Biohydrogen fermentative bacteria

Biohydrogen photo-bioreactors have been thoroughly analysed and revised for both microalgae (Posten, 2009) and photo-fermentative bacteria (Koku et al., 2003) cultivation. For a first rough classification, photo-fermentation can be lead out in batch or in continuous reactors, with the choice being determined by feed rate and type and biomass. 

Dark fermentation is the fermentative conversion of organic substrate to biohydrogen, it is a complex process manifested by a diverse group of bacteria by a series of biochemical reactions involving three steps similar to anaerobic conversion. Dark fermentation differs from photofermentation because it proceeds without the presence of light. 

The effect of pressure on biphasic fermentations has been reported for extremely thermophilic organisms (34), supercritical and compressed solvent extractions (35-37), biomethanation of synthesis gases (38), biohydrogenations (39), and bacteria for enhanced oil recovery (40). Fermentation in the presence of compressed and SCF CO2 has been conducted with a goal of using pressurized CO2 as an in situ extraction solvent. Extractive fermentation using compressed solvents could prevent toxicity due to the buildup of a fermentation product—in particular, ethanol—and greatly enhance the yield... 

Rumen fermentation is clearly involved in the development of MID, and many theories have been advanced to explain this metabolic syndrome. However, most have been found inadequate to explain the cause and mechanism of diet-induced MFD (15,123,124). A key development in understanding the mechanism of MFD was the recognition that it required two distinct conditions, (i) a shift in rumen fermentation and the population of rumen bacteria that was often characterized by a decline in rumen pH (121,125) and (ii) the presence of PUFA in the diet (126) that was associated with an alteration in rumen biohydrogenation resulting in an increase in milk fat content of trans 18 1 (121,123,126). Trans- is generally the major trans 18 1 isomer in milk fat, but Griinari et al. (126) demonstrated that the increase in the milk fat content of trans 18 1 with diet-induced MFD specifically involved an increase in the trans-lO 18 1 isomer. This was verified in subsequent investigations, and it was further shown that MFD was also associated with an increase in the milk fat content of trans-lO, cis-l2 Q.A (15,127-129). 

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