Energy available to thermophiles

Subsea hydrothermal vents, as mentioned in the previous section, are sites of intense biological activity, relative to the rest of the ocean floor (e.g., Van Dover, 2000 Zierenberg et al., 2000). Life here ranges in complexity from single cells to higher forms such as tubeworms. The vent ecosystems are unique in many ways, including the fact that the primary producers create biomass not by photosynthesis, as is familiar in more accessible environments, but by chemosynthesis. 

As fluid from the hydrothermal vent mixes with seawater, chemolithotrophic microbes by this process harvest energy from the chemical disequilibrium among redox reactions, forming the base of the ecosystem s food chain. Microbes can 

We begin in REACT by defining the composition of local seawater. The procedure is as before 

In a similar fashion, we constrain the composition of fluid from the hydrothermal vent 

T initial 273, reactants = 4 dx init = 10 -4 step increase = 2 dxplot = 0 

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The subject of energy transfer in phycobilisomes and their sub-structures already has a large literature (see Ref. 65 for a review), mostly beyond the scope of this chapter. However, two of these sub-structures - trimeric C-phycocyanin from the thermophilic cyanobacterium Mastigocladus laminosus and hexameric C-phycocyanin from the cyanobacterium Agmenellum quadruplicatum-have very recently become respectively the third and fourth photosynthetic pigment-protein complexes for which structural models based on single-crystal X-ray diffraction near atomic resolution are now available (Refs. 66,67 and Chapter 11). Since these are presently the only such complexes, in addition to the two already discussed (Sections 5 and 6), it seems appropriate to conclude this review of exciton effects with some brief remarks on these C-phycocyanin structures. 

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