Aerobic photosynthetic bacteria

The Rhodospirillaceae and Chromatiaceae have the spirilloxanthin or the okenone pathway depending on the genus or species. All of the Ectothiorhodospiraceae have the spirilloxanthin pathway. The isorenieratene, the y-and -carotene, and the diapocarotene pathways are found specifically in the Chlorobiaceae, Chloroflexaceae, and Heliobacteriaceae, respectively. Aerobic photosynthetic bacteria mostly have the spirilloxanthin pathway, further most of these species have unusual carotenoids including non-photosynthetic carotenoids, such as carotenoid sulfates and carotenoic acids, which have no photosynthetic functions. 

Most of the aerobic photosynthetic bacteria so far desaibed have the spirilloxanthin pathway, further some also have unusual carotenoids as described below. 

Since aerobic photosynthetic bacteria contain many unusual carotenoids, it is difficult to list in this Table (See Table 9 and Fig. 13). These abbreviations are used in Tables 3-9. 

More than ten genera including about 30 species of aerobic photosynthetic bacteria have now been found (Table 9). They are distinguished from typical anaerobic photosynthetic bacteria in that they synthesize BChl only under the aerobic conditions and can not grow without even in the light. In some species, photosynthetic activities have been demonstrated. The low content of BChl, unique composition of carotenoids, and presence of non-... 

Recently, we reported that sulfidophilus grew and synthesized bacteriochlorophyll a (Bchl a) aerobically under both dark and light conditions in addition to the typical anaerobic light conditions (3). Furthermore, this bacterium is capable of photosynthesis under both anaerobic and aerobic light conditions which is different from the already known facultative anaerobic and aerobic photosynthetic bacteria. We have therefore concluded that R sulfidophilus is a link between the facultative anaerobic and aerobic photosynthetic bacteria. 

Two centers Rb pasteurianum) Aerobe photosynthetic bacteria Pseudomonas oleovorans 19... 

Free-living bacteria are, however, used as the source of the enzyme nitrogenase, responsible for N2 fixation (1,4,26,80), for research purposes because these ate easier to culture. The enzyme is virtually identical to that from the agriculturally important thizobia. These free-living N2-fixets can be simply classified into aerobes, anaerobes, facultative anaerobes, photosynthetic bacteria, and cyanobacteria. 

Fig. 2. An evolution diagram illustrating a suggestion of common ancestry of some present-day organisms. The essential features of present-day photosynthesis may have originated in the prebiotic era and is preserved in its most primitive form in (at least some) present-day phototrophs. The heterotrophs may have developed parallel with the aerobic nonphotosynthetic bacteria, some l to 1.5 x 109 years after the emergence of the cyanobacteria. The eukaryotic photosynthetic organisms developed much later, perhaps some 1.5 to 0.5 x 109 years ago. The archaebacteria are primitive organisms that seem to have no evolutionary relation with the present prokaryotes.21 Little is known about their energy metabolism. Tentatively, they are considered as a very early form of cellular life.

Fixation The process of N fixation is carried out by an incredible diversity of organisms, including heterocystous and nonheterocystous cyanobacteria, aerobic, facultative anaerobic and anaerobic eubacteria, and by photosynthetic bacteria... 

The most likely setting of symbiosis is a microbial mat community, in which a complex community of cells is clustered across a redox boundary, cycling and recycling redox power (Nisbet and Fowler, 1999 Nisbet, 2002). The aerobic top of the mat would include photosynthetic cyanobacteria, above photosynthesizing purple bacteria. There would be a very sharply focused redox boundary. Below would be the green photosynthetic bacteria, and at the base the methanogens and the hydrogen producers. 

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