin glucanotransferase, stable at temperatures above 100 °C, was isolated from Thermococcus species. The enzyme possesses also a-amylase activity and the production of CD is possible without the addition of a-amylase for the preliminary starch liquefaction [48]. 

In the hyperthermophilic Archaea, NAD(P)-reactive enzymes are involved in recycling the reduced cofactors to produce H2 as a waste product as in the case of the NADPH oxidising hydrogenases from the hyperthermophilic Archaea, e.g. Pyrococcus species (Bryant and Adams 1989 Pedroni et al. 1995) and Thermococcus litoralis (Rakhely et al. 1999). These enzymes are also heterotetramers (Fig. 2.2C) with an apparently similar organisation of subunits and prosthetic groups to the Eubacterial examples of Group 5. 

A large number of hyperthermophilic Archaebacteria, especially the deep sea Thermococcale and Sulfolobus species elaborate a-amylases.79-82 Many have been cloned and sequenced.78 Pyrococcus furiosus,83,84 Thermococcus profundus,85 Thermococcus hydrothermalis,78 Sulfolobus solfataricus and Sulfolobus acidocaldar-iusS6 secrete thermophilic a-amylases. The a-amylases of all of these organisms have optimal enzyme activity at 90°C or higher and often only begin to show activity at 40°C or 50°C. Pyrococcus furiosus secretes an a-amylase with an optimum temperature of 100°C and a maximum temperature of 140°C.87 The optimum pH values vary between 5 and 9. Table 7.1 summarizes the names of the organisms, the optimum temperature, and optimum pH values for several of these enzymes. 

Despite the limited number of extreme thermophile species that have been examined for lipids, it appears that a few genera. Thermoplasma, Sulfolobus, Thermoproteus, Desulfurococcus, Thermococcus and Pyrococcus may be distinguished by their glycolipid and phosphoglycolipid compositions. However, it should be noted that genera in the Order Sulfolobales examined so far, such as Sulfolobus, Desulfurolobus and Metallosphaera have very similar lipid patterns, and it would be difficult to differentiate between them on the basis only of their lipids. 

Thermophile High temperature Moderate thermophiles (45-65°C) Thermophiles (65-85°C) Hyperthermophiles (>85°C) Amylases, xylanases Proteases, DNA polymerases Methanobacterium, Thermoplasma, Thermus, some Bacillus species, Aquifes, Archaec lobus, Hydrogenobacter, Methanothermus, Pyrococcus, Pyrodictium, Pyrolobus, Sulfolobus, Thermococcus, Thermoproteus, Thermotoga ... 

N-7 (from Themtococcus species 9°N-7). Sequence comparisons show that Pyrococcus and Thermococcus Family B DNA polymerases are highly related, exhibiting 75-90% identity. Comparisons presented here, and elsewhere, indicate that the Pyrococcus and Thermococcus Family B DNA polymerases exhibit similar yet distinct biochemical properties, which dictate their utility in particular laboratory applications. 

DIP was initially identified in Pyrococcus woesei and Methanococcus igneusP Later, this solute was detected in other hyperthermophilic archaea, namely in Pyrodictium occultum, and in Pyrococcus and Thermococcus spp. In several species of the Thermococcales large increases in the levels of DIP are observed at growth temperatures above the optimum, leading to the view that this solute has a thermoprotective role in these oiganisms. ... 

Although it is commonly accepted that EPSs do not appear to function as energy reserves, and microorganisms are unable to catabolize the EPSs produced, extreme thermophilic Sulfolobus, Thermococcus, and Thermotoga species produce EPSs that can act indirectly as extracellular storage polymers in their natural extreme environments where no other organic source has been identified. 

Although the membrane components containing pranyl chains are common to all Archaea, it is not the case for the sulfur derivatives of the sulfur-dependent thermophiles and hyperthermophiles that occur especially in, or in the vicinity of, underwater and terrestrial hydrothermal vents. Thus, in the species Thermococcus tadjuricus (strain Ob9) and Thermococcus acidaminovorans (strain Vc6bk), collected from deep-sea hydrothermal vents,a series of cyclic polysulfides was found that included lenthionine, which previously had been isolated from the terrestrial mushroom Lentinus edodes (Ritzau et al., 1993). Several of these compounds are presented in Figure 6.13. Similar polysulfides were isolated from red algae, such as Chondria califomica, and ascidians, such as certain Lissoclinum sp. (see Chapters 13 and 28). 

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