Bacteria, carbon dioxide assimilation

Bacillus typhosum, antigens, II, 166, 200 Bacillus vulgatus, Ievan formed by, II, 226 Bacteria, carbon dioxide assimilation by, III, 235... 

The photoreductive synthetic process that promotes the assimilation of carbon dioxide into carbohydrates, other reduced metabolites, as well as ATP (synthesis of the latter is termed photophosphorylation). Photosynthesis is the primary mechanism for transducing solar energy into biomass, and green plants utilize chlorophyll a to capture a broad spectrum of solar radiant energy reaching the Earth s surface. Photosynthetic bacteria typically produce NADPH, the reductive energy of which is converted to ATP. 

Carbon monoxide serves as the sole carbon and energy source for the carboxydo bacteria under aerobic conditions. Using water as the oxygen donor, carbon monoxide oxidase catalyzes the hydroxylation of carbon monoxide, giving carbon dioxide or bicarbonate for assimilation. Most work has been carried out on the enzyme from Pseudomonas carboxydovorans.,ftJ7>W38 The activity of carbon monoxide oxidase is considerably stimulated upon anaerobic treatment with sulfide and dithionite, or by aerobic treatment with selenite. The binding of selenite to the oxidase specifically activates the CO — methylene blue reaction.1039 The molybdenum cofactor liberated from selenium-activated carbon monoxide oxidase does not contain selenium. Here, then, the... 

Carbon dioxide is also fixed in the dark by photosynthetic organisms by the so-called Wood-Werkman reaction (Wood and Stjemholm, 1962). The CO2 assimilated, however, rarely exceeds that formed by dark respiration i.e. there is no net CO2 uptake. On the other hand, the amount of organic carbon derived from CO2 may be as high as 30% in heterotrophic bacteria and 90% in mixotrophic organisms. In the natural environment, non-photo-synthetic CO2 fixation by these organisms, together with the above-mentioned dark fixation by photosynthetic organisms, may under some condi-... 

Ammonia is also produced from burning of coal and bacterial decomposition of proteinaceous organic matter. Conversion of ammonia to ammonium salts will occur rapidly both in the atmosphere and in the soil but will result in less acidity of the soil. It is not known to what extent ammonia reduces excess greenhouse gases such as carbon dioxide in the atmosphere to form ammonium carbamate. Microbial assimilation of ammonium compounds consumes alkalinity of the soil as well as converting ammonium ions to nitrate. Nitrification is carried out by many aerobic bacteria. Nitrification is pH sensitive. Denitrification, which is an anaerobic process, is also pH sensitive. 

The discovery that certain bacteria could carry out photosynthesis opened up a new field of photosynthetic research. It was found that certain green-, red-, purple-, and brown-colored bacteria could produce organic matter from carbon dioxide upon illumination. The formation of organic matter was not accompanied by oxygen evolution. As a result of work with the green sulfur bacteria, van Niel (21) showed that their CO2 assimilation process was in close agreement with the following equation ... 

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. 

The methanotrophs have broadly been classified into two groups, type I and type II, on the basis of the carbon assimilation pathways in the metabolism of methane and on the arrangement of intracytoplasmic membranes. Two different metabolic strategies are utilized for the assimilation of carbon from formaldehyde formed in the course of the methane oxidation to carbon dioxide (Fig. 1). The type I bacteria involves the ribulose monophosphate pathway while the type II bacteria involves the glycine serine pathway. Recently, the Type I group has been further subdivided (type X), to accommodate strains... 

In 1935 Wood and Workman (407) demonstrated that typical heterotrophic bacteria (i.e., organisms which, like animal cells, depend on a supply of ready-made organic compounds for growth and activity) are able to assimilate carbon dioxide. The fixed carbon was found in the carboxyl groups of organic acids such as malic, fumaric, and succinic (408,409). Similar observations were made on protozoa... 

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