Glycerol accumulation

Fish from temperate zones have been most studied, and from these we learn that temperature may influence the character of metabolic rhythm both indirectly, through food supply, and directly, through the limited temperature ranges within which one or other vital activity can or cannot occur. It is the response or the preference that fish show to temperature that shapes the rhythmic pattern. This is well shown in two diametrically opposite fish from the Black Sea, the warm-water anchovy and the cold-water sprat (Figure 34). The curves that describe the course of triacyl-glycerol accumulation in these species mirror each other, as the fish oppose one another in their time of spawning. 

One of the toxic effects of acetaldehyde is inhibition of tubuhn polymerization. Tubulin is used in the liver for secretion of very low-density lipoprotein (VLDL) particles containing newly synthesized triacylglycerols. As a result, these triacyl-glycerols accumulate in the liver, and he has begun to develop a fatty liver. Acetaldehyde may also damage protein components of the inner mitochondrial membrane and affect its ability to pump protons to the cytosol. 

Gene expression, adaptation to high osmolarity and glycerol accumulation... 

Regulation Between Alcoholic Fermentation and Glyceropyruvic Fermentation Glycerol Accumulation... 

The free fatty acids formed by lipolysis can be reconverted in the tissue to acyl-CoA by acyl-CoA synthetase and reesterified with glycerol 3-phosphate to form triacylglycerol. Thus, there is a continuous cycle of lipolysis and reesterification within the tissue. However, when the rate of reesterification is not sufficient to match the rate of lipolysis, free fatty acids accumulate and diffuse into the plasma, where they bind to albumin and raise the concentration of plasma free fatty acids. 

As discussed in this book (Chapter 2, for example) a main difference between fossil fuels and biomass as feedstocks is that in the former case the functionalization of base chemicals obtained from the oil (ethylene, propylene, aromatics, etc.) occurs essentially by introduction of heteroatoms, while in the case of biomass-derived based chemicals (glycerol, for example) it is necessary to eliminate heteroatoms (oxygen, in particular). Consequently, the catalysts required to develop a petrochemistry based on bio-derived raw materials need to be discovered and cannot simply be translated from existing ones, even if the knowledge accumulated over many years will make this discovery process much faster than that involved in developing the petrochemical catalytic routes. 

Zhu, M. M. Lawman, P. D. Cameron, D. C. Improving 1,3-propanediol production from glycerol in a metabolically engineered E.coli by reducing accumulation of glycerol-3-phosphate, Biotechnol. Prog., 2002, 18, 694-699. 

Accumulation of cytoplasmic NADH and glycerol 3-P may also contribute to lipid accumulation in alcoholic liver disease. Free fatty acids released from adipose in part enter the liver where P-oxidation is very slow (high NADH). In the presence of high glycerol-3P, fatty acids are inappropriately stored in the liver as triglyceride. 

Product inhibition in the glycerol fermentation has been studied in several investigations [12, 38,43-45]. The strongest inhibitor seems to be 3-hydroxy-propionaldehyde. This compound is normally an intracellular intermediate that does not accumulate. However, under conditions of high glycerol excess, it may be excreted into the medium. Whereas K. pneumoniae is able to reduce the accumulated 3-hydroxypropanal further to 1,3-PD, Enterobacter agglomerans is killed by the aldehyde as soon as a concentration of 2.2 g/1 has been reached [44], C. butyricum excretes only very small amounts of 3-hydroxypropanal [46]. 

---